As part of the recent BuildBrighton MIDI workshop, we had to produce about twenty homebrew PCBs. The print and etching part was easy, but what took ages was drilling all the holes for the through-hole components.
- If buying all new components, not more than £50 on the entire build (just think about it, a cnc based device for under £50!)
- If using salvaged hardware (stepper motors from old printers, for example) not more than £20 total build cost
- As we’re building a small machine, the footprint of the device, when put away, should not exceed A4 size (210x297mm)
- But it’d be useless if it could only drill tiny pcbs, so it has to be able to drill up to half eurocard sized boards (100x80mm)
- Any bought components should be accessible to everyone and you should reasonably expect to be able to purchase the same components from the same, or alternative suppliers 12 months from now (so you can’t win a job lot of motors from some bloke off ebay and put cost of materials down as 50p)
- Overseas suppliers can be used to keep costs down, as their price per unit is often much less than UK suppliers.
- The device is to be platform independent – it can use any microcontroller and any software can be used to control the machine, including homemade software/drivers.
- It has only to work on any one platform, not all
- For accuracy, the drilling machine should be able to drill a 1mm hole in a max-sized 2mm pad and leave a complete copper ring intact around the hole
- For building materials, assume a price for acrylic sheets as £1 per mm thickness, per A4 sheet
- Cheaper alternatives (such as mdf or laser ply) can be used instead of acrylic for the chassis if required
- Trivial components and the cost of pcb etching, running a laser cutter etc and consumables will not be used to calculate total build cost
- The price for delivery of all components bought online will be included in the final cost
For our build, we’re going for cheap AND small.
Most other people have concentrated on one or the other. We’re more than willing to sacrifice accuracy for cost, or cost for size, or size for comedy value. As always, sporadic updates, in-between other projects, will get posted here as the build develops…..