Re: Helical milling drill holes with endmill #pcbgcode #drill #helical

Harvey White

I think that the direction depends on the stage of the operation.

The tolerances depend on the cutting tool, the rigidity of the setup (unimat NOT rigid, Seig X2 much better, Bridgeport no problem), and the material being cut (not only hardness but how smoothly it cuts).

Were this metal machining (and cutting a pocket in, say, aluminum, T6063), I would use conventional milling to within a certain distance, as a guess, I'd say about 25 thousandths.  I'd switch to climb milling and take off  no more than 5 thousandths each pass.

Now, PC boards?  Lots less experience.  Assuming a 1/16th board, and a 1/8 carbide roughing tool, you don't want to take off more than 1/4 of the width of the bit (IMHO), so about 32 thousandths per cut, then go down to the usual 5 thousandths or so (rather conservative perhaps) for the final passes.

The numbers are guesses, and I'd want to refine them under actual practice, but there they are.  Someone with more experience would be able to provide more accuracy.


On 8/11/2022 2:24 PM, John Blanchard wrote:
I stand corrected. Thank you for the clarification. The picture makes it much more clear.

I got the direction wrong so I guess G02 is preferred?

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