topic Re: This surface offsets but won't thicken? in Fusion Design, Validate & Document Forum

This surface offsets but won't thicken?

Anonymous — Wed, 30 Oct 2019 16:23:01 GMT

Hello,

As above - I occasionally get surfaces that fail to thicken, despite being able to create offsets of them, which i had imagined to be a similar calculation.... Currently my only solution is to import them into rhino, where for some reason the surface thicken tool seems to be more forgiving.

Anyone else having this issue, any ideas?

Note - I made this example in a hurry so apologies for the slightly messy timeline!

Re: This surface offsets but won't thicken?

jeff_strater — Wed, 30 Oct 2019 17:03:25 GMT

@Anonymous - I was able to thicken this to 20mm. Is there a particular value/direction for which Offset works, but Thicken does not? (BTW, you are correct - Offset and Thicken use similar APIs in the kernel)

Re: This surface offsets but won't thicken?

Anonymous — Thu, 31 Oct 2019 08:18:33 GMT

That's interesting. I was trying to thicken to 4mm. I also tried several other similar figures. 20mm works on my end, as it seems does anything down do around 8.

It looks like anything below approx 8mm can be offset but not thickened. Offset will also work in either direction, whereas thicken will not (doesn't work symmetrically either).

Finally - The thickened component does not have an entirely uniform thickness. I get a 'bulge' close to the bottom edge like in the below image..?

Re: This surface offsets but won't thicken?

laughingcreek — Thu, 31 Oct 2019 15:58:01 GMT

lofts like to be 4 sided. when ever you do a 3 sided loft it bunches at the tip, and is frequently difficult do perform other things on. I think for something like this you need to create an overbuilt surface and trim it. see attached. this will thicken.

Re: This surface offsets but won't thicken?

Anonymous — Thu, 31 Oct 2019 16:07:08 GMT

Interesting! So the issue is that the two loft profiles in my version coincide with each other on one end?

That's very helpful, thank you.

Re: This surface offsets but won't thicken?

laughingcreek — Thu, 31 Oct 2019 16:41:13 GMT

that is what I believe is causing the problem here.

this-

Vs. This-

Re: This surface offsets but won't thicken?

jeff_strater — Thu, 31 Oct 2019 20:51:21 GMT

Interesting, @Anonymous - I had not noticed the non-uniform wall thickness at 20mm. That needs to be looked at as well. Got some homework to do... Until then, listen to @laughingcreek 's advice (which is always a good idea anyway)

Re: This surface offsets but won't thicken?

jeff_strater — Sat, 02 Nov 2019 00:14:14 GMT

I did run this by the modeling kernel team. @laughingcreek 's explanation is spot on for why the surface has problems. However, it still seems wrong to me that:

20 mm thicken is so non-uniform
4 mm thicken fails, but 4 mm offset succeeds

We are looking at these issues, thanks for sharing the model, it helps us to get these hard-to-model cases.