Embedded Files
Desktop CNC machines all look and setup differently and may even come with their own software. Here we are using a Genmitsu 3018 hobbyist desktop CNC router. Some of these routers come with offline modules for manual control, ER 11 collets for easy and secure tool changes, Z probes to set Z zero, limit switches and E stops. You will need to read your router manual, maybe watch some training videos, and do some simple trial projects to learn all the ins and outs of your machine.
HOLD DOWN
Make or find a way to hold down copper clad board flat on the CNC bed. The system shown above is not too bad but tightening the wing nuts can cause the board to bow up in the middle. The circuit on the right, below, shows what happens if the board is not flat.
BITS
In some of the articles on this subject the author uses V bits. I found that the V bits tore the edges on the cuts in a single pass. V bits would require 3 passes to clean up the edges.
I had better luck with a 0.5 mm end mill. I broke the bit I had so I ordered some more but the new ones break like twigs. A 1mm bit makes wide cuts and enlarges the board but for learning exercises a larger bit will be harder to break. In the photo below you can see the tearing at the edges when using a V bit. With any bit you need to work with Flatcam to make sure the traces are wide enough and do not tear out (see 0.5 mm end mill below). The photo shows 3 successful circuits using a 1mm end mill at varying depths. Sometimes 0.001 is not enough because the copper cladding thickness can also vary.
SAFETY
The bit is cutting through copper and fibreglass creating dust. I recommend a mask as well as good safety glasses with side shields. Vacuum the dust up before it spreads. After cutting polish the board with 400 grit sandpaper to clean off any splinters and get the board ready for soldering.
CANDLE
The Candle software is free and works well with the grbl firmware on the Genmitsu routers.
ZERO
Zero X and Y so as to make good use of your copper clad board. Make sure the bit will not run into any of your hold down clamps during cutting.
ZERO Z METHOD (no Z probe)
Move the cutter to the middle of the board. Use jog to lower the bit to within 10 steps. Change the Step value to 1 and move the bit to within 1 or 2 steps. Change the step to 0.1. Place a strip of paper under the bit. Jog down in 0.1 steps while shuffling the paper back and forth. When the bit catches the paper jog once more (0.1). Now the paper should rip if you pull. The end of the cutter is at the top of the copper. Zero Z and jog back out to release the paper.
SAFETY
Never walk away from the router while it is cutting. Something could be wrong with the G code causing a crash or fault or your board might vibrate loose. Keep Candle on top of everything else on your computer and know how to pause or E stop.
Place the router on a rubber mat and then clamp the router to the table to reduce vibration and stop the machine from creeping. Only power up the router when you are ready to cut. Power down the router before you reach in to unclamp your work.
Page updated
Report abuse