A week in the shop

This last week was not the most productive week in the shop, as I spent quite a bit of time doing software contract work, which is how I pay the bills currently. I did get into the shop for a little bit, so here's a look back at the week.

First up I tried to plug the hole in the neck that the CNC router damaged a while back. Unlike with the body the hole in the neck isn’t a regular 2D shape, it was a irregular gouge taken from the side when the router bit snapped as the CNC router erroneously drove it into the bed. After clearing it up a little with sand paper and a small file, it looked like only a small amount of the damaged area would be visible once the neck was carved. If you look at the picture below then it’s only the top 2 or 3 mm that’ll remain post neck carve.


Given the small area that needs patching I thought perhaps I’d try plug it with a mix of sawdust and wood glue. Initially this looked promising:


But once it dried it looked a lot less good:


I suspect I’ll live with this for this neck, given there’s other areas of pain I need to deal with and the idea is just to make *something* out of these damaged parts rather than make them perfect, but I must confess that after the success with body patching from a couple of weeks ago I'm a little sad that this didn't work out as well, but that's all part of learning. Clearly whilst you can use the sawdust and wood glue trick successfully with dark woods (as I’ve done successfully on wenge) lighter woods it doesn’t work so well on.

My nemesis, also known as Makespace’s CNC Router, also continued to plague me this week. Whilst I don’t trust this machine, it still works will for many people’s purposes and Makespace, and as Makespace is a community workshop and I know more than average about the machine, I’ve become a recognised owner of the machine, and as such I do occasional maintenance on it. 

This week we needed to replace the sacrificial bed on the machine; this is the bit of MDF that is anchored to the bed of the machine that people then mount their workpieces to. Having a soft bed like this rather than a metal bed makes using it a lot easier in general (you can just screw your material to the bed rather than fight with lots of annoying clamps), but as the name implies, the sacrificial bed needs replacing from time to time. 

Replacing it is fine, but when you do so you also need to level it. The general approach to this is to use a wide router bit (e.g., I have a 1” wide router bit I use for facing off material). But I’d noticed a while ago that doing this was leaving ridges in the material, implying the machine spindle wasn’t truly perpendicular to the machine bed. You can see the effect in this picture I took a couple of weeks ago in the face of this body I was patching - those ridges are because the 1” router bit wasn’t truly flat, but at a slight angle.


Before I levelled a new sacrificial bed I wanted to see if I could sort out this problem, as there’s no point trying to level something just to have it not actually flat. The way to assess whether the spindle on the router is true or not us by a process called tramming, where you take a “tram”, which is just a bit of metal that fits in the spindle, goes out about 20 cm to the side, and then down a bit. The idea is that if everything is good, then you can fit the tram to the CNC Router, get the tip to touch the bed at one point, and then spin it 180˚, and it should still be touching. If there’s a gap or you can’t turn it due to the tram hitting the bed then you have a non true spindle. You can see the setup here.


In the picture I’m using a bit of metal over the foam bed cover to make it easier to tell whether I’m hitting or not (whether I get a nice clink or not). Sure enough, when measured I discovered that the spindle was out by about 1.5˚, which is quite a bit for a machine like this.

Now that I knew it was definitely misaligned, the next question is what to do about it. Helped by other, more experienced, Makespace members, we spent an afternoon working back to find the source of the misalignment, which was that the top arm was slightly off, rather than the spindle itself being off. This we found using a Dial Test Instrument (DTI), which is an extremely sensitive gauge that measures small changes in distance as it’s run along a surface.


Using this we measured all the degrees of freedom and was pleased to find the misalignment was just limited to the one axis. Having found the source of the mis-alignment, and knowing how much it was misaligned by, we then shimmed the mounts for the main arm by an appropriate amount, which involved a bit of disassembly and re-assembly of the machine.


Afterwards we were left with a wonderfully aligned spindle, and at some point this week I can find a little time to make the new sacrificial bed for the router.

Overall I’m still feeling frustrated I’m not making progress with more guitars: whilst I have managed to finish the prototype offset, of which I'm very proud as my best guitar to date, I've not made nearly as much progress, or as many guitars, as I'd hoped. I’m stuck in a kind of limbo right now whereby although I can move things forward by hand, there’s certain jobs where I know it’ll be better done by a working CNC router, and the Makespace CNC router works almost well enough that I end up procrastinating trying to see if I can find ways to move things forward from that perspective. I'd hoped my trip to DoES in Liverpool would provide a more readily available path to completion, but whilst I'd still like to do something with DoES that's not a short term win in the way I'd hoped. 

None of which pontificating and procrastination gets guitars built of course. I need to push more into making myself happy that I have a route to completion on the guitars to a quality level I'm happy with over the next few weeks. I think this is where I'm getting stuck: I have a high quality bar for what I think I can ship as a guitar, and I'm not experimenting enough to try and close that gap based on what I think I can achieve with the tools available to me.

I do also need to start moving on the guitars I have made to cover some of my costs. The prototype offset will go on sale shortly after it completes final setup at full price (£1800), so if that model appeals to your, get in touch, otherwise I imagine it’ll appear on reverb in the next month. I’m also going to sell my P90 based blues deluxe model at some point; my plan is to make it a new neck first as it’s not up to the standard I’d want if charging full price, but given lots of people who have played it have loved it I’m also happy to let it go as is for a discount (50% off, aka £900), so if that guitar feels like your thing then get in touch if you fancy a bargain before I rebuild the neck.

A week in the shop

My week notes are a bit late due to a weekend spent learning how to to hunt, gather, and cook (and make fire) in a forest in Kent and doing contract software work from when I got back, but here’s a belated catchup on the fun in the shop last week! I love this image, which pretty much covers the things I've been working on in the shop during that week:


Let’s start with some non-guitar design and woodwork fun. The week before last I talked about how my friend Jason was visiting, and together we were working on making a case for his nice nixie clock that he’s been building. 


As a quick recap from that week: we’d gone through several iterations of the classic rapid prototyping flow: we had a design in Fusion 360 of the clock and the case, which we’d then 3D print using one of Makespace’s Ultimakers, which we’d test fit/measure, work out what needed changed, updated our design, print again, etc. After a few times around, we’d got to the point where we we were happy with the design and we had 3D printed case we were happy with.


We also used the laser cutter to cut a nice acrylic base for the case. Although the case looks simple (it's just a box with some holes, right?), there’s two points of complexity in the design. Firstly, the v1 clock circuit board wasn’t really designed with the idea it’d be mounted in a case, and the layout is a little awkward for this purpose: the headers supporting some of the child boards (e.g., the left most one in the first picture) are very close to the holes where we'll need to mount the board to the case. This, coupled with the USB port that powers the clock being almost flush with the rear of the board, means the mount posts in the box have to be very narrow and have thin walls around the screw holes, as shown here:

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The posts look big in that picture, but are only 5 mm across and have to take a 2 mm screw, so we really don’t have much margin for error here before things won’t fit. Indeed, we’re sufficiently close that we have had to route the channel you can see above on the inside of the rear wall to let us slide the almost but not quite flush USB port into the box. The other complexity comes from the fact that the ventilation and USB port are on the rear wall, not on the top or bottom. Why is that an issue? Well, we'll be milling the final box on the CNC router, which only works in one plane, so whilst we can hollow out the box, cut the nixie holes and the screw holes in the mount posts, we can't use that same process to make the holes on the back, we’ll need to do those separately afterwards. Given the rear wall is only 2 mm thick (going down to 1.2 mm where the USB port channel is) we’ll need to be very careful when we eventually drill those holes in, as we risk splitting the material given how thin it is.

Once happy with the 3D printed designs, it was time to start thinking about making it out of wood. Jason ordered some wonderful wild olive wood from Exotic Hardwoods UK Ltd, which is possibly the nicest bit of wood I’ve ever worked with. It looks beautiful, and whilst we were working on it it made the workshop smell very nice. 


The wild olive wood is as expensive as it is beautiful, and thus following our regular mantra of “measure, measure, cut”, before putting our expensive nice wood into the CNC router we first glued together a few layers of MDF I had laying around to about the correct thickness, and tested cutting out the clock case on this. People have a tendency to assume CNC routing is the easy way out: you just feed your design into a machine and press go, but it’s actually quite a labour intensive process the first time you cut a design. The CNC router is a dumb machine that will only do what you tell it; you have to use Fusion 360 to work out all the tool paths you want it to follow, use experience or trial to work out which cuts will work best in a given scenario etc. The first time I machine anything on the CNC router, although I work out all the tool paths before I enter the shop, I’m always revising the tool paths as I go as I realise assumptions I’d made about how best to approach things were wrong, or I can see a better way to get the machine to craft what I want.

As such it took Jason and I the better part of a morning to get the first MDF version milled out:


We learned a lot in this process about how to approach the milling of the wood, and we then could test fit against the actual board to check nothing had been lost in translation. We also at this point tested our plan to make the holes on the back using a laser cut template which we clamped to the back and used the pillar drill to make the actual holes. This mostly worked fine, but we learned that we needed to put a block of wood into the box whilst we drilled to stop the wood splitting given it was so thin.


Happy with our design, we then set about taking the wild olive wood and repeating the process. Even here we ended up having to tweak the design and react as we went along: we quickly realised that the harder olive wood reacted differently to being cut compared to the MDF, having a tendency to chip at the edges if we took too much off, meaning we had to go much slower with the olive wood than we had with the MDF.

Thus a few hours of tending the CNC router and on my side a lot of nerves given I know it's not been reliable on my more complex guitar designs, we had successfully made the shape of what we hoped would be the final version of the case!


Given it was now late evening and we’d been in the workshop all day, we decided to defer cutting the rear holes until later in the week - there's no point rushing on a job like this given the cost of a mistake will put you back to square one. Still, even if we couldn't yet power the board on, it was nice to see another physical manifestation of the “measure, measure, cut” mantra by comparing the 3D printed version, the MDF version and the final olive wood version of the case:


Working with an organic material like wood is full of surprises, and when two days later we came back to our case to drill the rear holes we were initially quite confused: the acrylic template we’d made for drilling the holes (and had used on the MDF version successfully) didn’t match the size of the case we’d made! More weirdly it did still match the size of the other cases, just not the final wild olive one. What was going on? We broke out the callipers, and discovered the rear of the case, which should have been 33 mm tall, was 1.2 mm shorter than expected!

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(as an aside, just check out the lovely flame texture in that olive wood :)

At first we assumed perhaps we’d messed up on the CNC router, but going back to our CAM design we could see everything was good there. Only then did we check on the properties of olive wood in a wood database: it turns out wild olive wood can shrink by up to 15% in volume once cut out! The nice block of wood we’d started with was sealed in wax to prevent it shrinking, but now that we’d cut this bit of the wood free and hollowed it to a series of thin walls it’d quickly started to shrink. Luckily the board still fitted and our screw holes were still just about aligned with the board, but we decided that it was probably best that we quickly get the holes on the rear wall drilled and get to oiling the wood as soon as possible to see if we could limit further shrinkage.

As mentioned earlier, given how thin the rear wall is, to prevent the wood splitting when we drilled the rear holes we found some scrap wood and quickly machined it (a fancy way of saying I measured it, roughed it on the band saw, and then sanded it) to the right size to make a snug fit.


We then taped on our template, noting that despite the shrinkage the internal mount posts in the case hand’t shrunk notably, so we could keep the top edge of the template flush with the top of the box and still have the USB port hole align with the mounted board. 


For the USB port hole, which is small slot rather than a single circular hole, we actually just drilled two holes, one at either end of the slot, and then Jason hand filed the wood in between to make the correct gap.


After which we were able to finally do our first assembly of the box, and it looked just as lovely as we’d hoped:


Now that the case was fully machined, we sanded it down through all the grits: from 120 grit to get rid of machining marks, all the way up to 2000 grit, at which point the wild olive feels almost like a synthetic material. This done we could start the oiling process, which took up the rest of the week. We used the same process as I use on guitar bodies and necks: applying a coat of finishing oil (I used Crimson Guitar's finishing oil, but you can use things like tru-oil etc. to the same effect) twice a day, leaving it at least six hours to dry, and then sanding it back with 2000 grit again to get a polish on it, and repeat until happy.

Alas we ran out of time in the week to do final assembly and sign off on the clock, but we did get the case completed and Jason's taking it back, along with all the other bits we made in Makespace that week (such as the acrylic base and the 3D printed feet) and will finish it off once he's got the right screws etc. I very much look forward to seeing the final object in pride of place in Jason's home!

It was a great little project to work on, I'm very grateful for Jason letting me take part in his project and proud of what we achieved in just two weeks effectively. We went from concept to a high quality, beautiful, and practical piece very quickly thanks to a combination of rapid prototyping and both Jason and I paying attention to detail throughout. I also learned a bunch about working with another kind of material, and I look forward to applying that to my guitars in the future.


When not helping Jason with the clock case, I did managed to do various things guitar related. At the end of last week I was making another revision of the 3D printed controls for the prototype offset. Although happy with the ergonomics, I just couldn’t get the hole inside the control knobs I’d printed to mesh tightly with the knurled shaft on the control pots and rotary pickup selector switch. So I tweaked my control design and printed a new version with a hole for a grub screw in it, and I had hoped that the resin would be soft enough that I could just screw in the grub screw without tapping the hole; I was wrong. When I tried to just screw the grub screw into the hole in the resin it just split the resin near the opening and then wouldn’t go in any further.

So, it was time to skill up and learn how to tap a hole properly.  For those less familiar with this term (as I was not so long ago): tapping a hole is to make the threads for the screw to follow on the inside of said hole. In a lot of cases in woodwork you don’t need to do this, you can just use self tapping screws that will cut the thread into the wood as you screw them in. But on harder materials like metal and (in this case) resin you’ll find you can’t do that, and you need to make the threads using a tap and die set.

Once again I was reminded of one of the main advantages of a communal workshop like Makespace: when I asked Alaric, one of the regular members, about where we keep the right tools he not only pointed me in the right direction, he also explained how to tap a small M3 hole like this reliably. So 5 minutes after starting, I’d taken one of the failed prints, drilled a hole of the correct size (2.8mm for a 3mm screw) tapped it, and fitted it to a pot where it remained absolutely tight. It was very much a Matrix style "I know kung-fu" moment - going from ignorance to perfectly executed in a few minutes thanks to Alaric's guidance!


I then redid the switch on the offset with a tapped hole, fitted it with a grub screw, and it’s wonderfully secure: no more slipping when it reaches the ends of its range and you try to force it further. Very happy that I’ve learned this new skill, and that my 3D printed controls now are just as secure as they are nice to use.


Jason applied the same knowledge to the clock case, tapping the screw holes in the olive wood. Given we knew it was somewhat brittle from how it reacted when we milled it out, we felt gently tapping the holes would be easier on the wood than trying to use self tapping screws.

I’m still a little unhappy with the tuning stability on the prototype offset’s dynamic vibrato. I posted on instagram asking for advice and got a few suggestions from the kind folk there: you need at least 11 gauge strings for it to have enough tension; ensure the strings aren’t sticking in the nut by lubricating it; lubricate the posts on the vibrato; tighten the springs in the vibrato. I’m working my way through this list going from easiest to do through to more destructive (adjusting the springs will not be a nice job given how they’re bent over when fitted). But shortage of time meant I only got as far as fitting some gauge 11 strings, so I hope to revisit this in the coming days.

A lot of people tell me that the Mustang style dynamic vibrato just isn’t that stable, and that may indeed be the case, but if I’m going to sell this guitar to someone I want to know it’s setup as best it can be, so definitely want to keep at this until I know I’ve got it as good as possible. If you have any advice on setting up this style of guitar please do drop me a line!

The recovered offset body got close to finished this week when I completed the shaping that the CNC router didn’t do: I used a hand router to curve over the edges, and then using a rasp I got my monthly exercise allowance by hand carving the comfort carves on the body: the arm carve on the top and the belly carve on the bottom.


It’s a lot of effort to do this by hand, but it’s actually much easier in terms of accuracy than one might think when using such a brutal tool. I use regularly spaced pencil markings to guide me, which I refresh through out the process to ensure I almost always have some visual reference as to what I'm doing, but beyond that it’s just going slowly. This body is now done bar final sanding to remove machine marks and getting it ready to stain and oil. Having got this far, I’m now confident to cut out the delayed commission by hand rather than using the CNC router at all, which will be my first body made without using the CNC router at all. A bit of a backward step, but I’m eager to get these guitars moving and not hanging over me.

A week in the shop(s)

This week was topped and tailed by trying to better understand two CNC routers in an attempt to get back to where I want to be production wise, and the middle bit was learning to cope without a reliable CNC machine.

I started the week in Liverpool. Following on from MakeFest last week, I spent a couple of days visiting DoES Liverpool. DoES is a maker space/co-working space/event space set in Liverpool’s Fabric District, and in part I was visiting as they’ve taken delivery of a new CNC router, and I wanted to investigate if it’d be a viable alternative for me to use whilst the one in Cambridge’s Makespace is giving me grief. 

Thanks to the help of some DoES regulars, notably “Nuclear” Sean and Adrian McEwan, I was able to have a look at their machine and try it out. The machine itself is a CNCStep High-Z router with a 720x420mm bed. Despite being smaller than the one we have in Cambridge, it’s actually rated for metal work which ours is not, which is pretty cool. However, because the machine was new, it was still in the process of being set up; notably they didn’t have a proper sacrificial bed set up, and they had a limited range of collets, which meant I couldn’t use the router bits and drill bits I’d need to make guitar parts there and then. However, I did my best to help document what they had and work out what kind of collets etc. they needed to get things up and running properly, so whilst the trip didn’t lead to any guitars being made, I did do my best to try help move them forward given my time there.

My plan is to go back in a month or so (modulo the madness that will be August travel wise) to both try do some work on the router and continue to try contribute to the DoES community by running my Fusion 360 training course for their members. It will also just nice to be back to hang out with the DoES crowd - they have some great makers up there, so if you're in Liverpool I can recommend going along to some of their events and meeting the crew.

Back in Cambridge we had an unsuccessful attempt to breath confidence back into the CNC Router at Makespace by replacing it’s controller with a new one. We’re fairly convinced that all the errors we’ve seen with it are software bugs in the controller, and we found a roughly equivalent pendant controller for the router similar to the one we have. Whilst there are many wonderful other ways you can control a CNC Router, we had hoped to replace the existing controller with something roughly the same to avoid having to re-train everyone at Makespace.


So a group of us on Saturday tried to swap the controllers, and despite what we though was initial success when we managed to get the new controller and it’s breakout board installed and controlling the motors and responding to switches etc., the moment we started to try loading actual CNC g-code into the new controller it started crashing and losing its settings, which is quite dangerous on a machine like this. Thus we had to roll back to the original controller and replan.

Despite the failure, I learned a lot about how a CNC router is put together this week, so overall I feel better positioned to try help move things forward now.

Back in the workshop I’ve continued to try and get around all this CNC router nonsense by doing more by hand, so I can get these commissions done. The body that I talked about patching last week needed two more stages done to it: it needed to lose some depth, and it needed the holes put into it.

When I thickness the planks to make a guitar, I always leave a couple of mm more than I need for the CNC router to face off. Unfortunately now I’m not using the CNC router to finish the recovered body, I needed to by hand take those 2mm off by hand. Whilst it may not seem like much, this body is made from American Ash, which is quite dense, so anything I can do to keep the weight manageable is worth it. So, it was out with my trusty number 7 hand plane, a bit of time sharpening the blade, and then an hour or so of hard graft in this week’s high temperatures.


The results are great. I don’t use the plane enough to be an expert, so it took me a little while to get back into it, but in the end I had a nice flat back to the guitar and it was down to the size I wanted.

Next up was to use the templates to add the holes to the body for the neck, bridge, and through body string holes. I was a bit wary of doing this, as when I did the first guitar I did all these by hand, and whilst I did an okay job, it wasn’t nearly as good as the CNC router can do with it’s mechanical precision. However, using the MDF templates I made along with a lot of careful alignment on the pillar drill, I was able to get everything lined up and I’m really pleased with the results.


I’m now fairly confident that with the templates I have I can make a regular solid body shape by hand. The only bit that I still need to figure out is the headstock transition on the neck, which I’d just got happy with using the CNC router, as I wasn’t happy with the results of using a drum sander on a pillar drill. 

I’ve taken another pass at trying to tweak my pickup selector switch on the prototype offset. I’m super happy with the ergonomics of the switch, but The 3D printed part just isn’t tough enough to rotate the selector switch without slipping. So, after chatting with Matt at Fidelity for a bit, he suggested I should try adding a grub screw to it. Thus I broke out Fusion and tweaked my design to accommodate that:

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I had to add a rear section to the selector to give me enough depth to hide a grub screw, as before there was nothing on the back and it was too shallow. But I think actually the switch looks nicer as a result, making the selector look less like Beaker from the Muppets :). I’ve printed one out, and I’m just waiting for some pointed grub screws to arrive in the post for me to test it.

A week in the shop and in Liverpool

This week was the run-up to Liverpool MakeFest, and so the week was in somewhat dominated by preparation for that. Liverpool MakeFest is a chance for the public to come and see lots of maker projects and hopefully this will inspire them to try their hands at making themselves. As such, as I did last year, I used my stand to try and teach people how an electric guitar is made and de-mystify the process somewhat. To do this I had a table that tells the story left to right: on the left we have wood blanks for the body, neck and fretboard, in the middle we have an in progress build, and on the right we have the finished product. I then use this to guide people through the process so that hopefully they understand how an electric guitar comes to be.


I also had stashed under the table my trusty Blackstar Fly BT workbench amp, so I could let anyone who wants to have a play. Originally I planned to take the newly finished prototype offset, but I realised at the last minute that the Blues Deluxe guitar shown above was actually one of the in progress pieces I had on display last year, and that made for a nicer story for the few repeat visitors we had.

As with the year before, the day of MakeFest was nicely busy. Doors opened at 9am, and whilst the first hour was slow,  I was talking to people all day until doors closed at 5pm without much of a break. I had lots of great conversations with people about guitar building, playing, types of wood, how fretting is done, and I took fun trying to get children to see the guitar in the wood blanks (which I’d laid out in the rough shape), then talking them through the process (comparing routing to tracing on paper etc.) to the end, and then going back and seeing if they could see the guitar in the blanks afterwards, and typically they could. I really was a fun day, and I got to crank up the amp as loud as I could after close and belt out some White Stripes in a public library, just because you don’t often get the opportunity to :)

Many thanks to everyone who stopped by to chat, those who played the guitar, to Laura for helping get me set up, Jason for coffee, and obviously a huge thanks to the organisers and volunteers running Liverpool Makefest - hope to see you all again in 2019!

To get things to show for MakeFest I decided to get the failed body and neck I have hanging around into some presentable state, so they could be examples of in progress work. Last week I talked about how I’d routed out the body that was half cut then damaged by the CNC router using templates and a hand router. This week I patched up that body, and I also went through the same process of finishing the CNC router’s job by hand on the neck it damaged.

With the guitar body being fully cut out the next job was to patch the hole that the CNC router had made in the body as best I could:


A traditional approach to this would be to cut out more material to make it a regular shape and then fill it with a plug made of the same wood in that shape. However, inspiration (or insanity) struck me, and I thought I might be able to plug it without taking any more material out if I took a rubbing of the hole on paper, imported that into Fusion 360, and then CNC cut a plug that matched exactly. This crazy plan actually worked, much to my mild surprise. I’ve written up the process in full over here, but the end result is like this:

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The colour match isn’t perfect, but it’s certainly a perfect fit, so with a dark stain or painted over you’d not know that this was patched, so a great success as far as I’m concerned. I could possibly have got a better colour match had I managed to hold onto a bit of offcut that was closer to where the damage occurred, but I didn’t realise the colour of the wood changed from side to side until too late. Still, this is all important learning. 

I’m very grateful to the encouragement I’ve been given by Ray at Black Swamp Guitars and Matt at Fidelity Guitars on coming to understand that mistakes will happen as they do in any line of work, and just because you can’t hit undo doesn’t mean you give up and start again. Similarly theres just going to be defects in wood that you only uncover part way into a build, so you really do have to be prepared to react to what’s happening as you go along, and not (as I’ve been doing) despairing the moment things aren’t perfect. 

Having sorted out the body ready for show at MakeFest, the next step was to get the neck where I had my first incident of the CNC router going rouge cut out. On this one the neck was almost complete and the CNC router doing the final contour cutout stage when it decided to plunge the bit into the wood as it cut, shattering both the wood in that area and my expensive router bit. Ultimately though this is another time where the plan is to just make the hole more of a regular shape and then plug it. The trick I did for the body won’t work here as the hole really is irregular on all axis, not just a 2D irregularity. 

First step then was to use the bandsaw to cut off the bulk of the wood that wasn’t the neck, a task made easier by the fact that the router had done 3/4 of a contour pass giving me nice guidelines to use. For the rest I just pencilled around the MDF neck template I’d made previously and used that as a guide, keeping 10mm or so clear.


The neck now roughly freed I screwed on the template to the top side that would be hidden by the fretboard, and used the router to follow around the main part of the neck. This didn’t work for the headstock though, as I’d already cut away the face of the headstock, so I then had to flip things around and use clamps to hold the template on the back of the neck and clear the headstock. This done, I could now see the damage more clearly.


Thankfully it actually isn't as bad as it looks: the damage is around the 12th fret area, which means the neck will be curved on the back still at this point, so actually only a tiny amount of damage will need to be patched, not the entire hole. My plan now is to to the initial roughing pass on the back of the neck just to get a 45˚ face on the back of the neck, then patch it. However, I stopped at this stage due to lack of time this week, and the neck in the template cut state was good enough to show people at Makefest.

On the topic of necks, given my new found distrust of CNC Routers, I wondered how I’d do the truss rod channel without a CNC router; it’s easy to do the outside lines of the neck as I’d just done, but getting the truss rod channel is much harder. For this I’d need a jig, so I decided to make one.


For this jig I’d need basically two parts to it: the first part is a bit at the bottom to hold the neck snug and in a known position, and then a second part above that where I can insert my hand router and run it along with stops on all sides to ensure the only bits I cut are those needed for the channel. I decided to knock this design up in Fusion 360 and make it out of MDF. Note I don’t need it for the above neck, it already has a truss rod channel, but I just wanted to understand what was required to help me become more confident that I can make guitars without the crutch of a CNC router that will never fail.

You can see the jig above. It’s designed to be made out of 3 bits of 12mm MDF. The bottom layer has a pocket the exact shape for the necks I’m currently making, which will hold the newly templated neck in place. The second layer is a spacer, and provides a bed for the hand router to site on. The top layer is sized so that the based of the hand router can’t move side to side, ensuring the channel is straight down the middle, and it can’t move to far at either end, so the channel is just the right length. Having designed it, I then cut it out in MDF and I have it ready for action.

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I’ve always been unreasonable scared of making jigs; it seemed something quite complicated to get right, so building this was quite confidence building. Thanks to my neck design being in Fusion already, generating the jig design that exactly matched too less than half an hour, and cutting it out on the CNC router didn’t take that long either (again, although the CNC Router will occasionally fail and damage bits, I’m still happy to cut MDF on it as the cost of failure is low: I just don’t trust it to cut guitar parts as the cost of failure there is high).

The other fun project this week was working with my friend Jason, who’s visiting over from the US. Jason’s recently been working on some amazing electronics projects, including his Anytime Nixie tube based clock that shows the time of where his friends are in the world. Whilst Jason was in Cambridge we thought it’d be fun to work on something together, and so I’m helping him make a wooden case for the clock in Makespace.


The clock currently looks like the above picture: a set of boards with the 4 nixie tubes on top, and it’s powered by a USB micro port on the back. Obviously I want to design and build the base using Fusion 360, as that’s the tool I’m familiar with (as is Jason). Thankfully Jason did his PCB layouts using Autodesk Eagle, which will export the PCBs into Fusion 360 with the correct board sizes and surface silkscreens, making it really easy to get started with. I just had to model the headers connecting them and the nixie tube holders, and I’d very quickly got a mock up of Jason’s latest physical version of the clock.

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From here I then did a quick rough model of the case before Jason arrived, and then together we refined it and did a series of test 3D prints until we got a design we were happy with. It’s really quite powerful having access to a 3D printer for this kind of thing. Although I want to machine the final case in wood, that’s a slow process that will need constant watching, so quite expensive for throw away prototyping. But a 3D printer will make a case design in a few hours and I don’t need to baby sit it for that time. So we were able to go from this:

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To this:


with next to no effort. Similarly we wanted an acrylic base sheet, and designing that and getting a test cut using the laser cutters in the workshop took literally ten minutes. We’re truly living the rapid prototyping dream :)

Having got his far, the next step once back from Liverpool will be to mill out a wooden model in scrap wood, before finalising the design and making it out of some nice textured wood so that Jason has a lovely looking clock he lave running in his home without it looking like a lab experiment. 

In last week’s notes I celebrated finishing the prototype offset build, this week I sat down to try do the setup, and immediately learned why people have a love/hate relationship with vibrato units (or as they’re more commonly and incorrectly known, tremolo units) on guitars: the sound is nice, but getting them to behave is a real pain. At first I just assumed either I was an idiot or it was broken, but eventually (buried in some youtube comments somewhere) I found some advice about making the Mustang style dynamic vibrato bridge work.

The general advice is ensure the springs are as far down the posts under the bridge as possible, and that the cigar tube bit the strings are into is as low as possible too, but not with the strings touching, you want space for them to move a little. Having done this you then just tune up, use the vibrato (not gently either, but also not dive bombing it), at which point it’ll go out of tune, and then you tune again and repeat until things are roughly stable. Even at this point, I still find it goes out of tune more than I’m used to, but at least I can get through a song using the vibrato without being out of key.


How to plug a mostly-irregular shaped hole in wood using Fusion 360

Regular readers will know I’ve had a bit of bad luck with the CNC router this last year, the latest of which was where the router unexpectedly decided to cut into the body of a guitar when it was supposed to be cutting the contours, ruining the body like so:


Whilst this body is now not fit for its original purpose any more, as that guitar will have a natural finish, I’m keep to try patch this error and make something from this body given the time and expense that has already gone into it. Having finished the CNC routers job of cutting out the rest of the body by hand using a template and a hand router, I wanted to patch up the hole using a bit of left over wood I had from when I cut the body out.

The typical approach here would be to cut a more regular shape out of the body and then plug that, so (as suggested by Ray over at Black Swamp Guitars) I could have used a wide spade bit to drill out a circular area and plan plugged that with a circular plug. Basically you’re trying to make the problem simple with this cut then patch approach, as patching irregular shapes is very difficult. However, for fun, I wondered if I could somehow model the area cut out here, as whilst it’s not as simple a shape as a circle, it is a series of clean curves made with a router bit of a known size, and it’s also nicely uniform across its depth due to how it was made: thus if I could get the top 2D profile then I could just extrude that to make the plug.

To make the plug, I first did something I’ve not done since I was a child: I got some paper and a pencil and took a rubbing of the top of the guitar in the area where it went wrong.


Having done this, I then scanned it and imported it as a canvas into fusion:

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When you import a canvas Fusion doesn’t know how big the image is (it appears to ignore the DPI information in the image header alas), so the next thing I did was make a couple of reference construction circles in the sketch with the canvas, the diameter of which was the diameter of the bit the router was using when it went rogue (in this case 1/4”). Having got those two circles I positioned one so that it was roughly where the inner sweep was as the router cut in, and one in it’s final resting place, and then I could use that to start resizing the image canvas until I was happy I had the image to scale. Once that was done I used the Fusion sketch tools to draw the outline of the damaged area, with a little extra sticking out the side:

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This done I could then extrude the entire shape, and now I have a design for a plug that in theory should perfectly match.

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Having got my design, I then made some CNC router toolpaths, and I did an initial test run using a bit of scrap ply I found in the workshop. The result wasn’t bad, a lot better than I expected in fact give I was just basing this off a rubbing I'd made!


The spacing wasn’t perfect though, so I went back to my design and added an offset outline of a couple of tenths of a millimetre, and the next plywood test plug I cut, with a little sanding on the side, fit snug. Satisfied with that, I then went to my ash offcuts and cut a taller test plug, which still worked, and finally I did a 4th and final plug where I matched the grain of the wood as best I could to the surrounding area where it was going to sit. Again, after a little sanding, it fit perfect:


Obviously when I say fits perfect you can see I have overhangs on the top and side, but that’s deliberate: it’s much easier to level those bits with a hand router and sanding than it would be to cut it perfect at this stage. Having got a plug that matched as best I could, I glued it in, left it clamped over night, and the next day trimmed the excess off, the result of which is a nicely plugged hole:

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Whilst the end result is still noticeable in terms of colour at this stage, if I paint this body or even use a dark stain then you now won’t be aware that any damage was done and it had to be patched. I’m looking forward now to finishing this body off and turning it into a guitar!

A week in the shop

Important reminder up front that I’ll be at Liverpool Makefest this coming Saturday, with a stand explaining how I build my guitars and now you could to. I’ll have some guitars and in progress bits on show, and look forward to meeting people and trying to help them see how something like this can come together. I had a lot of fun doing it last year, and look forward to meeting people this year too.

I’ve also had my talk proposal on how to get started in a new domain accepted for EMFCamp later this year, which I’m looking forward to too!

The prototype offset finally came together this last week, which has been a much welcome confidence boost after all the setbacks of the last few months.


The start of the week was doing the final assembly, which was a little slow due to this being the first guitar I’ve built from this CAD design. It’s the little things such as the tolerances for things that need to fit snug needed a little final tweaking; I’d made them small in order to be conservative (as you can’t add as easily as you can take away), and so the fittings for things like the thimbles that hold the bridge in place and the ferrules for the tuning pegs all needed a little sanding to remove a half millimetre or so. to get them just right. This is a slow process, and quite hard on the hands: not having a proper tool for the job (as I didn’t realise there was one) I was using sand paper wrapped tightly around a drill bit, with lots of care being taken not to scratch the finish.


It turns out there is a tool called a reamer which would do this job, so next I’ll hopefully be able to do this quicker. Because I am using vintage style tuners, which have a stepped hole, I didn't think I could use a reamer at first, but you can buy two tier ones from StewMac, which is good to know (many thanks to Leddington of G Leddington Guitars for educating me on this!). That said, I’ve also gone back to my CAD model and adjusted the sizes of these holes now I know that they need a little more room. Still, the end result was a nice snug fit for both the ferrules and the thimbles.


I also drilled all the final holes for mounting the pick guard, the strap buttons, and the control plate. It’s always somewhat nerve-racking to take a drill to a nearly finished guitar, but  again you just need to be slow, and I find starting with a small drill bit (say 1 or 1.5mm) and working up for the bigger sizes always pays dividends in ensuring that your holes are where you want them,  and well worth the extra time.

The little gauge I was printing last week to measure pot shafts came out nice, and I’m glad I extended it to a full millimetre larger than the described shaft size as in the end for the pickup selector that’s what I needed


Thanks to that I was able to print a first set of controls for the guitar on the Formlabs FormOne printer here at Makespace. Once printed I wasn’t happy with the finish of the print itself, so I took time to sand it like I did the body, going up through the grits from 240 to 2000 before finishing with wire wool (to get into the tighter gaps) and the end result is lovely. I have however had to print a second batch. The pickup selector hand’t cured properly inside, and that selector switch is quite stiff, so in the end I ruined the teeth. The volume and tone controls worked fine, but I felt they sat a bit too high, so I reworked the design to have more of a hollow underneath and made them taller. I’ll try fitting them this coming week.

Otherwise the guitar came together well: for once I got the electronic soldered first time, despite switching from leaded to unleaded solder: for things I'm not selling I've been using leaded solder as it's easier to work with, but now I'm going to start shipping these guitars I've had to switch to unleaded which is harder to work with. Still, it fired up first time:


It still needs final setup, but I'm really pleased with how this guitar has turned out. The swamp ash body has a wonderful light weight to it (thanks to Matt of Fidelity Guitars for turning me on to swamp ash), the House of Tone Mustang pickups sound great, and I'm pleased with the pickup selector which has four positions giving me neck, bridge, both in series and both in parallel. The pickups are wound in opposite directions so in the combined positions you get a nice noise cancelling humbucking effect too. I also really like the scale length, which is very comfortable to play.

Now I just need to finish setting it up. That sprints for the dynamic vibrato need tightening, as it loses it’s tuning unless you pull back after using it, and the nut/bridge height need tweaking. But otherwise really pleased with how it’s come together. Now to get the commissions done, which actually will benefit from the learnings I’ve had on this build.

Whilst most of the week was working on the prototype offset, I finished routing out the body I roughed out with the bandsaw last week. I used the templates I made a few weeks back and ran around the edge getting the profile finished. It was slightly complicated by having to avoid the area where the CNC router took a chunk out, and I only had a 24mm long bit at the body depth is 41mm, so I had to template from both sides in the end. But it’s now done and the next task is to plug that hole.


A week in the shop

Last week I thought I’d finished the oiling of the prototype offset, but I was wrong. I’d assumed the wenge fretboard on this would be treated just like a rosewood fretboard: I’d use a specific fretboard oil (e.g., lemon oil) to preserve the moisture in the wood, rather than a gun-oil type oil to lacquer it like I would a maple fretboard (as indeed I do for the rest of the guitar). However, I tested the fretboard oil on a scrap bit of wenge before applying it to the neck, and much to my disappointment it it removed all the nice two tone colour that wenge has, all going a uniform dark brown. I had a chat with Matt over at Fidelity Guitars, and he confirmed that he treated wenge more like maple than rosewood, recommending a few coats of a gun-oil to give it a thin lacquer.

Thus the neck was remasked to let me oil the fretboard, which I did over a few days, and then I’ve left it a few more days to cure. The results are worth it: the fretboard now is nice to touch and has preserved the two tone effect of the wenge.


I think the only thing that I'm disappointed about on this neck is the clay inlays, which I did as an experiment to see how they'd work compared to using plastic inlays. Overall they fit, but they have been stained somewhat by the wenge dust as I've sanded the it back, and it's not quite the finished I'd hoped for. So somewhat a success but I think in future I'll try something else.

Whilst the neck was curing I went to mill the pick guard for this guitar on the CNC router. Unfortunately, the run did not go as planned, though for once it was not the machine that was at fault, and rather my inexperience of working with PVC and doing chamfers with the CNC router. 


The above picture shows my attempt to chamfer the holes where the mount screws would go on the pick guard (this was the first stage of cutting it). All the holes should be the same size, bar the few on the bottom left where I was testing cutting the PVC, but as you can see they vary in diameter wildly. This is because the PVC is flexible, and even though I’ve screwed it down to the bed the surface of the PVC isn’t perfectly level, which causes this variance. 

To make a chamfer you use a tapered bit, in this case I had a bit that had a 90˚ angle at the tip, like so:

IMG_0272 2.jpg

The depth at which you insert the bit into the material will dictate how wide the overall hole will be: as you push the bit in more the taper means the bit touching the material is wider. Unfortunately because the PVC here isn’t absolutely flat you end up with contact points at subtly different heights which means different sized holes, which is clearly not what we want. Even if I’d done a better job of pinning down the PVC I’m not sure I could totally eliminate this without ensuring the bed on the router is perfectly level and the PVC uniformly thick, so I think I’d need to chamfer the plates after cutting next time using some other method.

Given I’d ruined this material and I want to get this guitar finished, I decided to try a very different approach: I found some snazzy laser cutter safe material and made a scratch plate out of that:


This has a totally different vibe from what I was planning, but I’m quite pleased with the result for now. We’ll see how it looks when assembled: I can always change this easily later. It was quite nice to do prototyping timeline on this:


Left to right, that’s the first paper version cut on the laser cutter to check general sizes, the cardboard version I cut to mount the pickups and selector on to make sure they all fitted, and then final acrylic version also cut on the laser cutter. I often tell people to measure, measure, cut, and this is a nice example of that principle in practice :)

A little while back I did a test print of my own control knobs, and I realised this week I’d not bought any for this prototype offset, so I’d just make my own. It doesn’t offer a particular cost saving, particularly when you factor in time, but it’s nice to have yet another personal touch to a guitar. 

I started by making some mockups in Fusion 360 and printing them using the low resolution Ultimaker just to ensure I was happy with how they feel in hand and in context on the guitar. There’s two designs: one for the volume and tone controls, and another for the pickup selector dial, which I’ve modelled slightly on the one used on the Fender XII selector.


Having got the low resolution printouts made and I'm happy with how they feel, I can now do a high resolution printout with the FormOne printer, but first I need to know how bit to make the toothed hole inside to get a good fit. Although notionally pots have a 6mm toothed shaft, I’ve found in practice they vary a little, and this is important if you’re just going for a friction fit. So I made a little gauge and printed that out.

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This gauge has 0.2mm increments from 6mm to 7mm diameter, and I’ll use that on each pot to work out the best size and then print the control to match that measurement. The taper on one end is there to remind me which end has the smaller hole on it.


This is the print just out of the FormOne, before I’ve cleaned it up using a IPA bath and then done the UV curing to harden the outside. 

Following on from my plans last week to try and make good on some of the failed parts, I took the body that the CNC router had cut into and did a rough pass to get rid of most the unneeded wood, ready for trimming it using the templates:


I also cut a third offset template, this one with the holes for a dynamic vibrator, so I have the option of making it a fixed bride or a vibrato unit. I also made sure to put the control cavity in this template, as I accidentally forgot to add it to the last set I made!

Lastly, my OMEC Teleport arrived, and has been installed on my pedalboard.


I’ve not played much with it, but I can conform it plays nicely with the iPad, but you do need to get the iPad Camera kit adapter (which is almost half the price of the Teleport itself!) or some other USB-B to lightning cable (it ships with a USB cable only). I tried it both with my own ongoing audio filter project and with Bias FX.

It amuses me somewhat that of my 5 pedals 3 of them have a USB cable sticking out the back to let me play with them in one way or another.

A week in and out the shop

This week has been a quiet week in the workshop. At the start of the week the prototype offset was at the stage whereby it just had a coat of oil on the body and neck once a day, and then since I’ve left it a full week to cure properly. In the coming days I can get back into action doing the assembly and cutting the pick guard etc.

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As mentioned last week, I realised I can't laser cut the pick guard (as most pick guard material isn't laser cutter safe), so I'll have to mill it instead. Given I was milling it I've ordered a 60˚ angled router bit so I can chamfer the edges properly. Last time I tried to use the CNC router for this kind of thing the material cracked around the spaces near the screw holes, but I'm confident this time I'll have better success as Fusion 360 lets me control things better than the tools I used before.

In prep for heading up to DoES Liverpool next month to use their CNC router I started the process of getting all the wood ready for that trip. I need to make a new body blank to replace the one that was destroyed by the errant router at Makespace last time, and I have had for ages a bunch of nice wood sitting around ready to make the necks for the two commissioned offsets. The first stage was to thickness all that wood, and I once again took the kind offer of a friend to let me use his thicknesser.


At the moment I’m feeling that the number of guitars I’ve generated is very poor for the amount of times I’ve used this favour. Hopefully we can start to put a dent in that. 

I really feel that as we reach the mid point of 2018 I’ve not had a successful first half of the year: I’d hoped to have made three or more guitars by now, but it looks like I’ll only have managed one guitar, the amp, and a bunch of harsh lessons about things going wrong. It’s very easy to let setbacks cause you to lose momentum, particularly when you have other things you need to do to pay the bills, and I look back on the first half of the year with a sense of having got distracted and not kept up pace.

To try and offset some of this (pun not intended), I’ve been looking at what I can do to try and turn some of the bits I have left over from failures into an actual guitar that I could ship as a sort of factory second. I have two bits that immediately come to mind as things I can try spruce up. Firstly, I have the neck where the fretboard didn’t glue on perfectly, leaving it with an obvious seam that meant I couldn’t use it. I think with this I could either go for an edge binding to cover the seam, or I could try perhaps heat it up to melt the glue and remove the fretboard entirely and try re-glue it. I bought some binding material, but the standard sizes it comes in of 1/4 inch is not quite deep enough to reach the seem without having to have a couple of mm off the fretboard top itself. Anyway, as other things move forward I shall see if I can find a way forward here - suggestions welcome!

The second bit is the body that the router ruined that was meant for one of the commissions. It now has a large gouge near the upper horn from there the CNC router decided my design wasn’t interesting enough, and it had a better idea. What I’d like to do with this is fill in the gouge and finish cutting the body out with templates. It’s not going to be useable on the commission, as it’ll be an obvious flaw - the guitar will be finished in stain/oil and it’d show through. But after filling I could paint this one to hide it, or I could follow the Kintsugi philosophy (on both this and the neck actually) and fill the area with a gold resin, and make it a feature that tells the tale of the troubled build process (a hat tip to my friends Marine and Dom for that suggestion).

My problem is that I’m a perfectionist about the guitars, and I want them to be flawless, and when I fail to hit my mark I sort of shy away from things for a bit as I lose my confidence that I can achieve what I want is dented. This is something I need to try come over, as its an inherent part of learning and getting to grips with hand crafting physical objects.

As part of trying to continue to develop my manufacturing skills by tackling some smaller projects I bought a cheap effects pedal kit and set about designing a case for it. Currently I’ve just started with a traditional shape, but eventually I’d like to do something less uniform in its shape and 3D print that.

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Strength will be the main issue with anything 3D printed, as in the heat of the moment effect stomp boxes probably take quite a hammering. But this is mostly as an experiment, and if it fails I’ll have learned something and I can just use the metal enclosure that shipped with the kit.

I also spent a couple of days this week refining the audio effects software I was playing with last week, trying to shape it into something that is more practical to let me (and potentially others) experiment with. There’s a saying in software that once you’ve finished 90% of the product you get to do the other 90% - a reference to the fact that the interesting bit you care about is what  you think will take most of the time, but is in fact only half the problem, and you still have to do all the dull and tedious bits to make it usable by people. I spent some time this week on tweaking my software so I could save my effect filter experiments and share them between all my iOS devices. allowing me to work on them both on my phone and tablet seamlessly. It’s been a long time since I wrote iOS software in anger, and thus a lot of time was just trying to get back up to speed on this. 

I’ve been testing using an old iRig2, which is great for travel, but is very frustrating to use most of the time with my pedal board, as it requires long heavy audio cables running up to my iPad and back to the board. But this week the Orange OMEC Teleport finally hit the shops, which is effectively an audio card in a stomp box, which then has USB out the stomp box to your phone/tablet/laptop. So to try and stop me going crazy due to tripping over cables I ordered one of these to make it easier to test.


A week in the shop

This week I made progress on the prototype offset some more, found a potential alternative CNC router option to help me move forward on my backlog, and played around a bit in both Fusion 360 and with some DSP code.

One of the things that I’m embarrassed to say took me a while to get used to was the idea that wood isn’t perfect. I come from the world of electronics and software, and whilst you can argue that software is often far from perfect, from an engineering perspective it does at least let you generate pristine things. So it took me a little while to get used to the idea that I couldn’t just reject a bit of wood because of some tiny flaw; if I did that I’d have no wood to work with. You have to work with these flaws and find a way to hide or embrace them.

The first thing to do is when you get your wood is be selective about which bits you keep and which bits you cut out: can you, for instance, position a knot in the wood such that it’ll end up where the pickups or neck pocket will go and you’ll route it away? But even after that, you can still be taken by surprise as you peel away the layers of the wood as you guitar progresses, you’ll often find hidden features that you didn’t expect. On the fretboard for the prototype offset I'm finishing up at the moment I found this hole as I trimmed the board flush with the neck profile, where some insect has buried its way into the tree.


Thankfully, it turns out that fixing small things like this is relatively easy. All you need is some wood glue, and some sawdust from the wood in question: either from as you process the piece hold on to some, or from an off cut that you held onto for this circumstance (which is what I did here). You can just mix the sawdust until you get a fairly viscous paste (like a cement) that you then pack into and over the hole.


Leave that to dry overnight, and then you can sand it back flush with the rest of the wood.


You’ll still notice a mark there if it you go looking for it, but no more so than any other bit of figuring in the wood, and once oiled you’ll hardly see it. You can see more details on how to do this in this video from Crimson Guitars. This was my first go at this sort of repair, and I’m quite pleased with the results.

In general this week has been slowly applying finishing to the neck and body of the prototype. This is a mildly frustratingly slow stage where you apply a coat of stain or oil once or twice a day and there’s not much else you can do. I started the staining at the end of last week, and I was using a yellow stain, which after half a dozen coats has gone a wonderfully deep orange peel/sunset orange. It’s not what I expected it to do, but I’m still rather pleased with the results so far. This here is a stop motion of me applying the first coat:

I’m now four coats of oil in, with two more to go.


Once the final two coats are done, I'll leave it for a week to properly dry, and then I can cut the pick guard and wire it up.

Speaking of pick guards, I realised that my plan to laser cut the guard wasn’t going to work. Although it’s been great for prototyping, all the plastic suppliers I’ve found for traditional scratch pick guard material supply them in PVC or other such plastics that I can’t laser cut in the workshop I use due to the toxins they would emit. So instead I'll brave using the CNC router for this instead.

Speaking of CNC routers, in a bit of a breakthrough, I’ve actually found another CNC router I can try using. Regular readers are probably sick of this by now, but to recap: I’ve always made guitars using the CNC router at Makespace to rough out the bodies and ensure things like string holes are perfectly positioned. Unfortunately this year the router has started to go senile, and has twice destroyed bits I was working on, costing me both time and money. More distressingly it’s put me quite a bit behind schedule on a pair of commissions I’ve had. Whilst the CNC router at Makespace will get fixed eventually, that doesn’t help me in the near term: it being a community workshop means this process will take a little bit of time.

I was just about to start making the new guitars with a template technique rather than CNCing, when I was connected with the people up at DoES Liverpool, another community workshop that serves the Merseyside area. They’ve just got a new CNC router installed, and given I’ll be up in Liverpool for MakeFest at the end of June I plan to stay on for a few days to visit DoES and see if their machine will help me get these builds back on track. For me it's a way to get back in motion, and for DoES it'll be useful for them to have someone experienced with CNC routing show them what is possible with their new bit of kit. Very excited about this!

I revisited the guitar design I was working on a couple of weeks back a bit this week, trying out some new techniques to design the arm carve on the symmetrical guitar I was designing a few weeks ago.

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Last time I played with this I tried to model the arm carve using a mesh in Fusion, which I found very hard to work with for this kind of application. A friend of mine, the very talented Tom Armitage, who has also dabbled in Fusion 360 quite a bit, suggested I tried using a technique called lofting, where you can get Fusion to generate shapes based from a set of intermediary sketches, and it can do those shapes following a defined curve. You can see a prototype version I did below: here I sweet between two small arced corners and a larger one in the middle, following the edge of the disk.

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Now if you look back at the picture of the guitar body in Fusion above, you can see how I did the same thing on the guitar, just using points for the ends rather than corners. Really pleased with this technique. I’m still not sure about this guitar design overall, but it’d be nice to get it completed so I can then move on to something else, and the experience with this one will help with future designs.

One thing I’m fascinated by is trying to understand where the sounds I like come from and how I can, through a combination of guitar design choices, amp design choices and effects pedal choices get the sound I have in my head to come out of the speaker. To help with this I’ve been leveraging some of my other skills, and I coded up some simple audio filtering software for my iPad to let me tweak my guitar signal.


Whilst I watch things like That Pedal Show where they try to explain how things impact your sound, there’s nothing like experiencing yourself. Whilst I could make some silly and whacky sounds with my little bit of software, by far the most interesting was just playing with low and high pass filters and EQ effects. If you’ve never ran your guitar through an EQ unit, I highly recommend you do so, as it’s amazing what impact on the character of the sound from your existing setup that can have. If you want a guide to help you get started then I can recommend reading these notes by a sound engineer on how different EQ ranges impact different instruments, but again I'd say just go play with it, as I’m fairly sure you’ll be amazed what you can do with it.



A week in the shop

This last week has been a productive week, with lots to talk about, so let's get to it.

As mentioned last week, given the issues I’ve had with the CNC router I have access to, to be able to make progress again on the commissions I have I’ve decided to switch to using templates to get the rough shaping done. Last week I designed the templates in Fusion, so I started this week by cutting them out:

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Obviously this time the CNC router played ball, but I still don't trust it with anything critical (or at least cheap to replace like this MDF). Now that I have the templates the next stages are to make a new body blank for guitar #5, and to practice making the string holes and bridge mounts via a template. Clearly it’s very feasible to do this, as this is how lots of luthiers without access to CNC make guitars, but I need to just practice using the pillar drill with a template to line things up precisely.

I made progress on the demo offset I’ve been making. I’ve set myself the goal of getting this done before Liverpool Makefest (where I'll be explaining to people how guitars are made), so I can have something non-t style to show. I spent a lot of time with sand paper getting the body just right before starting to apply the stain. You can’t rush this stage if you’re going to stain/oil finish on the wood, as any scratches you miss will show up clearly in the stain, even if you couldn’t spot them before. So it’s a lot of starting low, and working up through the grits, from 120ish up to 2000. It’s really amazing how the texture of the wood totally transforms as you do this.


All sanded down I went with a yellow stain for the demo offset. This guitar will have a traditional mustang style vibrato bridge and single coil pickups, and I think a nice bright and fun colour will go with what should be a bright and fun guitar. Currently it’s four coats in, of what is normally six coats of stain, which will be followed by another six coats of oil. This is the slow stage of a guitar build, as you can only do at best two coats a day really, and partly why I like to have multiple builds on the go.


I also mostly finished the neck, which was roughly done, but just needed the polish to get it ready to oil when I start oiling the body. There was a lot of sanding here too, and I also needed to put the logo onto the headstock. In the past I made the laser etched logo in a slightly adhoc fashion: I exported the Electric Flapjack logo in DXF from Adobe Illustrator, and after many goes at getting the right export settings would be able to import it into the laser cutter software we have at Makespace. Then I’d guess a size based on measuring the space on the headstock, and after doing some trial runs on off cuts from the neck, line up things by hand on the laser cutter bed, and then hope I got it right :)

This time however I was able to improve on things, thanks to moving the whole task into Fusion 360 and having the logo as part of my CAD design. First I exported the logo from Illustrator as SVG and importing that into a sketch in Fusion 360. There I could size and position it in Fusion before making it part of my neck design:

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Now there’s no guessing involved: I can see exactly how the the logo is going to look, and adjust the position, angle, and size all I want until I’m happy in Fusion. That done, I then generated laser cutter toolpaths (as explained in this post) for both the logo and the headstock itself:

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Once I imported these into the laser cutter software, I taped some paper to the bed of the laser cutter and scored the outline of the headstock into the paper and used that to position the neck on the cutter bed before doing the etching itself:


As part of the etching you end up with a sticky residue on the surface of the headstock where the maple has burnt, and but with a little bit of sanding that all clears up nicely, and you have the finished product:


This done I’m almost ready to oil the neck, I just need to tweak the frets a little again as I sanded down the sides of the neck a little and they need refinishing.

Finally, I also spent some time over the weekend doing setups on the guitars #1 and #4, both of which I still play regularly (indeed, I don’t play anything else). Both had seen quite a bit of playing since I last gave them a service, and they were in need of a little TLC. The rosewood fretboard on #1 was starting to dry out a little, so I removed the strings, gave it a clean with some fretboard cleaning fluid I had to remove the gunk that builds up from lots of sweaty rehearsal room sessions, and applied some fretboard oil. Between that and a fresh set of Elixir Polyweb stings it plays like new:


The neck of #4 being a sealed neck hadn’t dried out but needed a clean and a bit of a general check over as this was its first service. I tightened up all the pots again, adjusted the pickup heights a little, and also gave it a fresh set of the same strings.


Whilst adjusting the the pots I accidentally rotated one so that it shorted against the copper shielding in the body, causing the bridge pickup to drop out. It took me an hour to figure out the cause, but was easy to fix (and apply some masking tape over the copper shielding to prevent it happening again in future). Tele style guitars have really compact control compartments, something I’ll avoid on my own designs!