DIY Modular Synth: Making Module Panels

As you’ll have seen from some of my recent posts, I’ve recently taken to making my modular panels out of aluminium. This post describes the process that I go through to make each one.

Finding the best approach

By far the best approach to making good-looking, durable and accurate panels for your DIY modular is to get someone else with good precision engineering skills to do it for you. However, this method will come with drawbacks:

  • You may well have to pay for the work, and you won’t have control of the cost
  • If you don’t have to pay for it, you may have to wait for results, effectively putting your build schedule into someone else’s control
  • You’ll probably have to develop a whole bunch of extra skills around CAD drawing; effectively, you’re trading acquiring one set of skills (making) for another (describing what you want to make)
  • Where’s the fun in any of that?

However, there are also pitfalls at the opposite end of the spectrum – doing the whole job yourself:

  • Precision and consistency is hard to achieve on a budget
  • Cutting corners working with metal is, potentially, dangerously stupid
  • Seriously – who wants to look at a wonky modular?

In between these extremes is what I think is the perfect middle ground – I found a local precision engineering company willing to do a small order of 1U and 2U blanks for a very reasonable outlay, leaving me with the relatively straightforward task of drilling holes and making my panels look pretty. Since the tooling for this is well within the reach of the entry-level DIY-er, this seemed like a good approach to me.

The process in brief

  • Find a firm that can create your blanks for you (actually easier than I expected)
  • Draw your blank panels. Show dimensions for everything
  • Give them your drawings and order a bunch of blanks (I ordered 20 x 1U and 10 x 2U)
  • Wait for a week or two…

When your blanks have arrived, you can start making! For each panel you’ll need to

  • Make a drilling guide
  • Mark the panel with where to drill
  • Drill!
  • Clean up
  • Finish
  • Lacquer
  • Make a drawing of your control markings and text
  • Transfer this to the panel (potentially – really, really hard)

Let’s look at each of these steps in more detail. I’ll introduce tools, techniques and tips as we go along.

Finding a supplier for blank panels

This was surprisingly straightforward. I used Google to search for “precision metal cutting Coventry” and visited the websites for the top dozen results. Some were immediately ruled out as being way too high-end or large-scale but there were still a good half-dozen candidates. Then I used the contact forms or contact email addresses for each of the remaining firms to send a brief introduction to who I am, what I was trying to achieve and that yes, it would be a small order, would they be interested? I got positive responses from three companies. I made my selection (Microstep UK) based on cost and a general feel that they’d be easy to work with. Despite the low order volume, my panels, precision laser-cut with mounting holes, cost just £2.60 for 1U and just £1 more for the 2U. This, remember, includes the cost of the material! These were ex-VAT prices, but basically what it amounts to is that for less than the price of a typical ready-made Eurorack module, I obtained 30 panels totalling a whopping 40U.

A key part of this step is to be really clear from the outset as to what your requirements are. I’d decided that I wanted blanks that I could immediately mount into my system if I wanted to – this meant specifying height, width, material and the location of mounting holes. For quoting purposes, just the number of holes should be sufficient. It’s really important to be clear about what you don’t know, too; in my case, I had no idea what grade of material to use or how to obtain it – being clear about this with my candidate suppliers enabled them to advise and quote appropriately.

Drawing a blank

Preparing drawings was a breeze, as I already knew all of the critical dimensions that I needed. Paul at Microstep had told me that any sketch would do as long as it contained all the dims needed to actually make the thing, so I knocked these up with a graphics package and emailed them over.

1U panel sketch   2U panel sketch

Drilling – before we start

Drills are basically dangerous, high-speed, spinning, cutting, hard, metal death machines. Humans are basically big, soft sacks of liquid. Guess which one would win in hand-to-drill combat? Yes. The drill. Every time.

Here’s another interesting fact – a piece of aluminium that a drill-bit has jammed in part-way through instantly becomes a very effective rotary machete. Your fingers are basically sausage-skins wrapped around some twigs, jelly and fluids. I think you understand what I’m saying here.

So, to fully labour the point about safety, here are some rules:

  • ALWAYS clamp the work piece securely before drilling, NEVER just hold it down with your hands
  • ALWAYS keep the drill still and stable when in use (use a drill stand if you can)
  • ALWAYS use the correct drill bit for the job
  • NEVER try to drill directly into an unprepared, unmarked surface. That bit will skate straight off, probably into a major artery
  • NEVER try to drill a massive diameter hole in one go. Bits of metal will fly everywhere and your work will probably turn out awful. Except that you won’t be able to see how awful it is because your eyes will be full of sharp, pointy bits of metal. Start small and use progressively large bits to widen the hole over several cuts
  • ALWAYS take sensible steps to protect your hands and your eyes
  • NEVER put any part of yourself near the drill bit while it’s turning
  • IF you’ve got long hair, restrain it (I use a bandanna; it works, it’s comfy and it looks awesome)
  • IF you’ve got a massively long and excellent beard, restrain it (I’m not sure how you would, because my beard isn’t yet excellent enough, but find a way anyway)
  • ALWAYS remove any jewellery from hands, wrists and around your neck
  • ALWAYS be unfailingly respectful of the ability of machines to do you harm. No, not like “Terminator”. Think “life-changing industrial or agricultural accident” instead. Less glamorous but much more permanent.

Got that? Sweet. Stick to those and you’ll come through this with exactly the same number of sticky-out bits as you started with.

In order to make the job easier and to protect my delicate, musicianly digits I invested a handful of pounds in a couple of bits of kit; a drill stand and a drill-press vice.

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I got them from eBay, they were cheap, they work fine and they make being around high-speed-rotary-murder-equipment a lot safer.

Two things to note about drill stands and vices:

  • The drill stand must be solidly fixed down to a stable surface, otherwise you’re just trading one instability for another (possibly more dangerous) one. I just screwed mine to my workbench
  • I found that the faces of my vice arrived quite rough and not brilliantly finished. Fortunately I noticed this before permanently damaging a blank. Check for rough edges on the castings and take a file to it if necessary. It took just ten minutes to get mine absolutely silky-smooth

Got all of that? Great. Let’s make some holes in some stuff!

Preparation for drilling

Before I started blasting holes into my nice, shiny aluminium, I figured it would be pretty useful to have a clear idea of what size holes I wanted to make and where they would need to be.

First of all, I needed to know what size holes to drill. This is where a drill gauge comes in really handy.

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Taking one of each of the components that I wanted to mount and removing any nuts and washers, I fed each component into the drill gauge until I found the perfect sized hole for it. I figured that “slightly roomy” is OK – it’s better to have a tiny bit of slack to work with rather than end up with holes that are too tight, right? I took a note of the hole diameter that’s required for each type of component.

Next, I made a 1:1 scale (that is, actual size) drawing of where each hole was going to be on the panel. I did this with drawing software and printer, but a pencil, ruler and paper works just as well. I made sure I had the exact centre of each hole clearly marked, together with its diameter. Here’s one of my drawings:Moog-Filter-Cutting-GuideNext thing to do: transfer the centre point of each hole onto the metal. For this I used a centre punch. I bought an automatic one for a couple of quid from eBay – but a good old-fashioned-hit-it-with-a-hammer one will do just fine.

I used a bit of masking tape to secure my cutting guide to the front face of my work piece. Generally, I choose the face with fewest scratches/tooling marks and the cleanest edges to be the front face.

And then, by placing the punch on the centre of each hole and just pressing, it punched a neat dimple into the metal, exactly where I wanted. This dimple is important because it gives the point of the drill-bit something to sit within – which prevents the bit from just skating off across the metal.

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With all of the hole centres marked, I removed the paper guide from the piece. I kept it to one side, though, as it had all of my diameters marked on it and I’d need that to refer to in the next step.

Which was…

Drilling

Drilling the holes is the most time-consuming and tedious part of the whole job. It involves repeating the same, simple actions over and over and over again. Which is why it’s dangerous, so don’t do this tired, don’t do this distracted, don’t do this whilst even mildly annoyed about something. You need to be able to give the drill, the work and the process your complete attention, else it’ll go wrong. Possibly involving loss-of-digits-levels of wrong.

I use HSS drill bits, I’ve found that I get a better and cleaner result from them. This does, however, mean a lot of steps in the drilling process. I tried using “step” or “cone” bits, but I found that they kept getting clogged with swarf and just weren’t giving me the result I wanted. So, slow and steady, lots of drilling.

First task was to put a pilot hole through all of the marked centres. I took an educated guess at what diameter this should be, assuming that it needed to be smaller than the smallest hole that I wanted to drill.

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My smallest hole is 4mm, so I went for a 3mm pilot hole. This is probably a good time to introduce my Mantra of Drilling:

  • If it’s not off, switch the drill off
  • Clamp the piece into the vice
  • Position the clamped piece under the drill bit
  • Switch the drill on
  • Gently introduce the drill bit to the centre mark, like the softest whisper of a kiss
  • Apply gentle but firm pressure. Like a … slightly hungrier kiss?
  • Keep going until the drill bit Breaks On Through To The Other Side (the “kiss” analogy broke down at this point, so I enlisted The Doors instead)
  • Carefully back the drill out of the hole
  • Turn the drill off
  • Wait until the drill has fully stopped
  • Remove the clamped piece from under the drill
  • Unclamp the piece
  • Flip it over. Use a flat file to remove any scruffy bits on the back of the piece (so that it’ll lie flat when you clamp it again)
  • Clear any swarf from the vice, drill bit and drilling area
  • Repeat

Occasionally there’s a break to the monotony to change the drill bit for a larger one. Sometimes there’s a magical moment when two (or even… gasp… three) adjacent holes can be drilled without having to remove the piece from the vice. Joy!

The bottom line of this bit is that it’s tedious but quite Zen, in that you have to be sufficiently in the moment to know what you’re doing, stay safe and stop drilling when your hole is the right size.

To keep the number of tooling changes to a minimum I work up through the drill bit sizes progressively. Assume that we have some M4 PCB mounts, a couple of switches, a couple of LEDs, some pots and some 1/4″ jacks on a panel; that’s a 3mm pilot hole, 4mm holes for the M4 bolts, 6mm for the switches, 6.5mm for the LEDs, 7mm for the pots and 9mm for the jacks. I’d go at it like this:

  • Drill all the holes with a 3mm bit
  • Widen every hole to 4mm
  • Widen every hole EXCEPT THE ONES THAT ARE MEANT TO STAY AT 4mm to 6mm
  • Widen every hole EXCEPT THE ONES THAT ARE MEANT TO STAY AT 6mm to 6.5mm
  • Widen every hole EXCEPT THE ONES THAT ARE MEANT TO STAY AT 6.5mm to 7mm
  • Widen every hole EXCEPT THE ONES THAT ARE MEANT TO STAY AT 7mm to 9mm

2mm is the biggest jump I’d do, especially in the 7mm upwards range – that’s actually quite a lot of metal to remove.

I seem to get best results running the drill quite slowly and keeping the pressure on the drill bit moderate. I’ve noticed that if I’m too light with the drill it’ll tend to chatter a bit and I end up with holes that are slightly triangular in shape. Getting the weight on the bit right is definitely key to how tidily the hole finishes.

Although this is very long-winded, once I’m in a rhythm with it the time actually flies; after just a couple of rounds of practice I can drill and finish a 2U panel in under an hour.

When all of the drilling is done, it’s time to …

Clean Up

At this stage I got a bit concerned that my panel was steadily looking shabbier. I had rings of metal sticking out at the front and the back looked like it had been under a bus.

It turned out that this was OK, and it would actually look even worse before it started to look better.

So, first step to cleaning the piece up was to run the flat file all over the back again and remove any remaining metal burrs from around the holes. As the back won’t be seen I just made peace with the fact that it looked pretty dreadful and got on with it.

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Then, flipping the piece over, I used just the very nose of the file to do the same on the front. This left some really shabby-looking areas, but as there was a lot less metal to remove it was pretty straightforward and all of the damage was limited to areas that I knew would end up ultimately being covered up by my control panel markings anyway.

I did notice, however, that some of the burrs folded into the holes during this process so I dug out my set of one-of-each-component again and tested that everything would fit where it should. No surprise, some of them didn’t. This was solved by easing the hole with a small, round file.

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The final steps to cleaning up were to run the flat file along any sharp edges, and gently smooth away the one bit of metal that the laser had left on one short edge of the piece; by the look of it, this was where the laser had started and stopped its cut.

At this point I gave the piece a good wash with lots of running water and a microfiber cloth, then dried it with a clean cloth.

Finishing

There are as many ways to finish metal as there are … actually, I don’t know. But there are lots. Being fundamentally quite lazy, I wanted something that would

  • Look nice
  • Could be achieved relatively easily with a minimum of tools and skill
  • Could be achieved consistently on separate occasions
  • Would be not too reflective (because, stage lights. I need to be able to see my synth to use it)
  • Would be durable and resistant to fingerprints

After doing tons of research, I settled on brushing as the solution. I could cut the surface with a stiff wire brush then lacquer over it to protect it.

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I spent a good hour or two trying to think of increasingly elaborate ways to keep my fingers out of the way and the piece still while brushing it before it occurred to me that “hey – this thing is full of holes”. Two minutes later I had it firmly screwed down to my workbench, problem solved.

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Brushing is easy. Put a bit of pressure on the brush and stroke it away from you for the full length of both the brush and the piece (that is, start with the brush fully off the piece, then brush in a dead straight line. Stop when the brush is once again fully off the piece.

And… repeat.

This is one of those cases of “just keep going until it looks how you want it to look”. I ended up with the metal going almost matt white in colour and texture.

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Back to the sink, another wash (this time with some dish detergent to remove any remaining finger grease), a thorough rinse, towel dry and then air dry on a sunny windowsill for an hour.

Done, and ready for…

Lacquer

I bought a can of gloss lacquer. I made a three-sided box out of some Correx (leftovers from that time I lined my lighting case) to use as a spraying booth. I followed the directions on the can and applied two coats.

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The result, after 24 hours of drying was… well, actually, it was quite, quite lovely. Silky, flat, cool-to-the-touch, brushed aluminium. Pretty consistent too, across the first half-a-dozen pieces that I’ve made. Result.

As with absolutely everything else in this process: don’t rush. Read the instructions. Understand first, do second.

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Wow, this really is getting pretty god-damn Zen.

Panel labels

I wanted to reproduce the screen-printed white-on-black look of the classic Moog modules for my modular synth. In my prototypes, I’d simply used inkjet-printed paper, fixed to the panel with double-sided tape. Surprisingly, this actually looked pretty good, but there were issues – the tape didn’t hold particularly well and plain, budget printer paper isn’t exactly durable. However, the ease of production and the low-tech, low-skill nature of this process was very appealing, so I set out to see if I could improve on the result without changing the basic approach or tools (Photoshop, laptop, printer).

I found a UK company that stock specialist inkjet papers – Photo Paper Direct – who have an inkjet-printable, self-adhesive, vinyl paper in their range. Additionally, they have a range of spray lacquers that increase the durability of the print. I ordered a pack of paper and a can of lacquer.

I did a test print, stuck it to a finished panel and left it in direct sunlight on my conservatory windowsill. After 3 very sunny days at temperatures in excess of 35 centigrade (the conservatory gets very warm even on mild days), the paper hadn’t peeled and the ink was as black as when I printed it. The texture of the lacquer (I went for the “satin” finish) was very close to screenprint and the paper was thin enough that, unless you looked very closely, it was hard to tell that it was stuck, rather than printed, onto the panel. So far so good.

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It took me a couple of attempts with actual finished modules to master cutting out the vinyl print in such a way that I could hold it by the scrap edges and still have guide marks for aligning it onto the panel, but I eventually got this sorted. The photos show how this works.

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One thing worth mentioning is to include “bleed” in the artwork – that is, continue to print black beyond the edge of the panel. That way, when the vinyl is cut to the size of the panel, you’re guaranteed that the black runs right to the edge of the piece.

All that was left to do after this was to use a sharp craft knife (the newer and sharper the blade the better) to trim out the holes.

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I’d expected getting a good-looking, hard-wearing print to be the most difficult part of this whole job. Instead, it’s turned out to be almost trivially easy.

Final assembly

Last part of the job – add the panel components and mount the PCB.

This needed to be done with care – it’d be a dreadful shame to maul the freshly-made-and-printed panel so I was cautious to hold it by the edges. Fortunately, that Moog aesthetic of having the aluminium show through at the edges gives a nice area to handle the panel by. At this point I really appreciated the lacquer on the aluminium as it picked up no fingerprints or handling marks at all. 

Having already test-fit everything earlier in the process, fitting components was a breeze. The only thing to be cautious about was ensuring that none of the nuts “pulled” the vinyl as they were tightened. This wasn’t an issue for the larger parts or parts that come with a washer, but for a couple of the switches and my PCB mounting screws this was tricky to achieve. I’ve discovered that it’s much better to hold the nut still and turn the component until it’s tight than to do it the other way around.

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I’ve found that the Fresnel-style LED clips that I use don’t sit tight in their holes so I’ve had to use a dab of hot glue from the glue-gun to just secure them in place. Not a big deal, and entirely reversible if I ever need it to be.

For PCB mounting, I use either M4 brass pillars (where the panel is wide enough to accommodate the PCB “flat”) or, where the PCB has to be mounted at right-angles, old Meccano No 12 brackets bought from eBay (much cheaper than alternatives!) do the job brilliantly!

Here’s a finished YuSynth ADSR module, made using the process described above.

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Conclusions and what’s next?

For the moment, I’m pretty happy with the results I’m getting from my panels. There are a couple of things I’d like to improve on (alignment of the panel print and the cut holes isn’t quite precise enough yet, for example) but I think they’ll mostly turn out to be down to practise and patience. Time will tell, too, whether the printed vinyl is robust enough for the job (although I have already considered putting a further couple of coats of aluminium lacquer over the panel and print to improve this). The thing is, the vinyl is removable with a little effort so I can always re-visit these early panels later on if I feel the need to.

Overall, I think these are decent, tidy, consistent and repeatable results for low-budget, low-skill DIY – which is exactly what I set out to achieve.

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Now… I just need to get that nice, big case built

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