Freeform form profile calculation

[[Me...]]

Hello all,

I had an issue using Freeform, I wanna give 2 profile tolerances :
First one without datum and second one with datum D. My problem is when I ask for a profile form without datum, the error is bigger than the profile form with datum...
I wanna know I some of you have already had this kind of problem and if you know how Calypso would calculate this profile form.

Thanks for your help !
Guillaume

[[Ma...]]

Guillaume,

do you have a screnshot from your eavaluation? ❓

[[Cl...]]

The first part of the callout wants the form only. The second part wants form and position relative to Datum -D-

Just create two profile characteristics. One w/datum, one w/out.

http://dimcax.com/gdt_web/may-03.htm

[[Da...]]

Do you have any outliers that could be contributing to the results? Are the two results being evaluated in the same way?
I had a part the other day that two outliers where casing the calculator to shift the part one direction. When I removed those outliers the result dropped from 5mm profile to 2.5mm.
Not sure it this is your problem.

Thanks
Dan

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[[Me...]]

Hello all,
First thanks for your replies 🙂

Here is a screenshot showing the problem (I made a mistake on the second tolerance :p):

I have 2 profile characteristics, one with datum and one without. The problem is the char. with datum result is better than without.
I use the same element in the two characteristics (with the same evaluation method). There doesn't seem to be outliers.

The problem isn't the form default result because we where knowing it. It's only that the char. with datum is better than without, there is not so big difference (maybe 0.01) but for the principle.
I created severals form surface (and even curves) and I now have a better result (the char. with datum is worse than without), but no explanation why.

I'll try to find it out and would post here if I found 🙂
No one has ever had this king of problem ?


Have a good day

Guillaume

Capture.JPG

[[Is...]]

Normally is common to apply best fit when there is no datum in profile specifications.
so I think is necessary to set the alignment of the best fit in the Characteristic without Datum.

[[Me...]]

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I read on a freeform manual that if you select "no referencial" Calypso would do a best fit and give only the shape form.
I've tried to make a bestfit on my form and then set it in the characteristic and it gave me the same result (less than 0.001 mm of difference).
So I think both methods works 🙂

Guillaume