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Re: Need PCB Milling Settings

Posted: Sat May 17, 2014 3:27 am
by scott216
I did another test which came out nice. I used a 0.0118" end mill at 3 IPM feed rate and WD40. DW660 spins at 30k RPM. Not sure of the depth in the photo below because my PCB was not flat. Some parts milled great like in the photo, other's didn't mill at all and would need another pass. In the photo I think it's about 0.004" deep. I use PCB-GCODE to generate the gcode from Cadsoft Eagle. The board did not need any sanding, there were no burrs. I cancelled the job before it was done, I wanted to restart at a little lower depth. Unfortunately I found out when you cancel you lose your workpiece coordinates.
PCB Test 4.jpg
PCB Test 4.jpg (134.79 KiB) Viewed 2267 times

Re: Need PCB Milling Settings

Posted: Sat May 17, 2014 2:30 pm
by cvoinescu
That looks very clean indeed. Depending on your host software, it's also possible to stop a job and preserve coordinates -- GRBL supports that (the feed hold button, and there's also a control character that does the same thing).

Re: Need PCB Milling Settings

Posted: Sun May 18, 2014 4:01 am
by scott216
I ran the whole board today. I just did a single pass because I didn't want to wait too long. I need to do it again with the isolation passes enabled so there is more copper removed between the traces. I re-flattened my masonite and I used Scotch double stick tape - the thin stuff. I was using double stick masking tape. This made a big difference in flatness. I taped my board down and ran a dial indicator over it and it was dead flat. My setting were: 0.0118" bit diameter (but in pcb-gcode I set it to 0.015"), 4 IPM Feed, 0.004" deep, 30k RPM and WD40. The board came out really nice. I did give it a very light sanding.
PCB no-iso test.jpg
PCB no-iso test.jpg (461.55 KiB) Viewed 2232 times
PCB Test 6.jpg
PCB Test 6.jpg (152.9 KiB) Viewed 2232 times
These holes are supposed to be like this - not centered in pad.
PCB Test 5.jpg
PCB Test 5.jpg (111.16 KiB) Viewed 2232 times

Re: Need PCB Milling Settings

Posted: Sun May 18, 2014 9:20 pm
by ThinkItShapeIt
Very nice work! I am impressed that you were able to cut the entire etch in a single pass. I think I need to pickup some of this thin scotch double sided tape. Please keep posting your progress.

Is the trace on the top DIP6 supposed to connect to two pins?

Re: Need PCB Milling Settings

Posted: Sun May 18, 2014 10:45 pm
by scott216
ThinkItShapeIt wrote: Is the trace on the top DIP6 supposed to connect to two pins?
No, but one pin in not used. I've since fixed it anyway.

Re: Need PCB Milling Settings

Posted: Sat May 31, 2014 3:04 pm
by alexig
Looking good! I'm going to order the .0118 two flute end-mill and give that a try, it looks like it'll work based on your results.

Re: Need PCB Milling Settings

Posted: Sat May 31, 2014 3:08 pm
by scott216
alexig wrote:Looking good! I'm going to order the .0118 two flute end-mill and give that a try, it looks like it'll work based on your results.
I've done a couple more boards and I'm happy with the 0.0118 bit. I just received 10 more bits on ebay from drillman1. He ships from the US, so it only takes a couple days.

http://cgi.ebay.com/ws/eBayISAPI.dll?Vi ... 0909768195

Re: Need PCB Milling Settings

Posted: Sun Jun 01, 2014 3:49 am
by alexig
How many boards do you think the 0.0118 bits will last? They are quite pricey compared to the 0.1mm 10degree V-bits that I bought from ebay, though I'm on my third bit at the moment.

Re: Need PCB Milling Settings

Posted: Sun Jun 01, 2014 7:28 pm
by scott216
alexig wrote:How many boards do you think the 0.0118 bits will last? They are quite pricey compared to the 0.1mm 10degree V-bits that I bought from ebay, though I'm on my third bit at the moment.
Personally I have no idea, I'm new to this. Since board layouts can vary a lot, you really want know how many linear inches you can mill. I've read that different feed settings can impact the mill life. I've been using WD40 with my PCBs, I'm sure that helps. I assume the FR4 PCB (fiberglass base) will wear out a bit a lot faster then the FR1 (phenolic base) boards. Because I've broken a few bits going up the PCB milling learning curve, I haven't milled very much with any one particular bit. I did try those 0.1mm bits you have and I found out my setup wasn't level enough. I think the pcb needs to be really really flat and level for those to work well.

Re: Need PCB Milling Settings

Posted: Mon Jun 02, 2014 8:15 am
by zerblatt007
This is nice!
So 0.3mm is the usable dimension?
0.4mm is to much?

Do you drill the holes with the same bit?