Panel/Enclosure Design and Materials

#1

Every couple of years I get an itch I need to scratch, and that’s building a funny/strange Lunetta style synthesizer. I built my original system between 2013-2017 but eventually disassembled it. My original build used acrylic laser cut panels. This proved good and bad. Good: accurate, no drilling, etch control labels/designs directly to panel. Bad: Expensive, not readily available, acrylic brittle not suitable for hand drilling. I used mostly perf for the circuit boards, which again cause problems down the line with old cold-solder joints I didn’t spot when I was first putting it together.

I eventually disassembled it with the idea, I’d revisit the project in the future when my building skills had increased. And now in 2019, I’ve started making plans to work on it again.

I’ve experimented with a couple different panels materials. Metal (aluminum) panels “feel” the best, imo. sturdy, dont have to worry about the material degrading or chipping when attaching components. I got a slew of blanks cut at metal-supermarkets that I then hand drilled. I highly recommend a “stepped” drill bit (https://www.amazon.ca/…/ref=lp_7205619…/145-7124568-7205504…) if you are going this route. It helps enormously, and you don’t have to switch a million little drill bits back and forth. Drill press is necessary as well, especially if you are using standard vector rails. the hardest part is drilling out the mounting holes. What I usually do is drill three (M3) holes close together then with a rasp grind it down to a roughly oblong circle shape.

For designs I used this aluminum etching method https://diy-guitar-effects.tumblr.com/etching it works quite well. One tip (can be applied for other things) transferring images to aluminum, you need a particular kind of paper. I found that magazine paper (what you’d find in an Ikea catalogue) works best. Just be careful if you attempt this method, it isn’t mentioned in the guide explicitly, but always where a respirator and work in a well ventilated area when working with caustic soda.

The obvious downside of metal panels, is the sheer amount of work, and tools required to make one. grinding holes for the panel mounting takes forever, and aluminum etching generates a ton of nasty chemical waste that’s not easily disposed of. Maybe some work could be reduced if a screen print, or spray paint design was used instead.

I’ve experimented with 3D printed panels in the past but always felt them a bit lacking. Maybe it’s from working with printers all day, but 3D Printed panels feel a bit cheap and flimsy to me. They can be quite accurate, if you get the tolerances just right. But again, big downside is you need access to the tech for this to even be a viable option.

PCB panels are another material I’ve tried. The best, but also most expensive option is getting them fabricated. Especially if you choose a thicker density board this can be quite nice. You can add holes, designs, different material finishes simply. The big downside, at least for the kind of DIY I am attempting, is that there isn’t a lot of room to improvise.

I’ve tried cutting panels from bare FR1 boards, but that has proved pretty imprecise. Readily available boards, the kind I find in DIY tech shops, also tends to be pretty thin flimsy stuff. I’ve only seen the thicker (same kind used in bug brand modules) PCB material available directly from the manufacturer.

Will Schorre wrote this interesting post about creating fast prototypes with FR1 board and a linoleum cutter. components are soldered up dead bug style with enamelled copper wire http://lorre-mill.com/2018/02/02/Prototype-techniqe.html?fbclid=IwAR3ru5SGwxy3KlfVzDX5rJg93LXyptXdN6xF404uYfLFoQblEIqqoTWfSMQ

There’s also Peter B’s methods as well using wood and embedded circuit boards, but again he uses a personal CNC machine, so access could be a problem for most.

One technique that I think is interesting are stompbox synths. Like the Grackler, which looks like it’s built into a 1590dd. I think it’s cool, these ready made enclosures. Hammond boxes are easily drilled by hand too. Downside for me is price per-unit, and space. Bunch of synth boxes spread out all over a table takes up much more than modules built into a rack. Probably require longer cables, and some kind of distributed power supply design.

The last material I have looked at are pre-cut HDPE sheets. This is the same material used in Lorre-Mill synths. It’s a kind of tacky plastic material that’s less brittle than acrylic or plexiglass. It can be milled easily by hand with a drill press or electric handheld drill. Manufacturers offer it in a wide variety of colours and sizes, but most I’ve seen are semi-industrial outlets so you might have to do a large minimum order. It’s a material that bears further investigation!

Curious to know if there are any techniques out there I might have missed!!

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#2

I think you’ve hit on most of the approaches to this problem.

If you have access to a DIY Hackerspace/Makerspace then laser cutting acrylic wood, or other materials can also be an option.

I recently had some aluminum panels laser-cut by a shop in portland. It’s a $75 minimum order, but that’s not really too much to meet if you’re getting a few panels made.

The only issue with laser-cut aluminum is that it’s “unfinshed” and depending on the thickness, the edges are sharp/rough with left-over material. 1/16th in panels were mostly OK, but needed a touch of sanding. 1/8in really needed edge cleanup.

There’s also some various ways to laser-etch aluminum and other materials if you’re going that stompbox route.

FWIW - the etching process you mention (using caustic NaOH/Lye) is not really toxic in terms of chemical waste. The resulting solution is then NaOH and Aluminium hydroxide. NaOH is the primary ingredient in most drain cleaners - so this is dumped down bathroom pipes all over. More info here

EDIT - Ha! I didn’t even notice your username when I replied. The 16n panels you got were done with laser + scrubbing + NaOH finish + clear coat. :slight_smile: (but still a fair bit of work)

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#3

I’ve had great luck with panels I’ve had made through Front Panel Express. They’re quite expensive in small numbers, however. For example, a 1.5mm black aluminum panel with engraved text for BitBox was about $70. That said, they have a lot of material choices/flexibility and their design software is a breeze to use. I’m not affiliated with them in any way… it’s just what I’ve used.

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#4

Yes I have one of your 16n panels. It turned out beautifully the finish on them was excellent.

Good to know about waste disposal of Lye, figured without knowing any better, better to err on the side of caution. There are environmental days that I bring stored up chemical waste, from ferric chloride that I use in PCB etching. I rarely come back to etching techniques recently, just with the amount of prep and labour involved

This is a pedal I etched following the method above. I find using a coat of black enamel spray paint then sanding it down gives the etch more depth. It takes a real balance of timing not to over etch and lose detail. Sanding down to reveal the high spots after the coat of enamel paint can be a pain in the ass sometimes

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#5

A bunch of the PCB fab houses offer aluminum as a substrate these days. I haven’t tried it, but it could be a potential for a nice in between of a FR4 PCB panel & a full on metal panel from FPE.

Looks like seeedstudio’s aluminum option is about $27 for Qty.10 for the aluminum with all default settings for a 6HP panel

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