CNC 3018 PCB drill bit break

[A_Camera]

Quick correction there, standard 1oz/ft2 copper is 35 micron (0.035mm, not 0.35).

0.4mm is a bit aggressive, also for isolation routing I’d expect a smaller diameter cutter for any standard 0.1” or less packages. OP, start with a shallower cut.

Some of the traverses are suspicious, but i(blindly) wrote those off as OP playing with settings, looks to have moved to board reference with z at zero, all part of the learning curve. If I’ve been presumptuous then apologies to OP.

Last thing that OP needs a heads up on is that copper laminate is anything but flat. A good first stab is some form of pressure foot to hold the substrate onto the bed, but that assumes a flat and level bed… those need to be established before you’ll get any good result.

You are right, I am sorry, I left out a zero. Of course, I meant 0.035 mm for the copper layer and the milling depth I use is 0.04 mm. Never went deeper than 0.07 mm.

Yes, it is VERY important that the table is flat and levelled. I face the MDF every now and then (basically almost every time) but I don't use any double sided tape because that is making the table uneven and facing pretty pointless. I only use tape on the edges, in my opinion that's enough and better than screws or anything which pushes the edges down on far too small area because that will result in raising the centre of the PCB. I think it is better to apply holding force on all edges using tape, but of course, a vacuum table would be even better. Some people use super glue, I don't. I think super glue would work well also, but removing becomes a PITA, so I won't use that. I only buy quality PCB and so far I always found them flat enough. When I zero the cutter I try to find the lowest point on the PCB to reference to, that way even if some parts are slightly higher, the track isolation will be OK.

I made a video some years ago, in this video I mill down to 0.07 mm in two passes, but lately I mill in one pass and only to 0.04 mm depth. I the video I run the spindle at 22k rpm, which lately is 24k. I found that less tips are broken with higher rpm.



BTW, I also no longer use Eagle. I think that the free version it is too limiting. I use EasyEDA and FlatCAM today.