A week in the shop

Making guitars is hard, which is also what makes it intersting and rewarding; I suspect this is true of most things that one chooses to apply oneself too. I know that's why I enjoy working in software and hardware so much. Like software and hardware though, it's very easy to get ahead of yourself and forget how hard some things are after some success (this is why software engineers are classically so bad at making time estimates).

With the prototype guitars, this month was when I finally admitted that doing the offsets was different enough from the t-styles I made before that I was going to end up assembling both a prototype body and neck before cutting wood on guitars #5 and #6. I was already building a prototype neck with cheaper wood, for the sake of a week or so I may as well do a trial run of a body. So it is I'm now assembling guitar #7, a prototype offset that will act as a guide for guitars #5 and #6.

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This won't add too much delay to guitars #5 and #6, as I don't need to finish guitar #7 off to a high standard immediately, I just want to get it to the point where I've strung it up and checked it makes notes and the intonation is correct. The electronics and the final finish are bits I'm familiar with and I can do after guitars #5 and #6 (or at least alongside for the finishing stages, as that bit is so slow anyway).

When I set up the prototype series, the idea was I was already well versed in making t-styles, so it'd be a fairly quick and easy job to do a couple more. Due to what customers asked for, I ended up not doing t-styles, but rather these to being offsets, which has pushed me a lot more, and has been fun and interesting. But with the additional troubles caused by machine madness this last month and the gluing failure, my confidence has been knocked a little, and I want the guitars I ship to my customers to be the best guitar I can build. So to remove my doubts about the new design and process, I'll apply what I preach with measure, measure, cut: guitar #7 will let me be confident that guitars #5 and #6 will be as awesome as I expect, and more importantly, as awesome as my customers expect.

Overall the impact will be a minimal delay on starting on #5 and #6, all being well, but I'll be a lot happier in the end result, and over the lifetime of a guitar a week or so is not that significant. It'll also cost me a bunch of money to validate the design, something potential luthiers should factor into their costs better than I did; but eventually #7 will become another demo guitar, which is handy as one of my demo guitars just shipped out.

I really don't like delaying guitars #5 and #6 more than they already have been with the CNC router adventures of the last few weeks: I'm acutely aware I have people waiting on me, but I'm also not going to ship something I'm not happy with, and this extra prototype will let me get there.

So, that explained, let's go see what progress we achieved this week.

At the end of last week I'd got the prototype neck to the stage where it was glued and the fret slots cut. This week I moved it through until all that remains is the fret levelling and shaping.

First up, the inlays. Normally, if you're going for traditional dot inlays on a dark wood the neck, you'd just buy some plastic pearlescent disks and glue them in, which does look lovely (I did this on guitar #3), but if you look at the vintage guitars they used clay inlays, and I've seen quite a few custom guitar builders do the same of late. I was interested to try this technique and see how it works, and the prototype neck seemed a good opportunity to give this a whirl. There's two approaches one could take here: make the inlays apart from the neck and glue them in, or drill the inlay holes in the neck and fill them with clay and sand them down. I opted for the second approach, as it felt like less steps, and in the future it might be nice to do unusual shapes, where moulding the clay into the neck would make more sense.

Before applying it to the neck, I did test this technique on a scrap bit of wood. I drilled some 5mm holes in the wood and filled them with some air drying clay (with the best will in the world, one probably shouldn't fire a guitar neck, and besides, it won't fit in my oven ;). This is the scrap immediately after putting the clay in:


Then after leaving it to dry for 24 hours I sanded it down and I got this:


I'm quite pleased with the results, though it'll be interesting to see how well it wears over time. Still, I was happy enough that I applied this to the prototype neck I've been building.

Inlays sorted, I then went on to hand carve the neck. I used to fear this bit when I started, but now I've done a couple, I really enjoy the process of hand shaping a neck. In theory could do this in Fusion 360 and get the same result, but it'd take me several goes before I could know that the Fusion design felt right in my hand, whereas with hand carving the neck I constantly take both quantitative measurements with callipers and qualitative measurements with my hand to check it feels right. It's amazing to me how much a change of just 1mm on the neck profile will lead to a completely different feel in the hand. 


The back of the neck carved, I then radiussed the fretboard down, really bringing out a wonderful pattern in the wenge. It was also here that I sanded down the clay I'd put in the inlay holes I drilled to finally see how the looked in a real neck, and they look great to me. 


The final stage here was to fret the neck. I went into this bit full of confidence, and it was at this stage that I was knocked down a peg or two (sort of the inverse of how I feel about carving the neck). This was my 4th fret job, so I thought I was getting to be an old hand at this, but immediately I was struggling, with the very first fret refusing to go in and making a mess of the nice clean fret slot I'd cut. On reflection I'd done several things wrong, which I'll share here to hopefully save someone else the frustrations.

Firstly, I'd not fretted a neck for a a few months, and you forget just how hard you have to hit them to get them home. If you're about to do a fret job and haven't done one for a while (or at all) I'd strongly recommend getting some scrap, ideally of the same wood as your fretboard so it has the same hardness characteristics, and just knocking some frets in. You spend so much time being gentle with the wood on a guitar to protect the finish, having to really hammer hard the frets in feels (at least to me) alien and wrong. But if you don't they won't go in neatly, and there's a risk they'll start to deform the fret slot if you've not got them lined up perfectly. Swift, very sharp, taps are the order of the day here. It took me several frets to get back into the swing of things.

Secondly, I'd over radiused the fret wire, making my life harder for myself. Fretwire ships at a very shallow radius (about 12" or so). Ideally you want your fret wire to have a slightly tighter radius than that of your fretboard: this means you can then tap in the two sides of the fret wire into the slot, before just tapping the middle home. With this fretwire I made it a tighter radius than I needed, so I had quite a bit of more work to do getting the centre home, which means the sides are having to shuffle more than ideal. Basically I made things hard for myself here, so don't make your fretwire radius too tight.

Finally, I'd never used wenge before on a neck. Wenge is a funny wood: the two colours you see on it are very pretty, but one is quite soft and one is quite hard. The hard bits didn't want to give when I hammered the frets in, and the soft bits were happy to deform any time I struggled. Urgh. With the previous necks the wood had been quite uniform in nature, and that seemed to help. Wenge is definitely usable and it's just me not being experienced that is the issue here, but then that's another reason to practice on scrap before you try on a real neck.


Anyway, after much stressing and sweating, I got all the frets home and reasonably level. First job for next week is to level and polish the frets so I can then put this neck on the prototype body, and string it up to check my measurements are as good as I think they are.

Given the issues with the CNC router, I was still a bit nervous about how well it'd cope on a longer job, despite the fact it'd cut the neck well, so I decided to cut a test run body that cemented the idea of building guitar #7. This is very similar to the body for guitar #5, but rather than use a hardtail style bridge, which I think is actually the better choice for a working instrument of this style (and this is probably why hardtail are the only option Fender make any more on this type of guitar), I opted on this one to go for an old style dynamic vibrato bridge with a floating bridge and tremolo arm. Why do this? Mostly just because of learning: I've at least made four guitars with fixed bridges, and none with floating bridges, so given the opportunity I thought I'd go with the termolo. From a making of the body point of view there's only a very minor change: rather than drill the string holes through the body and bore out the ferrule holes on the back to seat the strings, you instead carve out two cavities for the springs on the bridge, and bore two holes to hold the pegs for the floating bridge. The complex bits of the body, the overall outline and the cutaways for the comfort curves, remain untouched.

So, design tweaked slightly for the new bridge, I set about making my first offset body in wood. Making a guitar body on the CNC router is a two stage process, as you need to do both sides in separate passes. To make sure everything is aligned you use a technique called pinning: you drill four holes equidistant from the center of your design in the corners of your material on the first side, then when you finish side one you remove the material and drill the same four holes in the CNC router bed, put metal dowels in the bed, and mount your material the other side up on those pegs. Now your design is perfectly lined up for you to do the second side. I'd always advocate doing the pinning holes first, as once you've made these, you can even abort your design run and come back another date: although the origin on the router may change, so long as you have reference holes on your material you can always make new reference holes in the bed and get back to a know position. During the making of this body about half way through the first side I knocked the material out of the mounts I was using, but because I had already made the pinning holes this wasn't a problem, as Just flipped it over, made pinning holes on the other side, and then could get back to being properly aligned. 


It took 5 hours to route the body, tweaking the Fusion toolpaths as I went. This is the first full body I've made from Fusion and the first time I've routed one with properly 3D surfaces, so it required a bit of reworking as I went along. After that it took me a few more hours of sanding and tweaking with hand tools to get to the shape I wanted. I don't do everything in Fusion, there's still quite a bit of hand work I do to the body afterward to get it just right: I rounded all the edges with a hand router, I adjusted the comfort carves to be just right using hand rasps and sanding, and so forth. Oh, and lots and lots of sanding, as the routers never give you a perfectly smooth finish.


Although it worked out all good, it was much more relaxing to do this on a non-customer body, and I'm now ready to cut the bodies for the customer guitars. The only thing holding me back is just double checking that I've got the intonation right by finishing the prototype neck and stringing it up. 

The one other thing I did this week that took up a bit of time to prep for was I ran a class teaching Fusion 360 to other Makespace members. I taught 10 people how to use Fusion to make a simple device (a kitchen roll/tape dispense) and then how to fabricate it on 3D printers and the CNC router. 


I did this mostly because people had asked, but it is also good for me: the more expertise there is using Fusion 360 in Makespace and the more people use it to target the machines in Makespace the better it'll be for me when I get stuck and need help. I've already seen people who were in the class doing things in Fusion I've never tried, which is great!

The little blue amp demo video

Somewhat belated, but here's a small video of our first amp build, the little blue amp, a small 5 watt tube based amp for home/rehearsal use:

The content isn't great, as I was a bit rushed that day trying to do too many things, but hopefully gives you a good idea of how the amp works :) My thanks to Tristan for salvaging something from the mound of video I recorded; next time I'll get him to film the lot :)

A week in the shop

This week I've been trying to regain momentum. Between the issues with the CNC router that derailed me, and being under the weather for most of last week, I started this week with a strong sense of not having made much progress, so this week has mostly been about trying to regain traction.

The CNC router at Makespace is still a bit of an unknown, but the fine people there have been digging in more, including doing full checks on the power supply in the workshop, and how it behaves when other machines are turned on, etc. That all looks clean, so it could start to be a software bug in the router perhaps. That said, the cables on the machine are all a bit the worse for wear, so we're going to replace them. Turns out our CNC machine uses a 50 pin SCSI connector for the controller to talk to the motors, which is quite weird. But a new one shall be ordered shortly. But for now, I think it's just cautiously back to business as usual.

At the end of last week I got to the point I wanted to be about three weeks ago now, where I'd cut the parts for a prototype run for the neck for the pair of offsets I'm making. The first prototype hadn't glued properly, so this was a second one to try again. Given I've made necks before, why am I prototyping? The reason is that I'm trying a new design with a nicer truss rod access, and I'm trying to glue the fretboard on after shaping rather than before, as that makes things like shaping the headstock transition easier, as I can rough that bit on the CNC router. 


This time I had a new thing to deal with: thin bits of wood (anything under 7 or 8mm in my experience) will have a tendency to warp naturally, and so it was with the wenge fretboard I'd thicknessed just a couple of days earlier. Whilst I kept it pressed under one of the body blanks, that didn't help combat it's desire to want to be curved along its length. Normally I'd have made the fret slots before gluing the board to the neck, but given it wasn't straight I couldn't do that, as the curvature would be enough to throw of the slot positions that I etch with the laser cutter, as that process assumes a perfectly flat bit of wood.

So instead I just re-ordered things. I glued the fretboard onto the neck without the fret slots, following the technique I used last time, but without the salt, and it worked fine. The reason for trying the salt was that it would stop the fretboard and neck slipping out of position as I clamped them down, but I just used some small spring clamps (like those spring clip clothes pegs, but a little bigger) to hold the two pieces in place whilst I did proper clamps, and that was enough to ensure a good alignment.


Thankfully this time the seam between the two pieces was nice an tight. I'm still not sure the salt was to blame vs defects in the finishing last time, but either way, it's clearly not needed for what I'm doing, and saves me having to try expense salt as a building material I guess. I was then able to put the entire neck into the laser cutter to do the fret slot etching, and had a nice calm hour or two whilst I cut them to the final depth by hand with a saw.


After that, side inlays went in, and for the top inlays rather than use plastic pearl style dots I'm going to try vintage style clay dots, which hopefully I can report back on next week. Once the dots are in I can then carve the neck profile (again by hand) and radius the fretboard.

I wanted to start cutting the bodies this week, but I had a nagging paranoia about spacing of the control cavity on the Offset body, so I set about to remove my paranoia. Most of the time when something goes wrong, it's usually because I measured and cut, rather than measured, measured, and then cut. I really can't emphasise that enough to anyone thinking about building guitars, or indeed anything physical. It sounds glib, but it really is the most common cause of mistakes, so if you have a nagging voice in year head worrying about something to do with measuring, it's always worth paying attention.

If we look at an earlier picture of the Offset design I'm making:

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You'll note that the seam between the pick-guard and the control plate isn't very neat. To be fair, it's also not very neat one some of the older Mustang's I've looked at, but we should be doing better than that. It's important to get this right not just for visual appearance though, the joint there will define the angle at which the control plate sits, which will define whether it actually sits neatly over the cavity underneath the control plate where all the controls are wired; if you get this wrong there's a risk that you'll see a slight gap at the edge of the plate, which would be unacceptable.

To solve this, I needed to do get a better model of the control plate itself. I'm making my own pick-guards, so I can make the seam on that side however I like, but the control plates I've bought in, and so I have to make sure what I create matches with them. Unlike say a Telecaster control plate, which just has a semicircle profile for the point where it meshes with the pick-guard, the Mustang control plates have a flowing set of curves for the same point; this is pretty, but as a designer trying to model one it is quite annoying, as nowhere is it written down how those curves are defined.

My first attempt to model them was to just measure the heck out of the control plate as much as I could with some calipers. There's no straight edges on this thing at all, so it's really quite hard to measure manually, but I gave it my best shot. I then fed all those measurements into Fusion 360 and tried to see if I could get something that was close. 

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You can see this is a bit of a mess, and got much worse as I added more detail, and despite that it just wasn't accurate enough. Because I need to manage lots of relationships here you end up with compound errors, so whilst the bits at the top weren't too badly positioned, by the bottom you're quite a bit out.

An alternative approach was suggested by my friend Jason, who I got hooked on Fusion a little while ago for his electronics projects. He suggested I put the control plate into a scanner to get a good picture of it, and then in combination with the measurements I had, that'd be enough to get an accurate model of the plate. And indeed, it worked a charm. The measurements I'd made let me scale the scanned image to the right size, and then I could use the scanned image to make sure all the holes and curves aligned. The result was a bang on model of a Mustang control plate.

Having got that bit down, I then went back to the pick guard design I had basically just remade the bottom half from beginning again. But this time everything meshes together much more nicely, and I have confidence that the control cavity is in the right place relative to the control plate. 

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I also verified this by printing everything I need to make out to scale on paper, cutting them out, and making sure they meshed with the physical parts I have to hand; it was all very Blue Peter, but a great way to gain confidence that things will work with the real parts, not just in your computer model of them.

The end result is I have much more confidence in the design now, and am happy to start cutting the bodies this week.

One of the reasons I got into guitar building is I enjoy learning, and this week I got to learn something else new that hopefully will come in handy: I got trained on the metal lathe at Makespace, and I made this plumb bob as part of my training.


Whilst I won't be using this on the current crop of guitars, it does give me ideas for how I might be able to fabricate parts for future things.

A week in and out the shop

Not much shop time this last week, due in part to the ongoing CNC router issues, and in part due to having a wisdom tooth extracted, which knocked me for six for a good few days, causing me to hide away doing other things whilst I recovered. But I did manage some progress, so here's a very quick run through.

I gave my talk on how to get started in a new discipline to CamCreatives this week, which was a lot of fun. I took along a couple of guitars and my amp and talked about the methods I used to getting started in a practice I knew nothing about, and how I kept myself going during the hard times when it all seemed to be going wrong: hopefully all lessons others can apply to things they'd like to try doing but have been putting off as they didn't think they could do it. 


As with all these kind of events for me the big kick is afterwards, talking to individuals about how guitars are made and then seeing people with more musical talent than me elicit nice music from things I've made. Thanks to Paul and Steve of CamCreatives for organising it (and for the above picture), and to everyone who came along!

Prep for this reminded me that I've not done anything like this for a while, and I do enjoy doing little bits of talking like this, so I'm looking for other opportunities to talk about this stuff: if you know of any, give me a shout. The call for talks for EMFCamp is open, so I submitted this one there, as it seems a reasonable alignment with the theme of learning new things you can try that pervades EMFCamp.

Most of this week though has been dominated by the saga with the issues around the CNC router at Makespace (see last week if you missed the write up of its misbehaving), though with some progress in the last couple of days. The owners have been trying to find a way to trigger the failure so we can understand how to then fix it, but without luck so far. I spent a few hours doing more test runs myself to see if I could get it to fail again, and used this as an excuse to do another trial run of the offset body in foam, this time doing both front and back of the left hand half (which is more interesting, as it has the comfort cuts on both sides). Whilst I didn't manage to reproduce the failures, I did learn that I'm happy with the design, so ready for a wood cut version next.


In the CNC pass I don't do any routing off, just the general cuts, so you can see a few sharp transitions in the foam model that'll be removed by hand, likewise the edges will be given a smooth radius too by hand.

The current top theory on the CNC router is it was just a glitch, possibly due to electrical noise with other kit, so I decided that having been unable to reproduce the failure thus far, I'd go in when the space was quiet and do some actual cuts on wood. Whilst I still fear the machine going rouge, at the same time I need to try make some progress, and I have yet to complete my prototype neck build, and given that's relatively inexpensive wood wise I started with that. Thankfully it passed without issue, though I was hovering over the stop button on the router the entire time (which is about an hour for those interested) as I don't want to fork out another £40 for yet another router bit.

So, whilst I still don't trust the machine and the Makespace community is still chasing the answer, I've managed to make some forward progress again at last. In the coming days I'll cut the fret slots and then glue it together, hopefully with better results than the previous attempt with the salt (if this has you scratching your head, read last week's notes :). 

Of course, this also skims over the fact I had to order yet more wood since the last bit was destroyed and yet again use my friend's workshop to thickness the wood correctly. Given how much this incident has slowed me down and how much I still don't trust the CNC router I also ordered the wood for a spare body blank which I've also thicknessed, jointed, and glued. 


The fine folk at Exotic Hardwoods must be loving my recent purchase patterns, but I'd rather have some ability to cope with the unexpected right now. I often get asked about the pricing for guitars, and events like this are part of why a single hand built guitar has to be priced high. If you have one failure like this in a thousand guitars, then the overhead isn't that much, but if you have one failure even in half a dozen guitars like this it can really knock your pricing if you've not allowed for it. The cost of a guitar isn't just the materials, and isn't just the time it takes you to make them, isn't just the tools and rental fees: for a business to be sustainable all these random unpredictable failures need to be allowed for to some degree.

Random shiny things of the week: the pickups I ordered for guitars #5 and #6 have arrived from the ever awesome House of Tone Pickups, looking splendid as always:


Alas I have nothing to house them in just now, but at least I can double check measurements on them for the bodies.

Between being blocked by the CNC router failure and having bits of my head ripped out, all in all this hasn't been the best of weeks. I'm hoping though that forward progress will pick up pace again now.

A frustrating week in the shop

This week was mostly in the shop, which is always nice, but has been a week of mostly setbacks unfortunately; but that's just how it goes some times. So let's battle through the frustrations together in this week's catchup.

First let's start with a nice thing that did work out. Last week I shared how I needed a shooting board for doing the straight edges when bookmatching wood for the tops of guitars. I knocked up a shooting board in Fusion 360 last week:

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This week I cut the parts out on the CNC router from bits of scrap MDF and ply I found in the workshop, and now Makespace has a nice new shooting board I can use:


It's quite nice being familiar enough now with Fusion that I can just quickly knock something out like this without much thought. A long time ago a friend gave me the advice in writing software you should pick one text editor and use it for everything, both big and small jobs, so you become a master at your most important tool. Fusion is certainly becoming that way for me. I spotted the workshop scroll saw was missing a simple part (the occasional downside of community workshops), but I quickly modelled up a replacement in Fusion and printed it out on one of the Ultimaker 3D printers we have, and by the end of the day had everything back as it should. That ability to go from idea to implementation like that is a wonderful thing.

It's also nice to share. So firstly, if you're at all interested, you can grab the design for the shooting board here. Secondly, if you happen to be a member of Makespace, I'm going to run an workshop on how I use Fusion 360 to target the various bits of kit in the space. I don't claim to be an expert, but I have produced enough things that I have enough bits of knowledge I can share to help others get started, and then hopefully they'll make cool things I can learn from too.

Last week I talked a lot about how I was building the next batch of guitar necks compared to how I did it previously, and what might go wrong with the new approach. Unfortunately, I started the week with a failure gluing the fretboard onto the neck, though not the kind of failure I'd anticipated with alignment in last week's post. When I clamped down the fretboard for gluing I couldn't get a perfect join between the main part of the neck and the fretboard, leaving an untidy finish along the side of the neck, and because the parts are already the correct size I can't do much to sand it out without taking too much material away.


There's several possible explanations for why I have these unwanted gaps, and I now need to repeat the experiment to work out why. Firstly, I was trying something I'd not tried before as recommended by another luthier to help stop the wood slipping before the glue sets, and I sprinkled a little salt into the glue. The theory here is that the grit of the salt will add friction between the two sides to stop them slipping as you clamp. Certainly following the approach did work in the intended way: between the glue and using temporary clips as I clamped the neck everything remained wonderfully square. However, it could be the salt I used wasn't ground fine enough and is responsible for the neck and fretboard not joining seamlessly, being high enough crystals still to cause some gaps. I actually think using the clips to hold the board as I clamp it was probably enough to stop unwanted movement whilst clamping anyway, so I'll probably do as the chap in the video does next time but without the salt.

The other possibility is that I didn't get the wood flat enough before joining. I used a 1 inch router bit on the CNC router to thickness the wood, but that leaves some ridges in because the router isn't 100% true, so you have to sand it a little after. It could be that after sanding I'd been a bit too agressive in parts and left the wood not perfectly true. But I did hold the wood together before gluing and it looked okay then, and all the previous necks I've made I used this technique and they came out okay.

Either way the end result is I now needed to make another prototype neck. This one isn't a total loss though: other than the seam between the fretboard and the neck body not being perfect, it lined up fine and is sturdy. So at some point I shall use this as an experimental neck to try applying fretboard binding on, which will hide the bad glue line. I'm fairly sure this is in part why binding became a thing for guitars, in addition to hiding transitions between nice expensive cap wood and cheaper body wood.

On Tuesday, in part a reaction to my neck joint failure, and in part because thicknessing on the CNC machine in Makespace is so very slow, I took up a very kind offer from another Cambridge luthier to let me use his thicknessing machine to level out the next batch of wood stock I had waiting to go: the swamp ash body for guitar #6, another prototype bit of maple to replace the prior neck, and a couple more wenge fingerboards.

I'd never used a thicknesser before, so it was a fun learning experience. It's basically a machine with a feedbelt into which you insert you wood and it just planes a sliver off the surface each time (as you would with a hand plane, but it has a much wider blade so can cope with wood up to 30cm wide). In the time it takes me to thickness one side of a guitar body on the CNC router at Makespace I'd done all stock I taken to run through the thicknesser! It made quite an impressive pile of dust too.


That still took over an hour, and is surprisingly physical work given the machine is doing the hard bit. But such a time saver. I'm now campaigning hard to get Makespace to speed up its plans on getting such a tool!

As a new luthier you won't always have the right tools for the job, and doing something with what tools you have (in my case a CNC router or a hand plane) is much better than doing nothing. But as you scale up, knowing which tools to get in which order is a good thing. My luthier friend said a proper thicknesser was one of the first things he got as he was scaling up, and you can see why given how much time it saves.

Tuesday afternoon I spent in the practice studio at Rhinocorn Studios, recording some demo footage for the amp.


I'm really pleased with the amp, having at long last being able to forget about building it and just play it. It has a wonderful clean sound at low volume, but as you crank it up it distorts nicely. It's not perfect: if you crank it too much it starts to get a bit flabby with its distortion, which I put down to using a 10" rather than 12" speaker. But this issue is only at volumes I wouldn't normally use when practicing anyway, so for now it's okay, and if I do find that an issue I designed the case to be large enough to house as 12" speaker should I want to upgrade in the future.

Tone wise it suits the kind of music I play down to the ground. The session was also an excuse to play with my new Keeley D&M Drive pedal, which I'll write up a review of at some point, but also worked really well in this context, particularly the boost side of the pedal, which I just love.

Anyway, the footage is all shot, but because I'm behind where I want to be in terms of guitar building right now, I'm not going to edit this video myself. In any startup endeavour, there is always more to do than there are hours in the day, and whilst the temptation is to do everything yourself (particular as a lot of it is interesting/fun), where possible you should focus on the core of what it is you're trying to achieve and delegate/outsource the rest. In this instance, although I enjoyed editing the last two demo videos, they took a long time to producew, and I'd rather be building guitars right now (particularly given the setbacks this week). So I've passed editing responsibility over to my brother Tristan, who in addition to being ace guitarist runs his own video production company that specialises in music and tour videos. He now has the delightful task of going through two hours of video and six hours of audio trying to make it sound like I know how to review an amplifier :)

Wednesday I made it back into the shop, where I glued up the swamp ash body using my newly ordered sash clamps. Previously I've been using strap based clamps that Makespace had for clamping large things like guitar bodies, which get the job done but are a bit of a faff. But watching the video last week on gluing bookmatched caps, I discovered the existence of sash clamps, which also are much easier to use for gluing bodies. If you need to joint bodies or caps I highly recommend you get some, and they're not that expensive, so definitely a worthwhile investment.

This means that the bodies for guitars #5 and #6 are jointed and ready to be cut into actual guitars. However, before I ran my new offset body design on the wood, I found some foam on which to do a test run. Even cheap guitar body blanks cost me £40ish once you factor in postage etc., and good wood blanks cost even more, so I wanted to find a cheaper way to validate my designs before cutting wood. Thankfully, I found a fellow Makespace member who had some insulation foam they wanted rid of, so in exchange for some beers I got myself some nice test material.


I'm really pleased with how the body shape has come out, the roll off of the arm cutaway is just as I hoped, but it's much nicer to see if in reality versus on screen. However, this is where my week really took a turn for the worse. You can see above in the cutaway there's a pair of marks where you'd not expect them: at the time I put this down to some foil from the top of the foam getting caught on the bit (as it has a tendency to do) and artificially extending it briefly, so cutting more than wanted briefly. But in fact this was an indicator things were not well with the CNC machine.

Having done the body, I went onto cutting another neck prototype, something that should have been a trivial job given I'd only just cut the previous one at the end of the last week. After about an hour of carving the neck on the CNC router (doing the headstock details and the headstock/fretboard transition is slow work if you want a good finish), the router was on the final pass to cut the neck outline, separating it out from the rest of the stock, when there was a bang and the entire thing popped off the CNC router. On inspection the CNC router had decided that rather than just trace the outline of the neck on a single level as it was meant too, it wanted to also descend the cutting bit too, at a much higher rate than anything could cope with. This cause a catastrophic failure: the router bit shattered, taking with it a chunk of the neck wood.


I was a bit too flustered at the time to take proper pictures, but the damage to the wood is much worse on the rear: this neck is now scrap, and I'm down a router bit. I effectively lost £50 in parts here between the router bit and the wasted maple. I'm just thankful it wasn't one of the body blanks I was routing at the time, as that'd have been easily £100 down the drain. In hindsight I should have seen the defect on the foam cut as being more worthy of note than I did, but the CNC router has hither too been nothing but reliable, so I had no reason to suspect anything like this would happen.

So, what went wrong? At this point I still don't know and getting to the bottom of this is my top priority right now, as guitars #5 and #6 are blocked on getting the CNC router back in action. There's a long thread on the Makespace mailing list as we try to diagnose it, and I've done a number of tests myself just running my designs on air or foam, and I've yet to be able to reproduce the failures again. But I'm no leaving an expensive (and potentially physically dangerous) failure like this down to chance, so investigation will continue on Monday once I get back from my weekend trip to Liverpool.

One thing we did manage to rule out was whether I'd messed up the design export from Fusion; Occum's Razor after all implies that as still a relatively new person to wood working (just two years :) it would be myself that had done something wrong rather than the machine. I use Fusion 360 to generate the commands that drive the CNC router, but because each router machine is different, you have to be quite careful on the settings used when exporting. I went back to Fusion and checked the toolpath I thought I'd generated, and as you can see here all looks well:

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So next I needed to validate that the command file exported from Fusion 360 that I fed to the router also made sense. I discovered a nice website call NCViewer, which lets me load the command files Fusion generates for the CNC router, and in both cases it let me see that the command files made sense:

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This, along with a review of the machine settings leaves us pretty convinced that it's nothing I've done wrong on the input side, and that there's an intermittent fault with the machine itself somewhere. On Monday I'll start by checking all the wires and cabling and trying to get that moving forward again.

Waiting for advice on the CNC machine from people more educated on it than me left me with some time do swap out the old resins on the FormOne 3D printer we have for newer resin stock, as we'd been having a lot of failed prints, and we put this down to the resin having expired. To test this I did something I'd wanted to try for a while, which is printing my own control knobs for guitars. The fiddly bit here is ensuring they fit nicely on the potentiometers used for the volume and tone controls.

So I knocked up a quick design in Fusion with what seemed a suitable interface for mounting on the pots I use, and got that ready for printing:

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And then printed that out:


And much to my delight it fits pretty well:


Which was a nice end to an otherwise frustrating week. Not sure these are a design I'd use, but it's a nice example of rapid prototyping in action.

Before I finish up, just a quick reminder that I'm talking about the highs and lows of guitar building on Wed March 28th in Cambridge at CamCreatives. Do come along if you want to learn more about how I got started on this, and see/hear the guitars in action!

A week in the shop

At the end of last week I'd CNC'd out the neck for my offset design, and this week I made the fretboard to go with it. For the current builds I'm trying a new approach to making the necks, in part due to how I want to deal with the headstock to fretboard transition as explained last week. This will hopefully give me nicer results and reduce the risk of mistakes overall, but forced me to try some new approaches.


In previous builds, when adding the fretboard to the neck, I glue the fretboard to the neck before I shape it. I marked where the frets are going to be on the board with the laser cutter (as explained here), pencil in the line for the 0th and 12th frets on the the back of the board, and then glue the board on matching it to similar pencil lines for the 0th and 12th frets I've made on the neck itself. Once the glue is set I just run around the neck using a hand router with a following bit to make the fretboard flush to the rest of the neck (alas, I just checked my photo album and I don't have any pics of this bit in progress, sorry).

For the offsets I wanted to try a different approach, whereby I do as much of the fretboard as possible before gluing it to the neck, in part to minimise the risk of wastage if I make a mistake on the fretboard, but also it lets me do a similar trick I did last week on the neck to get the headstock/fretboard transition just right using the CNC router. So my new approach to the entire thing is thus: thickness your fretboard materian (in this case a nice bit of wenge), do the top down outline of the fretboard on the CNC router, along with the headstock transition, laser etch the fret slot guides, saw the fret slots, glue fretboard onto neck.

There's a bunch of places where this can go wrong. Any time you have to do operations that require alignment on different machines you always have the risk of misalignment when you try to join them up; ideally you'd do everything in one pass on a single machine, but that's obviously not practical. In the original workflow I had this was only at one point, where I had to line up the fret guides I'd made on the fretboard with the pencil marks on the necks. But even then I've made the problem simple as I don't mind if I get the fretboard a little to one side or the other as it's only on one axis I need to be matched. In my new workflow I now have two points where I need to align things: firstly when I add the guides to the already shaped fretboard and then secondly when I glue the fretboard to the neck.

To solve the first one, I came up with a plan whereby I stuck down paper to the laser cutter bed (sticking it means it won't move during subsequent stages), scored the outline of the sides of the fretboard, placed the fretboard carefully over that, and then (after remembering to adjust the laser focus to allow for the fact the fretboard surface is 6mm higher than the paper) etched the fret slot guides. This actually worked quite well, here you can see the paper outline:


Then here's the etching in progress:

And here's the end result:


You may note from the video that I actually ran the etching pass on the paper before I did it on the fretboard: this was a lack of faith that in switching between the outline program and the slot guide program on the cutter it had reset the original correctly. It turned out all was well, but as ever: measure, measure, cut.

Once the guides were etched I then was able to sit down for a quiet hour or so with Live At The Regal on in the workshop and saw each fret slot to the correct depth.


Now I'm ready to glue the slotted fretboard to the neck. This is the second risk point I mentioned above: I have to ensure that when gluing these two together they line up perfectly, and stay lined up. One thing you learn quickly when clamping wood for gluing is that it causes the two parts to move. I've done some research on how to prevent this, and I'll report back next week if that's successful.

As part of doing the fret slots I finally got around to updating my fret board generation software, which is open source and you can read more about it here. When I first mentioned it here I had an issue with the otherwise perfect Maker.js library, whereby it wouldn't omit polylines, just individual lines, so I had to have an extra post processing stage on any freboard I generated to turn the slot rectangles into actual rectangles in the eyes of the laser cutter software. Dan Marshall kindly fixed that issue in Maker.js, so now I can just generate my fretboard designs and run them on the laser cutter effortlessly. Thanks Dan!

Other progress on the offsets was a little less visually exciting, but I sat down and worked out the tool paths for the CNC machine to rough out the body. This is reasonably complicated due to the fact I need to CNC from both sides of the material. The trick to doing this is you route out some holes in both the material and the CNC bed to put in metal dowels that let you line the body up perfectly up for the second side (this is called the pin alignment technique). You can see the dowel holes in the picture below in the corners.

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Thankfully it turns out you can get Fusion to generate tool paths for both sides of a model, so at some point this week I'll give that a go on some foam, and if I'm happy with that I'll route out the body in the wood I jointed last week.

One of the offsets I'm making is a thinline version; for those less familiar with Fender terminiology, that means it's semi-hollow, with a solid centre block, but cavities in the body to either side. This is achieved by making the body out of two pieces: the main body block, and a cap bit of wood to make the lid. In the picture below I've made the two parts different colours to help get the idea across (don't worry person who ordered guitar #6, it won't look like this in the end ;)

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I say two pieces, but technically it'll be four as the body will be two jointed bits of swamp ash, and the cap will be two jointed bits of 5mm thick maple. I've never built a capped guitar before, so I've been reading up on that to work out what the fiddly bits are. Firstly, I wanted to know how to joint something as thin as a cap, as the usual tools I have at Makespace didn't seem ideal for that. After watching some videos (including this really good one by Crimson Guitars) I'm now better educated. Firstly, I'll need a Shooting Board, which is a fancy name for a jig that'll let me run my jointing plane along the edge of thin bits of wood. Makespace doesn't have one of these yet, so I'll be making one in MDF in the coming days.

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Also, I'll need some better clamps than the chord clamps I currently use, called sash clamps, which will actually make jointing bodies easier I suspect, so they're on order.

In addition, I was looking at how you can wrap the cap over the arm comfort carve. In the picture above you can see I've been lazy and just not put the cap over the comfort carve area at the bottom left of the guitar. In practice I want to bend the cap over that area so you don't get two different wood styles on the top surface. After watching yet more videos on youtube (YouTube's 2x playback is very much like Neo's "I know kung-fu" moment), I can see how to do this by making some small channels on the back of the cap where it has to curve to make it more flexible. You'll get to see in the coming weeks how that goes.

In addition to building guitars I got to show them off this week. Thursday was an open evening at Makespace as part of the Cambridge Science Festival, and then Friday evening was the Makespace 5th birthday party. It was great to see lots of people interested in the guitars and amp, and I got to spend a good chunk of the two evenings providing background blues guitar music when not showing the guitars off. It was also wonderful to see people play the demo guitars: I get a real kick out of seeing people elicit wonderful tones out of the things I built in ways I never can. Thanks to everyone who stopped by and let loose some licks.


However, in the practice of sharing my mistakes as well as my successes in these posts, the evening wasn't without incident: unfortunately at one point the strap on one of the demo guitars came loose when someone was playing it and the guitar plunged to the floor. Thankfully the person was quick enough to sort of catch it enough that it didn't hit the ground hard (in fact, it landed on their foot), and in the end there were just a couple of scratches to the surface that have polished out, but boy was I kicking myself for the rest of that evening, which soured an otherwise wonderful event.

Whilst I feel very precious about all the guitars I build, I have to put them in other people's hands to let them see what I can do if I want people to pay me to build them guitars, and thus I have to accept the risk that accidents will happen. The question then is, how then can I reduce that risk in future? Firstly, I've ordered some rubber strap locks. I've never used these as I've never had a strap failure like this before, but clearly it can happen, so I'll try and reduce that as much as I can. Secondly, I'll have a bar stool for people to play on, so they're sitting down rather than stood up. Again, the fact I didn't is down to the fact that I stand to when playing, even when at home practicing, but clearly a sat down person is less likely to drop a guitar than a stood up person.

Anyway, hopefully you can learn from my mistakes without having to go through the heartache I did on Friday: I had to put on a brave face for the rest of the evening, but for most of the remainder of that evening I really just wanted to go home and make sure the guitar really was okay. If you have any other tips for avoiding this kind of incident do let me know!

A week in the shop

Thanks to the snow thawing out, bits for guitars #5 and #6 started arriving: the wood and the basic hardware that will attach to it (the bridges, tuners, etc.). So this week has been mostly about getting those guitar builds moving.

First up, the selection of wood arrived from Exotic Hardwoods UK Ltd. With guitars #3 and #4 I went to a local lumber yard for the body and neck woods, and got the fingerboards from random other places on the Internet to suit the build. This time I went to Exotic instead for everything, and someone was asking why not continue to use the local lumberyard as that must be cheaper.


Firstly, whilst the local lumberyard has some nice basic ash and maple, but it's actually a pain to get to the workshop. The lumber yard is about 20 miles away from Makespace, and they don't have the facilities to cut it for me into rough bits that will fit in my car, so I'm in the lap of the gods a little when I go in terms of can I get bits I can transport: we only have a small car, so I can't fit a plank longer than 2.3m in the car, and most their lumber is longer. Indeed, the last time I went I came home empty handed as the shortest plank they had was 2.5m. So whilst buying pre-cut sections of ash is more expensive, it's way more practical even if it does close to double the price.

Another reason is the selection of woods: the kind of Ash I can buy at the local lumber yard is standard American Ash and this can be quite weighty. Whilst some people like that, indeed that was part of the specification for guitar #5, some people don't, and for guitar #6 the customer wanted a lighter guitar. For this I've gone for the more expensive Swamp Ash, which is notably lighter than American Ash, but also not the kind of thing that you get in the run of the mill lumber yard in the UK that's supplying mostly builders. Thus going to somewhere like Exotic made sense, and a fellow luthier I know has been very happy with the Swamp Ash they get from Exotic.

Similarly for the necks, although the maple I got from the local lumberyard was perfectly fine for regular necks and quite cheap (a fiver a neck for the raw material!), it's the same problem transport wise, and for both guitars #5 and #6 both customers wanted something premium maple wise, so we've gone with some birds eye maple which has lovely figuring in it, and really for that you do need to go to a specialist wood supplier.

With the wood acquired, it's time to start making parts for the guitar. Guitars #5 and #6 represent an important step for me as a luthier: for the first time I'm using my own drawings rather than using existing templates. So although the guitars are based on an existing guitar design (the Fender Mustang), I measured and drew the designs myself in Fusion 360.


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Moving to Fusion 360 is quite a change workflow wise. Until now I was feeding 2D drawings into the CNC router software we have at Makespace which supported just basic 2D operations such as outline, pocket, and drill. Fusion 360 gives you much more flexibility, but requires a different way of thinking about things. So, before I let loose on the lovely birds eye maple, I took an existing maple neck blank I had and set out to carve a neck from my new designs. The more astute regular readers may note that I'm now making prototypes for the prototype guitars :) 

The neck design I've gone with here is different from what I've done in the past for my teles. Partly, this is due to practical reasons: Mustang's have a shorter 24" scale length compared to the 25.5" scale length on a tele or strat, which means a shorter neck, which means a standard truss rod won't fit in in exactly the same manner. At the same time, I was never happy with the truss rod access on the tele's I've made (or indeed owned), both in terms of it being fiddly to get right in construction, and it's fiddly to use. I much prefer the access offered on some other guitar makers I've seen, such as those of Fidelity Guitars and Titan Guitars. So using those designs as inspiration, these necks will have the truss rod end exposed for easy access and adjustment, so it's more functional, and it simplifies the construction a little to let me build the necks more accurately.

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One of the other things I wasn't happy about with the previous necks was how I made the curved transition between the headstock and the fretboard. Ideally you'd use a drum sander to get the radius there, with a jig to limit how you can move the neck ensure you don't take too much away. Makespace doesn't have a drum sander unfortunately, so I'd been using a drum sanding drill bit fitted to the pillar drill as a work around. This got the job done, but was hard to use with a jig due to the plate on a pillar drill not being as big as on a drum sander, and I ended up having to spend a bunch of time trying to correct the end result until I was happy with it. This time around (as I previewed the other week) my plan has been to carve the transition on the CNC router. Because Fusion 360 is a 3D CAD and CAM tool, I can actually get Fusion to generate 3D tool paths for the CNC router, and so this seemed like a sensible place to take advantage of that.

You obviously get into the is it hand made if you CNC route it debate here, but ultimately whilst I'd love to do this by hand, I just don't have the right tools right now, and it's way more important to me that customers get a guitar they're happy with than did I hand shape every single last bit of it. One day I'll have a drum sander, but for now, this is the best way to make something I'm happy shipping to someone.

Thus this week I sat down for a good few hours to nurse the CNC router as I made my first neck from my new design:


With any new CNC router plan, you really do need to sit and watch it do every cut, as you don't know what the software will make of your design. Indeed, during this cut I had to stop it several times and go back and tweak my approach to the routing as I learned more about how Fusion likes to do things. But in the end, we got there.

I'm really pleased how it came out. The headstock design is my own that I'll use for all Electric Flapjack guitars that have tuners on one side, and I think that's come out good: it's not too flashy, but also different from what a traditional guitar of this type would have so you know it's a custom guitar rather than an original. The headstock transition has come out great; after the experiment the other week I got a ball end mill to do just this bit rather than using the same end mill I use for the rest of the carve, and that curve is wonderfully smooth as a result. I can definitely recommend investing in a ball end mill if you need to do curved surfaces when routing.

Next week I'll make a fretboard for this, and if that goes well I can make the actual necks for guitars #5 and #6 after that.


I also spent some time jointing the guitar body blank for #5. Whilst you do get guitar bodies made from a single piece of wood, it's more common that they'll be made of multiple pieces just due to the practicalities of getting a reliable source of wood big enough and at a reasonable price. So as with guitars #3 and #4, guitars #5 and #6 will have two piece bodies. To ensure the parts glue together well, you need to make the edges as level as you can, and for that I break out my #7 jointing plane (#7 refers to the size). It's a labour intensive few hours, and boy did I feel it the next day, but the parts had a lovely close finish and is ready for getting to the right thickness and routing.



Closure on the amp construction: it is now fully finished! Last week I'd got it all working except the neon power indicator still wasn't working, even though I'd bought a replacement bulb. During the week a third bulb turned up from a different supplier, and that worked!



My assumption now is that the original supplier unfortunately had a duff batch. I've let them know; less that I'm worried about a refund for a component that costs less than a pound, but more so that they can check the rest of their supplies before shipping them to others. It could still be me of course, perhaps I accidentally overheated the old bulbs whilst soldering them, but for now all I really care about is the amp is finished and I can shortly take it home and make it my daily amp.

The reason I'm not taking it immediately home is because I'd have to bring it straight back to Makespace in a couple of days for the show and tell events, where I'll be exhibiting a couple of my guitars and the amp, and explaining how I used the various bits of kit at Makespace to build them. One of the days is a Makespace members only party to celebrate Makespace's 5th birthday, but on Thursday 15th there's a public open night at Makespace as part of the Cambridge Science Festival, so if you want to see me in my workshop environment, do come along to that.


But that's not all!

On March 21st I'll be giving a talk at the CamCreatives meet up about how I got started in making guitars from having no experience, a bit about what's involved, and generally trying to encourage people that stepping into a totally new field is very doable if you just approach it right. The meetup invite for that should be up shortly, and I'll post here when it does.

I'm also very excited to announce I'll be part of Liverpool MakeFest again this year, which will be on June 30th at Liverpool Central Library. I'll have a stand showing off some guitars and bits of in-progress guitar and trying to explain to people how they too can make things. I did this last year, and it was a wonderful day talking to people about building things, and trying to encourage people that whilst making things may seem daunting, but again really isn't if you just start small and work your way up.

I still find it amazing that two years ago I'd never made a guitar, and I hand't done woodwork in over 25 years since high school. I get a kick out of trying to show people who see my guitars and think "I could never do something like that" (be it guitars or whatever their passion is) that it's just taking the right approach to starting something new that they too can do this sort of thing. So if you have a meetup for such you'd like me to do such a talk, do let me know!

Come see and hear our guitars!

Occasionally people ask if they can see the guitars and amp, and perhaps see where I build things. Well, now's your chance! Makespace, the community workshop where I build everything, is celebrating its 5th birthday this year, and will be having a show and tell for two consecutive nights: the first one, on Thursday 15th of March, is open to the public as part of the Cambridge Science Festival, and the second one on Friday 16th is a Makespace member's only party in the space, where I'll also be doing demos and perhaps having a bit of a jam if I drink too much soda.

 Me doing some demos at the last Makespace show and tell night in early 2017

Me doing some demos at the last Makespace show and tell night in early 2017

So, if you're in Cambridge next week and want to see what myself and others have been building in Makespace all these years, then drop by on Thursday 15th, or of you're a Makespace member come and join the party on the 16th! If you can't make that then don't worry, I have a few more events planned in the coming months, which I'll post here once they're properly announced.

A week out the shop

Not much shop action this week. I did go back into the shop to try fix the last bits of the amp left over from last week. I got everything fixed up except the neon power indicator light isn't firing properly. I replaced it with a spare and same result, so either I've messed up or the pair I bought happen to be from a bad batch of indicators (though Occum's Razor would imply the former rather than the latter :). Still, didn't stop me annoying people in Makespace by firing it up and having a bit of a jam.

You can see the tubes are glowing nicely on the back:


Even though it's just a 5 watt amp, it is loud! I didn't crank it in Makespace out of respect to other using the workshop there, but at bedroom type levels it has a lovely clean sound with just a hint of break up. I look forward to dragging it into a practice studio in the very near future and opening it up properly.

A couple of people have enquired if I'm going to build amps for people alongside my guitars. The answer there is a strong maybe, but I'll have to gauge interest first. There's a couple of reasons amps are harder to build than guitars, and it's nothing to do with the actual construction part. Indeed, I've taken care with my amp design on the CAD side so that I can very quickly come up with new amp layouts (e.g., a 2x12 vs a 1x10, more controls, etc.) just by adjusting parameters in Fusion.

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The first issue is, due to the very high voltages involved with a valve amp, I'd have to go through certification before I could sell them, which I'd have to do for each model I made. This makes it hard to do fully bespoke amps each time, but I could do a small set of designs with some minor variations (e.g., similar circuit but head vs combo would be counted as one design). But the basic point is I can't just build them and flog them, I'd need to invest both time and money in the certification process, and at the moment I'm not sure I offer much over any others building custom amps. The second is the cost for me of building amps to a specification that makes me proud of them vs what the going rate seems to be for a small practice/first gigging amp makes me think very few people would pay say a grand for a 5W amp, even if it was lovingly hand made out of top quality bits.

But, if you'd like to add your voice to those asking if I'm going to make them so that I can work out if its worth the investment in certification, let me know. For now I'm going to settle for this, and perhaps later in the year build a 15W gigging amp based of a Fender Deluxe type circuit. But for now, I have some guitars to build...

The prototype guitar offer I made a few weeks ago has now properly closed, with deposits in, and two guitars locked in to be made (it did look like three, but alas one got away for now). I started ordering bits, most importantly the wood so I can get started on these. The wood for these is coming from Exotic Hardwoods UK Ltd, who have a wonderful range of materials for guitar building. Once these are in I can get gluing and machining the wood into rough shape. I was hoping the wood would have arrived, but the disruption caused by the snow has stopped deliveries getting through as quickly.

Both the prototypes in the end are for offset guitars rather than teles, which is not what I set out to do, but I'm quite excited about this. Both will be based on a Fender Mustang, which is a short scale length guitar, and one of the cheaper guitars that Fender offers, which means if you want a nice high quality Mustang you need to go custom. From a builder's PoV they're sufficiently close to a t-style guitar that what I wanted to achieve from the prototype series in terms of workflow still holds. So I get to make something unique for both customers. Here's an early prototype rendering of one of the guitars, which will be a thinline model:

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That's about it for this week, as I've mostly been waiting for bits and doing non-guitar contract work, but looking forward to being back in the shop in the coming weeks!

A week in the shop, in spreadsheets, and in Birmingham

We'll start with the bit I suspect any regular readers will be wondering: did the amp get any closer to being finished? Well, yes, it did: in fact, if it wasn't for a couple of dodgy components, then it'd actually be fully completed.


Last week I'd managed to make the turret board ready for assembly, so this week I started by soldering that up first, adding the components on the front and all the connection wires on the back, a task made much easier by the loan of a 100W soldering iron (thanks Rob!). 


Then I spent a morning cutting wires to length, tinning them, and connecting the board to the chassis and non-turret board components (input and output jacks, volume/tone pots, valve holders, and transformers), and I also wired up the rest of the power side. As someone not practiced at this it took me the better part of 5 hours to get everything attached and in place; this was in part due to lack of soldering practice, but also due to being paranoid and regularly double checking things against my hand drawn schematic and the original reference circuits I'd found online.

Much to the amusement of some of the more experienced analog engineers I know (who kindly helped out with final testing) I used a lot of terminal blocks to connect the transformers up rather than soldering them on directly. This is the software engineer in me I suspect: although it's left me with a rats nest of wires, the idea is that the expensive components will not be committed (by shortening their leads and soldering them directly) until I know my design works. It's much easier to shorten the wires once I know I have everything right than it is to extend the cables if I've got anything wrong.


Then came testing time. I found some good guides on how to do initial power up testing on an amp (here and here - although I didn't use this design, it's close enough), first checking all the grounds, and then testing the powered up amp without tubes, with the rectifier tube only, and then the whole lot. You have to be very careful here, as you are dealing with lethal voltage levels (500V DC across that large blue capacitor). In testing I accidentally shorted to ground at one point and tripped an RCD in Makespace, which took out power to more things than I think anyone expected (i.e., there was more items on the electronics bench circuit than people realised). This caused a bench power isolation box to be procured, and delayed further testing until that arrived.

But, late on Friday evening, with the assistance of a couple of more experienced analog engineers (one of the benefits of working in a community workshop) I resumed the testing process, and brought the amp up in various stages until we got to the wonderful point where we plugged in a guitar and made sounds come out the speaker: I've now effectively got an entirely self made signal chain!

I can't consider it finished yet, though. One of the potentiometers used for the volume turned out to be a bit of a dud, so needs replacing, and similarly for the power indicator bulb. I've ordered replacements, and once they're in it'll actually be finished, and I can make a little demo video.

Still, a great feeling of achievement!

I spent a good chunk of the early part of the week coming up with BoMs for the three guitars I've been asked to spec as part of my prototype run, so that I could give a proper price quote to people. It was two guitars last week, but right at the end of the week a good friend asked for one too, so now we're at potentially three guitars!

Doing the BoM, as I've highlighted before, is a really good process. It means you know what you will need, can get a cost estimate, but also here I could send a list of bits to the clients to make sure we both have a matched vision for the guitar. Whilst the renderings help, a list of actual parts also brings out points that each side assumed were going to be done in different ways. By teasing those out early you avoid frustration later.

Now I just need to get final sign off and deposits sorted, then I can get ordering parts!

One of the things I want to improve on in the next round of guitars is the neck design. One of the guitars specced has a one piece maple neck which I've not built before, and the other two are short scale (24") necks, and that means the truss rod geometries will need tweaking as there's less room to play with than I'm used to on a 25.5" scale length. Thus I spent a bunch of time trying out various scenarios in Fusion 360 as to how I might fit the truss rod. One of the things I learned from the amp was that just because you can get pieces to fit in CAD doesn't mean they'll actually be fit-able in reality, so I've been keeping a close eye on how I'd actually assemble bits, which is where the tricky bits are here.

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Having done that, I also tried something new for me: 3D machine routing of wood. For all my previous guitars I've effectively done 2D cuts on the CNC router and then finished by hand. And whilst I find that process the most satisfying, there are a couple of bits where it doesn't give me the finish I want (notably the transition from fretboard to headstock), but also for the thinline models I have planned where you have a belly carve, I'll need to do the roughing with the CNC lest I make a guitar body that looks like swiss cheese. Note that lots of people do the fretboard to headstock curve using a drum sander fine, it's just that at the community workshop I'm in we don't have one, so I have to look for what tools we do have that'll let me do what I want. Similarly we don't have a planar thicknesser (a machine to let you make a block of wood a particular thickness), but I do have a CNC router and a 1" router bit, which has the same end result.

Anyway, I found a bit of scrap in the workshop and mocked up some suitable curves in Fusion 360 like so:

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and then after a bit of trying various tolling patterns in the Fusion 360 CAM editor, ran the design through the CNC router and ended up with this:

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There's a video on my instagram if you want to see a clip of the CNC Router in action. Overall quite pleased. The curves are a little rough (the rut on the top right was from the scrap rather than an artefact of the routing), but they'll sand down fine. I used a flat end mill bit rather than a ball end mill bit that I should have used, so that it came out as smooth as it did was pretty good, and now I know this will work I can order one.

I ended the week with a bit of fun: I headed over to The Guitar Show at Birmingham to go and see what was doing - partly to look out for new suppliers of bits for my guitar builds, but also just to go see/hear some awesome bits.


One of the exhibiters there was the ever awesome Fidelity Guitars, a Cambridge based shop making these great models that have a 70s Italian vibe to them (you can see their demo guy Brian playing one of their JB series above). Matt had a nice demo rig, with a Hampstead amp plugged into a bunch of pedals from small UK manufacturers like Zander Circuits, Tate FX, Thorpy FX, and Hampstead as well. I had a good five minutes rocking through the toys. The combination of Matt's JB model, that Hamstead amp, and Hamstead's soon to be released Odyssey overdrive pedal was sublime. I've played Matt's guitars before, and they sound amazing, but the Hamstead amp delivered amazing cleans when cranked, and you could get a good dirty blues sound with the Odyssey. As much as I like building and playing my own guitars, it's always fun to play with other toys :)