cmm probe "compensation"

[kkominiarek]

Can CMM's programs be adjusted with probe compenstion? (x-y-z or any combination of the axis')

 

This would be similar to cutter compensation on a cnc machining center.

 

We are inspecting cavities with steep side wall forms. They are coming out OOT.

 

I believe the parts are better than the cmm is stating.

 

Since the walls are so steep (73 deg), a shift in X or Y of .003 translates into .010 shift in Z.

 

I thought if I can compensate or (pushout) my X & Y values by a .002/.003....this would bring my Z value back into correct position.

 

Any thoughts?

[mayday]

Whens the last time a tip qual was done? is this a DCC CMM? makes a big diferance. after doing a tip qual. go back and check your Tooling ball as a sphere and make sure the CMM is checking it the right dia. thats a begining, cause there is a lot more going on in that CMM than you want to know bout. as far as comps go, you mean comps at the machine or the CMM? in the machine just leave .002 stock on your finish pass

[kkominiarek]

comp in the cmm program

[mayday]

all prob comps are done internaly. the software does the comps based on vector direction when the hits are taken. typicaly comp is either on or off in the CMM, rarly off. this dosent mean the CMM is always right tho. bad tip quals will throw off every thing. have him/her check a gage ring or toolball / somthing calibrated to verify the CMM is right.

[chris m]

Ken

 

We just ran into this exact problem ourselves here and found that our CMM was unable to measure certain shapes accurately because it was not correctly compensating for the probe. We purchased a software upgrade to allow us to measure these shapes. You should contact the CMM manufacturer and see what they have to say.

 

C

[kkominiarek]

we did qualify the probe (many times)....changed probes also....Next step will be to check w/vendor to understand what are software can/cannot do....

[mayday]

What kind is it?

maybe I can give you some insight on things to check

[kkominiarek]

We uncovered the culprit.....the part has a curved shape on the bottom...when we go to inspect we set part in fixture and level it by eye.....we then use auto-plane to set the planes... we believe the auto-plane is not compensating the ijk values.......

 

we indicated the top surface.....ran the inspection program.....all points checked good