Surface profile / flatness

[Peter DeGroot]

Hi,

I'm using 3.7 mr2 on a "One" machine PH10T / TP20 2mm x 20mm ball stylus.

I have 4.1 and have played with it, but I am not ready to use it for production purposes yet.

I'm using igs models translated from solidworks. I am working with .125 stamped / formed stainless. Nothing is straight, flat, or round in my world.

I have a few questions regarding surface profile of curved surfaces and the profile / flatness of flat planes.

Currently I use vector points to construct a flat plane. I am still not clear on the differences between auto - bestfit - bfrecomp .........I then dimension the constructed plane with the Profile utility. I was told that autoplane is not very stable so thats why I use vector points. Is this still the case in 4.1?

1. Am I better off dimensioning profile for each individual vector point? Or the constructed plane?
2. How does the "Snap Point" utility work and how does it affect A-the constructed plane / and B-the profile value of the individual point(s)
3. What is the flatness value of a constructed plane telling me? The max difference between highest (say in the Z axis in this case) and the lowest vector points? How does snap points change this dimensioned value? How does auto / bestfit / recomp / affect the flatness value?
4. What is T value telling me?
5. How does the approach vector get determined on curved surfaces in a igs cad? (using auto vector point)

I've been at this for about 2 years. Mostly self taught. Try to dumb it down a bit for me eh?

Thanks in advance. Go Badgers and go Packe......OK........ just Go Badgers!

Peter DeGroot

[\v/inston]

all the answers to all these questions can be found on this forum in old posts.

[Jan d.]

I am also a self taughterererer. Anyway, I also use vector points for my surfaces and then construct a plane. And I have worked with this extensively for the last half year.

Here is what I found:
1: profile works great on the constructed plane. No need to do individual points. However, I do run into some problems with profile to multiple planes at the same time. I am not sure whether PC-DMIS does do that right.
WARNING: the results from PC-DMIS are confusing. Only use Min/Max and you will be fine. See this link for more details.

http://www.pcdmisforum.com/showthread.php?t=2210&highlight=profile

2: No idea.
3: Flatness tells you what distance is between the highest and the lowest point. It does not give you any positional or orientation, which is exactly what profile is intended to do.
4: I found that the T value also gives decent correlation to profile. However, why not use the XactMeasure profile? It works like charm.
5: no idea.


Jan.