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Post by Debbiebayneomeara »

When calculating the rough machining tool path I get a message that comes up - The allowance left on is greater than 20% of the tool diameter. What do I change?

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Re: Calculating

Post by cabnet636 »

the machining allowance at the tool path cut it in 1/2 and try again

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Re: Calculating

Post by crchisholm »

tried that...didn't work. Can you explain exactly what this message is telling me and what I should know to fix it?

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Re: Calculating

Post by highpockets »

In the roughing toolpath change the "Machining Allowance" to zero and try recalculating. The Machining Allowance can not be over 20% of the selected tool diameter. So if you choose a 1/8" ball nose for roughing your Machining Allowance has to be .025 or less.
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Re: Calculating

Post by adze_cnc »


The second half of this warning is a clue to the answer for your and the original (from 7.5 years ago!) poster's question. The amount of material left by the roughing bit might cause finishing bit to break, etc.

If you are certain that your finishing tool can handle cutting the amount of material left after roughing you can safely ignore this warning. If not, change the "Machining Allowance" to be equal to or less than 20% of the bit diameter. e.g. roughing tool 0.375"; machining allowance 0.0075".

If I'm roughing out EPS foam with a 3/8" bit I might leave 1/8" or more for the finishing ball end bit to clean up. The foam is so "soft" that a 1/4" or even 1/8" ball end bit will have no problems shearing it off.

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