Can anyone tell me what exactly this command does? Using 2020 R2
Other than putting SIMTOLX after my FCF I don't see anything different then if I didn't use it.
Many geometric tolerances are meant to be considered simultaneously. For example, when position and/or profile tolerances reference the same partially constrained datum reference frame, you should usually consider them simultaneously.
If you have a hole that is Ø6±0.1 with a TP of 0.1(M)|A|B(M)|C and another hole that is Ø4±0.1 with a TP of 0.2(M)|A|B(M)|C, it will evaluate both the holes together as they shift about Datum B.
If you go to Help in PC-DMIS and search for Simultaneous Tolerance, it will explain exactly what it is used for!
A simultaneous requirement applies to position and profile tolerances that use the same datum reference frame (same datum references in the same order of precedence and at the same material conditions). This forces the tolerances to be considered as a pattern in that there is no translation or rotation allowed between the coordinate systems established by each tolerance.
In other words, any unconstrained (or partially constrained) degrees of freedom can be optimized, but the optimization cannot be different for different tolerances featuring a common DRF. This will put a tighter restriction on the allowed optimization, typically making results look worse than without evaluating simultaneously. It is a requirement of Y14.5 to evaluate common DRF's simultaneously.
Consider a primary datum plane A with normal vector along Z+ and a secondary datum cylinder B with axis along Z. This DRF is unconstrained in rotation about Z. Imagine two separate patterns of holes with each hole having an axis along Z. Assign a position tolerance to each pattern using DRF [A|B]. You can take advantage of the unconstrained rotation to optimize the results for each pattern, but you can't optimize by a different amount for each pattern as it would not be representative of part function. This, in effect, ties the two patterns together although not explicitly.
My issue is that I don't see any change in the True Position calculations with or without using the SIMTOL, am I missing something?
Can you give us some more information about what you are measuring? What types of feature? What are the datums? What is the print callout?
Without specifics, all I can offer is that If the DRF is fully constrained, there is no wiggle room for SIMTOL to shift anything. Maybe that is what is going on.
I wrote a dummy program using the surface of my Rayco plate as +Z and 2 posts as
and [C]. the first set of dimensions are using the SIMTOL, the second set are the same features without the SIMTOL but with the same result
Not extremely versed with GEOTOL. However, in Xact, insure D2 and D3 axis are checked within each of the DRF's (seems to only be checked for "DIAMOND_08")
Also, in Xact, if you update a DRF within a SIMTOL group, the group will NOT update - you'll need to reconstruct the SIMTOL entirely to have the change(s) be applied.
I wrote a dummy program using the surface of my Rayco plate as +Z and 2 posts as and [C]. the first set of dimensions are using the SIMTOL, the second set are the same features without the SIMTOL but with the same result
Somebody more knowledgeable would have to confirm this (perhaps
neil.challinor ), but I believe if your considered features are OOT even after optimization, the result will be reported without any optimization.
To test this, report the same three dimensions with the material modifiers removed (simultaneous tolerance need not explicitly apply) and check to see that the values are the same.
Does simultaneous requirement apply when there is no datum modifier and no tertiary datum? I have a bolt pattern to A|B and a profile of the outside to datum A|B, A is the bottom face and B is the ID. Because my bolt circle is rotated from the outside profile, can both call outs be checked using a best fit for each feature?
