Mechanical construction

A large part of the work in building a modular synthesizer is in the mechanics.This is also where many home-built instruments fall short of the commercial ones. I wanted my synthesizer to look as good as a commercial one, or hopefully even better.
Mechanics isn't just looks, of course. It must also be rugged enough, to withstand portable use. It should also be lightweight and compact, for the same reason.

Right now I have a temporary 19" rack case, that I built years ago. It takes two rows of modules, which won't be enough for all the planned modules. I will make a larger, portable case but the design isn't finalized yet.

The mechanical construction of the individual modules deserves some thought too. All my modules are based on a 1 mm thick brass front panel. You might think 1 mm is too thin, but I use 1 x 10 mm strips to brace the panels. A huge advantage with brass is that it can easily be soldered to. So I just solder strips to the back of the panel, when required.

This is the front panel for the VCF module.

So although brass is heavier than aluminum, my panels are probably the same weight as say 3 mm aluminum. And they are at least as strong.
The main advantage with the brass construction, however, is that I can solder studs for the circuit boards and pots etc. directly to the panel. This simplifes construction tremendously. Brass is also a nice material to drill, saw, file, tap, mill etc.

Here we see the back of the panel, with all mounting studs and brackets soldered.

Potentiometers and toggle switches are mounted on 12 x 4 mm brass U-beams, screwed to the back of the panels using threaded studs. The U-beams are oriented vertically and therefore usually hold four pots or switches, firmly secured using their supplied hardware. This way, the nuts and washers are hidden behind the panel.

Here some of the components are mounted. Note the U-beams that hold the potentionmeters.

 

Here the circuit board is in place. There are still some parts missing on it.

The completed module, with all wiring in place.

Front panel lettering

The panels are designed in Corel Draw and printed on HP Premium inkjet paper, using a Hewlett Packard Deskjet 720C colour printer. The printout is laminated om both sides with clear self-adhesive plastic that has a satin finish. It is then glued to the panel. This way I get a scratch and water resistant surface and any colour I want. The panels' base colour is Powder blue.
These panels probably aren't tough enough for everyday road use. The paper can peel at the edges, and especially at the corners, if you're not careful. To prevent this I apply a drop of cyano-acrylate glue at each corner. The glue sucks into the paper and hardens it. Unfortunately it discolors the paper slightly, otherwise I would do it around the entire perimeter. The discoloration is only visible at the lower corners, as the dark blue bar at the top hides it.

The VCF module with printed panel, as described above.