Measuring Chamfers

I am using powerInspect for my infinite romer arm.

I am having a hard time figuring out the best way to measure a chamfer.

My exampler today was measuring the chamfer on a hole for a bolt on a wheel/tire assembly.

I was ablt to get some sort of .20 x 60 degrees measurements using calipers and a protractor, but i am hoping there is a way using PowerInspect.

I am new to this field and any help would be greatly appriciated.

Brian

Measuring chamfers that small will be a problem for ANY CMM-type device. The points will have to be too close together and with close-points the accuracy of the device comes into play, BIG TIME! If your machine is only accurate to a couple thou (0.002"), then you have to measure a cone with your points ONLY 0.18 apart (max, ya gotta stay away from the edges!), the possible build-up of equipment error can easily climb to MORE than the tolerance given. We had a job in here that they wanted a chamfer measured. I took the calibrated data from the CMM (yes, a CMM, not an arm) and figured out HOW much the angle of this little chamfer could change just from the repeatability from the certification (less than 0.0004") and the angle could change by as much as 9 degrees (in this case). A tolerance of +/-0.5 degrees for the chamfer but an uncertainty of 9 degrees from the equipment? Nope, couldn't do it. Of course, this chamfer was smaller than yours, but your Romer isn't any where near as 'good' as a CMM (in reality, you can not expect better than 0.002" on that arm, more like 0.005") so at best, you will have 5 times the uncertainty that I had for my chamfer.

i tried setting up a cone i tried it with 2 different probes. i measured it by hand at about 60 degrees and power inspect told me it was around 42...am i just not thinking about the angle correctly or is the range of accurancy much much higher as previously stated.

brian

i tried setting up a cone i tried it with 2 different probes. i measured it by hand at about 60 degrees and power inspect told me it was around 42...am i just not thinking about the angle correctly or is the range of accurancy much much higher as previously stated.

brian

I think the issue is entirely in your equipment. They 'claim' those arms are good to within tenths, but most people that use them (that I have spoken to and read on these sites) will tell you that a tape measure can be as accurate. Don't expect anything better than 0.005" accuracy out of an arm (so I have heard) and at that big of error, you could easily see 20-30 degrees difference from the actual of a cone that size.

well thats just great....