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Re: Anybody actually milling pcbs with shapeoko?

Posted: Thu Aug 09, 2012 9:12 pm
by jsbannis
The accuracy you get with measuring offsets would be pretty poor unless you used a ton of sample points and used a good interpolation between them. The sacrifice board is going to have surface imperfections all over that are larger than 0.002". Probably easier to use the bit Edward suggests in this post and face a square out of mdf the size of your board. I can't imagine it would take that long to take off 1/32 or so off the top to make it square to the machine if you were only doing an area the size of a small board.

Re: Anybody actually milling pcbs with shapeoko?

Posted: Fri Aug 10, 2012 6:51 am
by cvoinescu
Good interpolation is not a problem. Getting a ton of points is not a problem if the process is automated, but good point about the imperfections of the board and how to deal with them. It did not occur to me that the machine was, in a way, self-leveling. :)

I am not deterred from trying the auto-calibration-by-touch method (except temporarily, by the lack of a ShapeOko). When I do it, I will report here. PCB milling is high on my list of things to do with the ShapeOko once it arrives -- I will have to get the electronics off breadboards and into some sort of enclosure as soon as possible.

Re: Anybody actually milling pcbs with shapeoko?

Posted: Tue Oct 02, 2012 12:16 pm
by DrRob
Do you think it might work to put a rotation sensor on the cutting tool, and detect the very slight loss of rotational speed when the bit bites into the copper?

Edit: that won't help keep an accurate level while cutting across the board though. You'd have to keep raising a re-lowering the tool to recalibrate. Hmm.

Re: Anybody actually milling pcbs with shapeoko?

Posted: Tue Oct 02, 2012 5:42 pm
by cvoinescu
DrRob wrote:Edit: that won't help keep an accurate level while cutting across the board though. You'd have to keep raising a re-lowering the tool to recalibrate.
So? :)

You could even measure spindle current, which is bound to increase when it's under load. Especially easy if you have something like a 12 V DC Proxxon tool.

I'm going to try PCBs as soon as I get some spare time (which may mean a month from now...). :cry: