Wednesday, June 17, 2015

The mock-up front-panel/sub-panel

 Panel pondering

Just before the end of last year I'd started to make a mock-up front-panel and posted a picture. The idea is to have somewhere to put all the controls, wire them up properly and test things. That should clear the way for (at long last) the MIDI interface.

When I went back to it a few months ago I decided it was terrible. Cutting MDF has to be done carefully and mine was not done carefully. The drilled holes were fluffy, the board was too thick and I just wasn't happy.

At about the same time I had been thinking about having a wooden front-panel. This thought was itself prompted by returning to the idea of using the original switches and knobs.

In other words, if I use the original switches and knobs they would look best in a wooden panel. But, how would I do that? I thought about rosewood veneer, but then I started looking at laser cutting wood.

Once I started looking at this I realised there was a better way to create a mock-up front-panel.

Frikkin' lasers

A wooden front-panel

Here in the UK I found Razorlab. Their prices are reasonable so I took a design I'd already created in Front Panel Designer saved it as vector file (.svg) and then imported that to Inkscape. The design is placed in a special template provided by Razorlab which matches the size of the material. The way it works is that lines drawn in different colours either cut or line engrave or raster engrave with different strengths.

I quickly did this and sent off my design. A bit too quickly as I'd made a couple of minor mistakes, but nothing too critical. Razorlab state they will deliver in 28-days. Well, mine took over that, by a few days, but a few weekends ago I finally got the panel back.

 The first issue was that one of the holes was not completely cut.

Incomplete cut on the bottom-left

 In fact, that cut wasn't needed. The Cello Volume control should have gone there, but it's also part of the sub-panel on the row of knobs above. I had included a hole for it there and on the next picture you can see the reverse side and where that ended up.

Reverse side

As this is a mock-up it doesn't matter too much about one misplaced control, but it's a good reminder that these things should be checked carefully.

Sub or front panel?

. One thing that makes for a tidy finish is a sub panel. Basically the controls are fixed to the sub-panel and then the front-panel is fixed to sub-panel. The front-panel just has holes and no unsightly bolts and fixings.
In the original SS30 the metal sub-panels are screwed into the wood. The switches have spacers between the switch assembly and the wood to ensure that they sit just proud of the panel surfaces. The knobs' sub-panels are simply screwed into the wood and the thickness of the wood is such that when the knobs are fitted onto the pots they sit just above the surface and don't sick out too far.

In the shot above you can see that I've bolted the pots directly onto the panel. The sub-panel is still there behind but it's just held on buy the bots at the front. You can see on the pots that have knobs on they stand too far out.

But for the switches I had to screw them to something and so I decided I might as well make them sit back and be positioned more or less correctly.

Now that's done its time to wire everything up.