Another early morning jam in B over coffee

Still feeling inspired by the addition of the TC Electronic Hall of Fame 2 pedal to my rig, here's another morning practice jam whilst I have my coffee:

Mostly I play around in a blues style, which is quite a nice simple structure to follow and improvise open, but I'm very taken with using jazz style chords likes 9ths and 7ths with a percussive pattern to give it a less common sound. I suspect the percussive nature is a natural follow on from mostly jamming over a looper pedal without a drum track, but its interesting to see how ones playing evolves over time.

Help Kickstart IKARI's first album

The band IKARI are running a Kickstarted for their first album, Shapes & Sound, and they've just reached the half way mark, raising £650 out of the needed £1300. If my brother being one of their guitarists wasn't enough, IKARI have a special place in my heart ever since I went to see them gig at King Tut's with a guitar I built, so I was quick in with my pledge to see what they can do in a full album having heard their two singles to date: Ghosts and Ocean Waves.

If that music is your thing, then why not go and help a band trying to get their music out? I need them to become a success so I can start shipping the Tristan Dales signature IKARI tele ;)

Some early morning jam over coffee

In addition to building guitars, I do actually try to play them too. I've been taking lessons for the last couple of years, and whilst in no way a master, I've got to a point where I can do a little bit of improv blues when the mood takes me - as it did this morning whilst having my  morning cup of coffee.

Here I'm jamming on my Blues Deluxe guitar, plugged into the amp I made earlier this year, running through the Keeley D&M Drive, into my new Hall of Fame 2 reverb by TC Electronic and then into my most used pedal, the Ditto x2 Looper, also by TC Electronic. 

A looper in my mind is an essential practice pedal, letting you lay down a rhythm track and then play some lead over it - whilst backing tracks may offer more variety, there's something nice about the instantaneous nature of using a looper to put down whatever inspires you at that moment. The Ditto x2 also lets you load loops onto it, so I have a folder on my computer of drum beats at different bpm and bar lengths, so I can also have drum + rhythm + lead. But mostly I just play along like this of a morning.

Whilst I don't regret not adding reverb to my first amp build (always best not to get too complicated the first time you do something) I do miss having reverb, and good reverb at that. I've played with some reverb effects via my iPad using the OMEC Teleport, and it's just made me appreciate how getting a nice sounding reverb is quite hard. So I finally caved in and got a dedicated reverb pedal, and I'm so happy with my initial playing with the Hall of Fame 2. I look forward to playing with tone prints and creating my own reverbs through that at some point, but right now I'm just enjoying the lush tones from the built in spring and room reverbs.

Another week out the shop

This week was in two halves: a trip to Helsinki for vacation, and then spent in a field with 2000 fellow nerds at EMFCamp. Hopefully I'm now back in Cambridge for a bit so will get more time to do actual building, but this last week has had some quite interesting guitar moments in it, so here's a look at those.


One of the things I haven’t done much of is meeting proper luthiers to understand how it is they work and build things. I get a lot from talking to people online and watching youtube etc., but there’s still something about just having a conversation with someone practiced in the art of whatever you’re interested in that means you learn a lot very quickly.

In Cambridge I’ve been fortunate enough to meet Matt from Fidelity Guitars, who makes wonderful solid body electrics, but that’s the only one I’ve met. Additionally, I’m actually getting the urge one day to move away from the constraints of solid bodies into at least semi-hollow and carved toped guitars, just to move in a direction that is less common, and as part of that I’ve been wanting to meet people who 

Thus, whenever I travel anywhere I always check to see if there’s any local guitar builders. In Helsinki I spotted Lottonen, who not only builds guitars (mostly beautiful acoustics), but also makes archtops. So, out of nothing I dropped them an email explaining who I was and asking would it be possible to visit and take a look at how they made things, and very kindly Juha Lottonen agreed, and so I delightedly found myself on the last day of our Helsinki trip going over to Lottonen’s workshop to see how they did things.

IMG_1419.jpg

Juha was very kind and generous with both his time and knowledge, explaining to me how they made their arch top guitars, showing me around their workshop (which is quite different to the community workshop I work in terms of tool availability), and in general he answered my questions on how they approached things on their guitars.

It was a humbling experience: talking to Juha I learned a lot, all the while I was aware that I’m there keeping him from doing actual work, so I was doubly appreciative not just of the knowledge he shared but also of the time he gave me. One of the things we discussed towards the end is how generous with knowledge the guitar building community is, which is certainly true. I only could get started on this because of people like Crimson Guitars and Highline Guitars and many others posting tutorials and explanations on youtube, and from the help I’ve had over time from people online, and then both Matt and Juha. 

I’m trying to do my own little bit to share back with this blog, and by helping people at Makespace whenever I can. I think the guitar community understands that it’s not the knowledge that sets people apart, it’s the execution of that knowledge and the attention to detail and the care and attention. As such, we’re happy to share what we know, as it’ll let us see other people make cool things and we’ll one day benefit from the return favour.

Anyway, it was a wonderful way to spend some time with someone so knowledgeable. I just hope I can do the learning justice at some point in the near future.


Related to the topic of sharing knowledge is EMFCamp. EMFCamp is a bi-annual festival of all things geeky and nerdy and maker-y, with about 2000 attendees (so I was told, I didn't count them all) and lasting two and a half days. There were talks on three stages running all day; regular workshops on things like electronics, metalwork, and knitting; a race track for home made racers running events throughout the weekend; and lots of groups set up their own villages around specific topics in the camp site (e.g., amateur radio, different hackspaces, and so forth). 

IMG_1473.jpg

I last went to EMFCamp in 2014, and it’s come along a long way since then. Whilst I understand the organisers struggled with being let down by suppliers this year, as an attendee I wasn't particularly aware of this, and had a great time. In particular I liked how there was room to just chill out more between talks and events - the weather was good and you could just sit on the grass, under a tree, or in a small geodesic dome (it is that kind of event). I got to catch up with people who I’d not seen for a while, and meet some new friends. I had a guitar with me so occasionally I'd just sit down, chill out and play, and pass the guitar over to others to play if they stopped by.

IMG_1481.jpg

I saw some great talks: building physical models of landscapes from LiDAR scans, making electronic music with open source software, and the trials of entering robot wars (I actually know the team who did this, but it was great to learn more of their struggles despite the brave face they put on it). The full list of talks and the videos of them are available here.

I was also giving a talk this year, on the topic of how to get started in a new domain: how to try and prevent yourself getting overwhelmed, and how to pull yourself through when things go wrong. Basically trying to encourage people who’d seen something cool at EMFCamp that they wanted to do but thought they couldn’t do to give it a try. You can see the talk here if you’re at all interested.

Screen Shot 2018-09-03 at 13.42.50.png

(Sorry there's not a better picture - I was incredibly nervous about talking to such a large audience, and thus forgot to try and get someone to take a picture of me on stage).

At the heart of the talk is just a few simple rules that I’ve applied to learning to build guitars to try prevent myself getting stuck and giving up. Mostly this is around doing just a little bit out of my comfort zone on each guitar, knowing that I’ll eventually get to building my own custom designed guitars from scratch one day, but if I try that on the first guitar I’ll get overwhelmed and give up. I also have made sure I’m part of a community - both the local Makespace community and the wider guitar builder commit via things like Instagram, both of which help you get knowledge, inspiration, and support on the days when things go wrong.

It seemed to go well, and afterwards I met some people who said that it had resonated with them: that they’d wanted to get into various things but felt overwhelmed or unsure how to get started and the tools. The best reaction though was from a chap at the Newcastle makerspace who is has made his own pickup winding machine, and gave me an example of his work, which was very kind of him.

IMG_1480.jpg

We have a chat and hopefully at some point I can find time to visit Newcastle and have a go at pickup winding (most likely to learn just how hard it actually is :).

A week out the shop

As I mentioned last week, this has been not a very guitar focussed week: I’ve been trying to close up one of the features for a company I’m doing software contracting for, and now I’m writing this from Helsinki, where I’m taking a quick break for a few days. You’ll be pleased to know we have seen some guitar based modern art again already, despite being here less than 24 hours :)

On the guitar building front though I did get a bunch of bits in the post for a big experiment I have planned for next month. I’m still unhappy with the state of the mustang dynamic vibrato on the prototype offset I built, and I can’t figure out why. I did take it to someone more experienced with guitars with tremolos and he was very dismissive of it. As an engineer though I want to understand why it’s wrong and how to fix it. Part of the issue is that I can’t see what’s happening inside the vibrato when its mounted, and the other part is it’s quite hard to change the variables (e.g., spring tension) and observe the change. Thus, it’s time for some science.

My plan is to make a proxy offset body that has the neck pocket and bridge mount in the right place, but to cut the bridge mount all the way through, and then cap it with clear acrylic at the correct depth: this will let me see what’s happening inside, but also letting me know if the bridge is not working due to hitting the body at some point inside. In the post I’ve got another bridge/vibrato unit by another company, and a set of lighter and heavier springs. I hope to thus actually play around and try properly understand what is going on with my unit that makes it so unstable.

The whole experience with this Mustang bridge has made me appreciate how ignorant I am about other guitars once I move outside the Fender style with fixed bridge space, so I’ve started trying to find broken guitars to fix up as a learning exercise. Unfortunately scouring eBay, gumtree, etc. hasn’t turned up much yet: I guess most people just put broken guitars in the bin. But as an aim I’d like to do some more fixing up guitars I’m less familiar with to learn how they’re put together.

But both of these a projects are for later in September now. The next few days will be in Helsinki, and then EMFCamp for the weekend. After that I really want to get the fretboards cut for the two offsets I have in progress, which will be the priority once back in Cambridge.

 

A week in the shop, and a week in Nantes

Return of the weeknotes, though I fear the next couple of weeks will be sparse guitar work wise due to August being a month of travel. The week before last I had family visiting for much of the week that kept me busy, and then last week I was on actual vacation in Nantes, France, enjoying a combination of the annual arts festival and just switching off and indulging in things like cooking local produce from the market in our rented apartment. Between these events I failed to write up what I did before all this week, so here it is below.

This coming week I’ll be mostly doing paid software work whilst I'm at home, and then I’m in Helsinki for a few days (tagging along with my other half who is out there for work), before heading to EMFCamp, a weekend long hacker festival where I’ll be talking about how I got started in a new domain again. If you happen to be at EMFCamp do say hello!

Anyway, what is happened last couple of weeks, and normal service should resume in September.


I started the previous week with two guitars hung up and ready to move forward: one made from parts the CNC router had tried to destroy and I’d patched, and the actual bits from the first of the commissioned offsets (both of which need names). What unites them both at this stage is that they need fretboards next.

In the past I’ve radiused fretboards by hand using a radiused sanding block, but you have to be very careful not to introduce any bias as you do so: it’s far too easy to take a little off one side more than the other at the diagonally opposite corners, due to how your arm moves relative to your body even when you think you’re pushing straight. The common solution to this is to use a jig to make sure you don’t go down too much at any point, but I wondered if perhaps I could use the CNC router to radius the fretboard roughly, and then just use sanding block to remove the machine marks rather than the bulk of the wood.

Whilst it sounds simple enough, the worry I had is that, unlike most people, I use a laser cutter to etch guide lines for my saw to cut the frets. Being an optical device a laser cutter has an ideal distance above the cutting surface to ensure it is properly focussed: if I radius first then my cutting surface will no longer be flat, and thus I can't guarantee it'll be in focus at the edges. This might mean the grooves I etch aren't deep enough to sit the saw in to get it started.

To test this I got a bit of scrap wood and used my radius block on it shape it like a fretboard, and then I used the laser cutter at various powers to etch the 0.5mm slot I’d normally use to create my saw blade guide. You can see the results here:

IMG_1056.jpg

First thing to note: because I used ply wood and just did a quick job of the radiusing you can see the contour lines show the biasing effect I’m talking about. As I’m right handed you can see despite thinking I was sanding straight I’m actually going sort of from bottom right to top left slightly. This is what I’m trying to avoid with all this talk of jigs or CNCing.

Next thing to note: the radiusing had no notable effect on the slot I etch, proving my fears were unfounded. The fall off at either side is only around 1.5 mm, and that isn’t enough to cause the laser to lose focus. I did however find that I had to be much more careful when cutting the slots with the saw. Compared to cutting the slots before radiusing the board it was much easier to slip out of the grove, as you have a smaller contact point with the wood when sawing. 

Overall it worked a charm though, albeit with the caveat you need to be extra slow when sawing the slots. The frets you see in the above picture are held firm without glue, so that’s a green light on this approach in general.

IMG_1057.jpg

Next up then is to get the CNC router to make a fretboard with a radius, or more specifically to get Fusion 360 to generate the toolpaths to do so. This turned out to be much harder than I had anticipated, and I lost easily a day of work just trying to tweak toolpaths to ensure Fusion didn’t do something I didn’t want.

Screen Shot 2018-08-20 at 20.30.50.png

Fusion 360 in general is more aggressive with its tool moves than I like for guitar work: it’ll happily assume it can cut through 10mm of wood in a single pass, whereas typically I want it to move more slowly to ensure a nice finish. It took me quite a while to get Fusion not to do occasional plunges through the material, which whilst not incorrect would have not left me with the finish I wanted. It was a nice reminder that whilst I’ve used Fusion quite heavily for the last year it’s mostly within a set of regular operations, and outside that I’m still a bit of a newbie.


Once I had a toolpath, I then set out to make a test fretboard. I found a old maple fretboard blank I had in stock, and set about cutting it out, trying to fit this in at the last moment before I went on vacation. At this point I also had family visiting, and my brother and brother-in-law asked to watch, so I set them up with PPE and got started.

Initially things went well, but in the end due to a combination of being tired and feeling watched I made a mistake, resulting in my fretboard blank being ruined. As is always the way with a new set of toolpaths, I end up tweaking them on the fly as I learn more about what each pass is doing. On this occasion I realised that the bulk clearing paths for the fretboard didn’t account for the initial levelling paths I’d created to get the blank down from 9mm to the 6mm required. So, rather than watching the CNC router cut air for a good 10 minutes, I aborted that part of the run and went back to Fusion 360, tweaked the tool paths to start further down and set things going again. Unfortunately, I failed to double check what the updated toolpaths would do, and failed to spot that I’d ended up generating toolpaths that cut behind the headstock transition and through the fretboard itself. Doh.

IMG_1097.jpg

In the above image you can see on the left the headstock transition is a weird island on its own rather than a ramp down at the end of the fretboard. At least this was my mistake rather than a failure of the CNC router: me being wrong is generally easier to fix than the CNC router being wrong. But all the same, as this was the last free evening before heading to France, I was quite frustrated not to have made at least one fretboard before I went away. As ever, this just reinforces the measure, measure, cut mantra: due to being tired and the pressures of being watched I’d not double checked my toolpaths, so I only have myself to blame.

I quickly ordered a couple of more blanks before going away, so I’ll see if I can sneak in time this week to do another test cut of my fretboard design.


However, in general we had a fun week with my family around. I introduced my nieces, Leah and Sarah, to 3D printing, letting them pick an item from thingiverse (they went for a Pokemon) and printing it out there and then. I think it's one thing to hear of 3D printers, but it's another thing to actually see a thing you picked appear out of nowhere.

IMG_1081.jpg

With luck that'll inspire them to make things themselves one day.

I also took an afternoon out to take my brother Tristan and Sarah to a rehearsal studio for an afternoon where we had quite a fun jam session. Tristan is a very talented guitarist, playing with IKARI, and ordered and plays the second guitar I ever made, and Sarah has been taking guitar lessons for quite a while now, so it seemed a reasonable idea to collect up the guitars I had and my amp and find somewhere we could make some noise.

IMG_1079.jpg

Tris hadn't yet had a go on my amplifier, so he gave that a going over. and seemed to like it for the cleans on his IKARI parts (I have to confess, I wasn't aware he did cleans, but you learn something every day ;).

It was a bit last minute, so I failed to secure a left handed guitar for Sarah in time, but she did a valiant attempt with the right handed guitars we took along. In addition to playing some of the stuff she already knew, I managed to teach her the blues scales enough that we could have a simple jam along together.

IMG_1116.jpg

Tris also taught me the rhythm part to Ocean Waves and we jammed that together. A great afternoon of fun just playing guitars with family, and a reminder of why the guitars are worth all the effort!


Much to my surprise, although I took the vacation time to totally switch off, there was a surprising amount of cool guitar stuff at the art festival. First was Fluides, by Céleste Boursier-Mougenot, where in a netted space filled with dozens of small birds that would come to rest upon a number of face up mounted guitars, which were wired through delays and reverbs to amplifiers. Each time a bird would land on a guitar or shuffle along the neck you’d get a lovely ambience sound piece.

In Daniel Firman’s exhibition, Outside, one of the pieces was called Drone, which featured three telecasters being spun at speed from their headstocks, with weighted spindles that would occasionally strum them. The guitars were each tuned to a different range, so the effect was somewhere between a didgeridoo and Mongolian throat singing. 

Finally, I was surprised to find out in the rural areas south east of Nantes a giant Les Paul emerging from a round about:

IMG_4263.jpg

It turns out that Hellfest, a massive annual heavy metal festival, takes please each year in the middle of the Loire vineyards. All the villages in this area compete on decorated roundabouts - I assume this one must be one of the more unusual ones!

 

Wilderness highlights

Every year for the last few years my other half and me join a few friends for Wilderness Festival, an event spanning four days and a wide array of cultural activities: music, spoken word, theatre, dance, swimming in the lake, a very silly cricket match, and lots of nice food and drink. Also, being in a field outside somewhere in Oxfordshire, the cell network can’t cope with the sudden influx of 30000 mobile phones and you have no Internet access for most the event, so you can just switch off and immerse yourself in all the fun thing on offer.

IMG_1029.jpg

What’s on music-wise varies from year to year. In particular, there’s one stage (this year called The Hereafter Stage) which seems to get a very different set of programming each year, so hasn’t always been to my tastes; but this year it was mostly focussed around blues rock, so Laura and I spent a lot of time hanging out there. Pretty much all the bands were small up and coming bands, none of which I’d heard of before, but now I’m slowly working my way through the list I build up. Here’s a few of the 17 bands we saw over the weekend that I recommend you check out, just in the order I saw them, so you can make up your own mind about which ones are the best.

  • Elles Bailey is a great blues vocalist and made a great start to the festival with her songs
  • Cosmic Strip were more psych-rock than blues-rock, but their general spirit fit in well on the Hereafter stage. Sonically very different to most things we listened to, with more ambient sounds and delays segueing to more straight rock, but great stuff all the same. They also did a cover of a Dandy Warhols song, which is a sure fire way to seal the deal for a big Dandy’s fan like myself.
  • John Fairhurst did some amazing solo guitar work, just him and his resonator guitar, lots of blues textured fingerpicking songs, often without lyrics but still very captivating (which solo guitar can be quite hit and miss with). We unfortunately missed his electric set later on the last day, but definitely a very talented guitarist worth checking out.
  • True Strays are a crazy bunch: we saw them late afternoon, after they’d driven up from Brighton starting out at 6am having just finished a festival they were hosting, and still put on a rocking show full of energy. More at the rock end of blues rock, it was still great music with heart; their singer/guitarist rocked some great slide guitar on another resonator guitar. They’ve just put out an EP on band camp, so you can go listen to that. 
  • Whiskey Shivers are a five piece from Austin, TX that describe themselves as Trashgrass. For their last two songs, having already done a high energy set that got the crowd on their feet,  they got off stage and into the crowd and just played acoustically, finishing with a gentle rendition of Daneil Johnston’s True Love Will Find You In The End, which was such a touching way for the last act of our festival to end.

A week in the shop and in a field

Last week I cut the neck for guitar #5, the much delayed first commission custom build, and this week I cut the body. As stated last week, I still don’t trust the CNC Router at Makespace particularly, but between the desire to make some progress and my now better understanding of the machine itself, I felt time had come to re-roll the dice. I was more nervous with the body compared to the neck for two reasons: firstly, although the wood from which the neck is cut is more expensive in monetary terms, a body blank represents half a day to a day of work by time I get to this point, so is more expensive to me personally; secondly, the body requires more cuts and more complex cuts than the neck, so more opportunity for the CNC Router to get confused and do the wrong thing.

However, like the proverbial kettle that never boils, it seems that by watching the CNC router like a hawk for the entire process (my thumb hovering over the abort button at all times), I was able to stave off failure, and the body came out all okay.

There's much relief on my behalf that this is done. Now all I need to do is make the fretboard and we’re on route to getting this guitar onto the hand making part.

A couple of learnings from making the body. Firstly, I utilised the discovery I documented in last week’s notes that the machine’s ability to find the origin after it’s been powered off and on is more accurate than people suspected, to within a tenth of a millimetre. This meant I was able to make the guitar body over two days due to being short of time, rather than having to do it all in one session (CNC routing a body like this can easily take 4 or 5 hours all in). As the saying goes, the proof is in the pudding, and after I finished machining the body the seam where it was cut from the front side on day one and the rear side on day two is very close: as closed as I’d expect had I flipped it anyway, so I’m very happy there.

IMG_0883.jpg

The other learning is in the triangular tab shape there. Most design tools insert rectangular tabs to hold pieces being cut out in place, but the down side of rectangular tabs is that the tool is briefly paused in the X/Y plane whilst it moves up and then later down, and at this point it will wobble slightly, leaving a groove that has to be sanded out. I spotted Fusion 360 has an option to make triangular tabs, which mean that the tool never has to dwell in one position, and so there’s no ghost grooves around this tab.

Next up for this body and neck now will be sanding. I finally gave in trying to sand by hand, and upon the advice of Matt I’ve got myself a proper orbital sander along with some professional quality sanding disks, so hopefully making the body nice and polished will be a lot easier.


This was about the only progress I made in the shop, as I spent the later half of the week watching live music for a change over at Wilderness Festival down in Oxfordshire. In the past there’s not been a wealth of music that has been of the style I’d normally go for (though there’s been good stuff that I’ve discovered that way), but this year they had a new stage, called the Hereafter stage, which was programmed with lots of great blues rock bands.

IMG_1029.jpg

I’ll write up a list of my faves here shortly once I’ve caught up from being in a field without Internet for 4 days.

A week in the shop

This blog seems to be rapidly turning into a blog about CNC routers rather than guitars, for which I can but apologise, but it just reflects the reality of my situation at the moment, in that it continues to occupy my time as I try and find a way to get a reliable, repeatable, and efficient way to make guitars. Although I’ve convinced myself I can make bits by hand now, it’s not particularly efficient, and I do think quality wise certain bits are more reliably/repeatably produced on the CNC router, even if I’m using it for mostly roughing things out.

This week I decided that the misbehaving CNC router at Makespace is what it is, and given I’ve failed to find an ready alternative I’m going to try push through at Makespace with what I have. Before doing any guitar building on it, I had two tasks I wanted to get done on the CNC router care/maintenance front. Firstly, I spent an afternoon creating a new sacrificial bed for the CNC router. What should have been a simple job turned out to be more complicated due to the way most CAM tools work. I’ve documented all of this in another post, so if you’re interested head over there, but the end result was the CNC router had a nice new sacrificial bed that was actually level, unlike the old worn one which was all over the place.

IMG_0835.jpg

Having levelled the bed, I then set about another experiment, which was to try measure how accurately the machine is in getting back to the same set of positions on the bed after you switch it on and off. You might assume that the CNC router knows where it is at all times, but that’s not the case: when you power it on each time the controller logic knows nothing about the location of the cutting arm - it has no way of measuring the arm's location at any point in time. Instead when you power it on the controller will move the arm into one of the corners until it can do so no more. Once it’s done this it then knows where the origin is on the bed, and from then on it keeps track of how how much it has moved the arm by, so it can then keep track of the arm from here on out. But if I switch off the machine and ask it to find the origin again, how accurate is that? My motivation is that it seems a lot of the router failures we’ve had are with more complicated multi-stage designs, and so if I can reset the machine between stages perhaps it’s less likely to ruin my pieces. 

The way the CNC router detects that the arm is in the corner is done with a set of physical switches: the CNC Router sets the motors going towards the origin and when the switches are pressed it stops, so how accurate the origin is is down to how accurate these switches are. Opinion seemed to be divided amongst people I asked, some suggesting it might be as much as 0.5 mm out after a power cycle, which would be a bit too inaccurate for my use case. But there’s nothing like testing something yourself, so I made a simple design referenced at the machine origin and just ran it on the same bit of wood mounted in the same position 5 times, between each run I’d power off the machine and get it to reset itself.

IMG_0842.jpg

The end result, whilst not hugely rigorous, indicates that the reset is accurate down to around 0.1 mm, which actually for guitar building is acceptable. At some point I’ll repeat the test with a more accurate measuring device than the callipers I used, but the initial results are promising. Knowing I can turn the machine off and on again between phases starts to give me a route to more confidence in getting the machine to make something.


But I’ve finally had enough CNC router naval gazing. We're drifting into August and I've still not produced the pair of commissioned guitars I’d aimed to have completed by May, and I decided to take the risk with the CNC router as it is, tampered by all the knowledge I've gained about how the router works and what its limits are in the last few months, and start on guitar #5 again. This was the original request to build an offset guitar that has pretty much defined all my guitar building this year. It was this guitar that the CNC router started failing on, hence the delay and why this blog is now more about CNC routers than guitars.

Even though I don’t understand why the machine fails properly, we have some ideas, and I do know that when it fails there is usually some sort of quick indicator before it does so, so if I just watch the machine like a hawk through the cutting process, there’s a good chance I can stop it if it starts going wrong. I decided to go all in, and broke out the nice bit of birds eye maple destined for the neck of guitar #5 and cut the neck.

IMG_0866.jpg

The birds-eye maple is really lovely up close:

IMG_0865.jpg

All went well for the most part. I did abort one of the CNC router phases due to a suspicious noise happening at one point, and so did have to re-start that stage, but an hour or so after I started I had a neck cut out.

IMG_0867.jpg

So, some success after all our failures up til now. Next up will be the body for guitar #5. My aim is to get the main bits for this guitar cut out this coming week before I vanish to Wilderness festival. 


I did also find some time to take the damaged body and damaged neck that I’d been repairing and sand them down to get the neck to fit the body spot on. This here is a picture of the neck held in just by friction alone, which is always a good sign.

IMG_0845.jpg

I'll be interesting to compare this body, where I did the comfort carves by hand, with the one I hope to do on the CNC router in the coming week, and see which is more pleasing :)


I wanted to try a fuzz pedal a while back (I was playing lots of White Stripes at the time) so I bought a fuzz pedal kit from jed's pedals (obviously someone like me struggles to buy ready made things when they can have an excuse to build something), and I've been trying to 3D print a case for it. However, the epic heat wave has really been making it hard: the design is not really any different to the ones I did for the clock a few weeks back, but I’ve had about a 75% failure rate, which I put down to the high temperatures causing the printers to not want to play ball. I have finally managed to get a case printed out though for test fitting:

IMG_0820.jpg

Seems strong enough, which I wasn't sure about. Fun thing about the lettering: that font I've used for the name "Fuzz Zero" should have straight edges, but instead it's got this cool wobble on the lines. I'd love to claim this was some original graphic design on my behalf, but it's a pleasant side effect of me setting the laser cutter to run too fast for cutting outline, and that decaying wave you see is the mirror in the laser cutter wobbling as it is forced to change speed too quickly (I'd set the machine to etching speeds, but then set it to do outlines by mistake).

Clearly plastic and acrylic don’t make for the best case in terms of shielding, but eventually I’ll probably make this out of a nice wood and copper shield the innards. Next is to find a spare half hour at some point to solder the board up!

 

How to level a CNC router sacrificial bed with Fusion 360

I’m now one of the maintainers of the CNC Router at the Cambridge Makespace community workshop, and one of my first tasks as maintainer has been to replace the sacrificial bed that is mounted on the CNC router.

IMG_0835.jpg

The sacrificial bed is the large wood base that is permanently mounted on the router to which work pieces are then in turn mounted (which is nice and fresh in the above picture, taken after I'd replaced it). Although in theory you can mount things to the metal bed on the router, for the majority of jobs done in a space like ours (particularly given our machine is only rated for wood and plastic work) a sacrificial bed which things can be screwed to readily simplifies machine use somewhat.

The downside is that over time the sacrificial bed is worn away by people screwing things into it and cutting through into the bed. At which point you face an interesting challenge - how do you make a new bed that is by definition exactly the size of the working area of the machine? It turns out that doing this in Fusion 360 required some non-obvious trickery, so I thought I’d write it up. This is what a well loved sacrificial bed ends up looking like:

IMG_0836.jpg

The first thing I did when I started this task was look for existing design files that I could re-use. Unfortunately they seemed to have been lost over the course of previous CNC router owners coming and going, so I had to make my own. Thus I broke out the callipers and fired up Fusion 360 and recreated the bits of the CNC router I cared about: The metal base onto which the sacrificial bed is mounted, plus a model of the existing sacrificial bed layout wrt screw holes for mounting etc.

Screen Shot 2018-07-27 at 09.54.57.png

The bed is made from 16 metal extrusions, which are nicely symmetrical, but with the notable feature that there is no center slot, so the two middle screw holes have to be staggered either side. But that aside it’s a fairly simple thing to model. To try and and save the next person having to recreate the design yet again, I shared this design with the Makespace community - a nice upside to Fusion 360’s cloud based nature.


Having made the model, the next step was to make the CNC router make the new sacrificial bed. This is done in two parts:

  1. Firstly, we mount the new bed on the old bed and make the counter sunk screw holes to let us mount the new sacrificial bed on the metal base
  2. Secondly, we then face off the new sacrificial bed to make sure it’s completely flat

For those not familiar with the term, facing off just means making sure the material is absolutely flat, so we mill down the surface to remove any variation due to imperfections in the material or the base its mounted on.

The first stage was easy enough. Although the sacrificial bed is quite large, the mount holes are by nature within the area of movement for the CNC router. Thus I simply screwed the new bed onto the old sacrificial bed, cut the mount holes, and then was able to quickly swap the old sacrificial bed out for the new one.

The second stage though proved quite problematic: here we need to go edge to edge on the new sacrificial bed and the material size is actually 20 mm bigger than the movement size of the CNC router. This is okay, as I have a 1 inch (25.4 mm) wide router bit for levelling jobs like this, so the movement of the machine head plus the diameter of my router bit means in theory we can face off the new sacrificial bed without problem. The problem however is trying to get the software side of things to understand those constraints. I spent a good 90 minutes with both Fusion 360 and Vectric VCarve Pro trying to find an elegant way to express what I wanted to do with no joy. The fundamental problem is that neither bit of software understands the constraints of the machine you’re using, just the constraints of the material.

Screen Shot 2018-07-27 at 09.27.40.png

Look at the above picture as an example: here I’ve told Fusion 360 that I want to face off the sacrificial bed using my 1 inch router bit. You can see that it’s made this nice pattern that relies on going off the side of the material and back in again. I can’t do that in this case as I’m at the limit of my machine’s bed here: there’s no room in which to execute that turn, and I failed to find a way to express that constraint to Fusion 360 in any of the options.

I tried some other tool path generation techniques in Fusion, for example using its adaptive clearing method to just say make the surface of the material match the model, which should be equivalent to facing off here. Here I hit another issue with Fusion 360, in that it still wants to enter the material from the side. Even if I try explicitly telling Fusion I do want’t to have a lead in, it still has some partial path coming in from the side. 

Screen Shot 2018-07-27 at 09.33.44.png

After much fiddling, I managed to stumble across a solution. I reasoned that if the sacrificial bed was treated like a pocket, then surely it’d not execute a lead in manoeuvre, as in pockets you'd normally hit a wall doing so. Thus I set my piece origin to the center of the material rather than a corner as I’d normally do, and used the 2D pocket path, and indeed there was no lead in issue, but it still insisted on going outside the material at first:

Screen Shot 2018-07-27 at 09.39.02.png

Because there are no walls on the edge of this pocket, Fusion 360 reasonably assumed it could do that. In the end I realised that I could control the step over amount for the spiral shape it is making, and by playing with that number to make it create a slightly tighter spiral I managed to get a tool path that remained within the material near perfectly.

Screen Shot 2018-07-27 at 09.42.00.png

Thus I was able to execute this as my face off pattern and I got the nice finished sacrificial bed you see in the opening picture of this post.


Ultimately the problem here was that I couldn’t find any way to teach Fusion 360 about my machine limits (and it’s not alone in this issue, it’s just that I happen to use Fusion 360, I hit similar issues in my brief play with VCarve Pro to see if it was more sensible). I was getting to the stage where the irrational part of my brain was going to write some software to generate a bed levelling pattern based on machine limits rather than material limits - and the whole point of getting into woodwork was as an escape from writing software!

The other frustration with this kind of problem is that it’s not until you try run your tool path on the CNC router that you have any sense of whether it’ll work or not: do you get the dreaded "x-axis out of range!" message or not. I did manage to work out that using a combination of ncviewer.com to visualise my tool paths and reading the low level g-code I could take a good stab at whether a design would work or not, but reading g-code is not for the fainthearted, and ultimately the whole process was a user experience nightmare for what should have been a simple enough task.