Scanning cast conical ID, Evaluation and Filtering.

[[Tr...]]

So for our part, we have a conical casted surface that is an ID. I have to go down at specified depths along the cone and capture the diameter at the specified depths. Nominal diameter is 2.20 mm. I am scanning 390°, 390 points utilizing a 1.5 mm SiNi probe, Filtering 15 UPR, Low Pass.

LSQ provides pretty stable measurements, but does not reflect the true size, the result was larger than what the actual diameter is. (I utilized gage pins to verify this.)

So then I utilized Max inscribed and it was reporting smaller than what the actual diameter was. 

I utilized Minimum Feature and it was the closest result to the actual size of the conical diameter at that specified depth. 

 

I am looking for any and all help on this. I know that Max inscribed is primarily for machined parts and LSQ is primarily for casted parts. 

Just trying to figure out what is going to report as close as possible to the actual size.

[[Ma...]]

I don't think there is any "must use" rule depending on material/surface/and others.

If you are using pins, then tangential should behave the same as pins ( max inscribed, min circumscribed ) - but this method should be used with filters and outliers.