You can find these encoders at cheap prices on ebay. They have a 6mm shaft and the housing features a little bump in it that should be matched by a hole in the case and it serves to prevent the housing from rotating when you turn the knob. You can see the little bump at the bottom of the photograph.
The shaft is a 6mm diameter D-type. I wanted a nice looking knob for it so I selected a brushed aluminium design available for £2.49 from Maplin on the high street, order code YR65V. The hole in the knob at the bottom houses the grub screw that tightens up against the flat part of the D-shaped shaft. The next part will be the cooling fan.
I selected a 40mm Gelid Silent 4 that would be mounted directly adjacent to the heatsink attached to the triac. I created cut-outs that exactly match the frame of the Gelid. It would certainly be possible to use a different fan than the Gelid because the screw holes are in a standard position but the air vent cut-outs will probably not line up perfectly.
That’s all for the fixtures and fittings, now all I need to do is to place holes in the base for mounting the board itself as well as smaller holes that I’ll use for fastening down wires that need to run from the board to the edge of the case.
Here’s the final design.
To test the design I printed it out and cut out the panel sides. I could then stand my board on the base to make sure the screw holes line up as well as offering up the sides to ensure that the cut outs were where they’re supposed to be. After a few revisions it all looked good so it was time to upload to Razorlab and get the making under way.
The total price including tax and shipping was just over £40 and that includes the extra design that I squeezed into the template. Razorlab claim a 28-day turnaround which seems like rather a long time to me but they are clear about that upfront. My order took the full 28 days and then a bit more because I made a mistake and strayed into the margins of the template. Hazim from Razorlab emailed me and I shuffled some parts around to come within the margins and the making process was unblocked.
