Part Accuracy

[dross]

I'm not sure I understand part accuracy. I model thingstha have very small edges (.0001"), very small tolerances (+/-.00002) with an overall part size of .250 x 6 x 10". I often have patterns on these parts that consist of as many as 9000 extrusions, each with these small edges. Regeneration time is huge. I know that reduced accuracy results in shorter regen times. What I don't know is what the accuracy really needs to be to accomplish what I'm doing.


How does this accuracy affect the model? Would too large of a tolerance result in an inaccurate model?


Sign me,


Baffled.

 

[dr_gallup]

If you don't have sufficiently small accuracy value, Pro/E will complain about geometry errors. Pro/E will say a feature "creates a small edge or surface". If you don't have any geometry errors and your part regenerates successfully then you have no problem. Back off on the accuracy a little if you want to. When you get to the point that Pro/E can't regenerate the part you have gone too far.

 

[dgs]

With those kinds of details on comparatively large parts, you need to make sure you're using absolute accuracy instead of relative.

I don't think accuracy will affect how accurately your parts are built, rather it determines how small of a detail you are allowed to create. How that is determined depends on the type of accuracy you are using.

Relative accuracy (the default) is a ratio between the largest edge in the part and the smallest allowable edge. The larger the part, the larger the smallest allowable edge will be. So, if you need tiny edges on a large-ish part, relative won't do it. I've had nothing but trouble with relative accuracy and haven't used it for 10+ years.

Absolute accuracy is an explicit definition of the smallest allowable edge. So, absolute accuracy of 0.0001" will allow edges down to 0.0001", regardless of part size. Sounds like you should set your default accuracy in your start part to absolute at 0.0001" or so.

As far as regen times, well, with higher accuracy comes longer regen times. For you patterns, make sure you're using identical patterns where possible. It's under the 'options' tab during pattern definition. Identical pattern members cannot intersect each other and pretty much have to be, as you might expect, identical in what they intersect, etc. not always possible, but they regen much, much faster.

 

[dross]

My patterns start with a datum point that is patterened, then the extrusions are a reference pattern. Would this make a difference in regen times?

 

[dgs]

Sure, you've doubled the number of features it must create. I'm not sure that it'll take double the time, but the generation of thousands of datum points is not insignificant.