[woffler]

I am having a problem with a cad program that will under size a pocket .005 every time.

And i have different one that gets it right with in + or - .0001 or .0002 i guess what i am asking is this normal ? or what it drives me nut's.

So i have to add to a demension ,to get it with in tolerance , i ran ten pockets five each per program same results every time.

Any one have any idea's ?

[txcncman]

The problem is probably not your CAD. Most likely it is your CAM. That, and operator error. Sure you are not using an undersize mill? Did you measure it?

[woffler]

I believe you are right that it is the cam program, i used the same end mill to do the current test on both cam program's.

I ran five pocket's each with a new measured .25 carbide end mill, high helix 3 flute center cutting end mill.

The measurements where consistent on each set of pockets , i had noticed the discrepancy and wondered if it was just the cad program, hence the reason for the test.

I also ran a machine test to see if anything had changed there and found none .
So i thought well maybe i had made a programming error some way along ,would not be the first or last time!

I think i will try and find someone with the same software to run a test for me and see what they get.

Thank you for replying to me on this , i will continue the hunt for the problem and see if it can be nailed down on my end .

[neilw20]

CAD exact, CAM exact, now use toolwear compensation or just program the tool to be the actual size it cuts. Operator learning curve.
Next time you chuck the tool it might not run the same size, exactly.

[txcncman]

I believe you are right that it is the cam program, i used the same end mill to do the current test on both cam program's.

I ran five pocket's each with a new measured .25 carbide end mill, high helix 3 flute center cutting end mill.

The measurements where consistent on each set of pockets , i had noticed the discrepancy and wondered if it was just the cad program, hence the reason for the test.

I also ran a machine test to see if anything had changed there and found none .
So i thought well maybe i had made a programming error some way along ,would not be the first or last time!

I think i will try and find someone with the same software to run a test for me and see what they get.

Thank you for replying to me on this , i will continue the hunt for the problem and see if it can be nailed down on my end .

Well, it still could possibly be CAD. What is your default accuracy setting? If you have it set for 2 decimal places, this could be your problem (round off error). Increase it to 3 or 4 decimal places. In your CAD, actually measure and dimension some discrepant features. Say, draw a 5/8" diameter circle and then dimension it and see if it is actually 0.625" or if it comes out to 0.63".

[woffler]

ThankYou TXcnc man ,i am going to try your suggestions this am and i will report back .

[BurrMan]

Post sample geometry and some info on your CAD and CAM package. I have an idea that might help.