Having trouble when modelling screw threads

I need help. I tried to follow a tutorial on modeling screw threads on this software, but when it came to the fillet portion, it does not show the same result as in the tutorial. Any advice is deeply appreciated.

details of the problem:
in the video tutorial, it was stated that one of the steps was to fillet the edges of the solid that was around the cylinder. It would produce nicely rounded edges. But when I tried to do the same, it ended up producing a messy cluster of surfaces.

Hello- please post your file.


We would need the actual file, obviously something has gone wrong but we can’t say what.

Of course the first rule of modeling screw threads is to NOT DO SO unless you really have to, or maybe download hardware with them from an online library. There are very few applications where brute-force modeled threads are actually used.

I am not able to give you the original file as it is confidential (viewable only from my company) but I could give you this
Fillet problem.3dm (533.1 KB)

There are a couple things important:

The fillet you are going to apply needs to be small enough so it doesn’t overlap itself. I found the max. fillet is about 0.007 inch
Since this is such a tiny fillet, it means your document tolerance (0.01) is way too coarse to make this happen.

Due to this tolerance, I suspect this trim has gone wrong, see the wavy/double trim lines:

If I tighten your modeling absolute tolerance to 0.0001, explode the shape and extend the screwthread surface, build a new cylinder, then make a new unioned shape, FilletEdge will work fine:

Fillet problem solved.3dm (3.1 MB)


Looks like another reason to implement dual tolerance for Trim, Split and Protect, as I suggested a while ago in another thread.

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Thank you very much :smile: