Gallery, Projects and General > How do I??
PCB pad cutter
vtsteam:
Why low rpm?
Also, are you clamping the board down?
vtsteam:
Pretty hard to tell what shape those teeth are or the angles in that photo. Looks like there's no clearance and finish is rough.
Try forming the teeth with a triangular file, smoothing the ID with a round file, and 1500 rpm. Tooth depth only needs to be a little more than copper thickness. Try 5 degrees end clearance.
Mike K:
Low RPM so that I could just remove the copper without chewing down through the board in the blink of an eye. Didn't need to clamp it down, the cutter didn't grab at all.
Mike K:
I'll try to get a better picture; the lighting in that photo is terrible.
The teeth have no front rake and just a little clearance, probably a couple degrees. Finish isn't rough, but not great. I stoned the OD edge, diamond honed the top of the teeth briefly, and didn't have anything to clean up the ID edge.
vtsteam:
--- Quote from: Mike K on January 07, 2021, 10:54:02 PM ---Low RPM so that I could just remove the copper without chewing down through the board in the blink of an eye. Didn't need to clamp it down, the cutter didn't grab at all.
--- End quote ---
From the appearance of the board, looks like it wandered one attempt, then grabbed the copper foil in the others, indicating feed too fast for the rpm and or board moving. Set a depth stop if over drilling is a problem, or add a collar as the user did in the post referenced earlier. 1500 rpm would be 100 sfpm on .25" which would be right for copper.
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