MadManMoe's PCB Milling attempts

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madmanmoe
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MadManMoe's PCB Milling attempts

Post by madmanmoe » Fri Mar 15, 2013 12:50 am

I know that a few people here have done this and I'm not really adding much, but I was proud of what I'd made so.

Milling PCBs was top on my list of things to try. So I just bought some copper clad board drew up a design (not in Eagle, for such a simple piece it would just have slowed me down)
and had a go with a cheap HSS V-bit that came with my Dremel.
You can see that the results (left board) were very rough, but I still had a perfectly functioning board.

Image

My second attempt used a 0.8mm ball nose and produced a much neater board. I was really happy with the results, until my chinese V-bits arrived and I was able to produce a super clean board with 0.2mm isolations.

Image

The rest of the tooling was just 1mm and 3mm 2 flute endmills and a 0.8mm drill bit in a dremel multi-chuck. I'm going to invest in a 0.8mm pcb drill bit (I've figured out this is adequate for most through hole components leads)


If anyone wants to know what the board is from or see the populated board it's in this blog post (near the end)
or this gif probably gets the point across.

Anyone who's not sure about trying this, have a go it's really easy.
Just get some copper clad board draw something up in inkscape and go, as I said yo can use whatever tooling you have (until proper bits arrive, at 5 bits for £4, you can't lose)


A couple of things I've learnt so far:

- Z control is very important, just 0.05mm surface difference will change the width of your traces, if they etch at all.
- I found it best to mill a flat surface and them just use masking tape to secure my board to the surface. Too much tension on the edges can bow the board and double sided tape means the board won't lie flat.
- Don'y buy generic fibreglass board, this will blunt your tools faster, try to find some FR1, paper based boards.
- When drawing isolation paths, overshoot the edges, even a hair of copper left where it shouldn't can short out your circuit.
- Also the board I bought had a slightly matt protective coating on it, it soldered just fine so if you want your board to stay nice and shiny and not oxidise resist the urge to polish it up with wire wool.
You can see the difference in my first image.

- This might just be an odd bug on MakerCam, but I have to set my drill distances about 10% deeper than I my profile cuts to get them to drill clean through*.


* For example the large holes and the profile cut are both done with a 3mm bit. In makercam i set both to 1.7mm deep (material measures 1.6) I run the file and the board cuts out perfectly, but there's still about 0.4mm of material at the bottom of the holes. The only thing I can think is that I'm getting accumulated backlash from using the 'peck' feature when drilling. (come to think of it this seems most likely, the other day I found that the bolts had shaken loose on my delrin nut).
MadManMoe's Blog
eShapeoko #23 Dual Y, Dual X, Dremel 4000, Pololu a4988 steppers run from LinuxCNC

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