3D Offset Tool Difficulties...

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R23D
Posts: 135
Joined: Sat Jan 25, 2020 5:23 am

Re: 3D Offset Tool Difficulties...

Post by R23D »

Well, I'm not fully sure how to accomplish that but I may have to. I just removed a few of the fillets which I didn't need for this purpose in the negative and it still failed so, as an experiment, I then removed ALL the fillets and it STILL failed.

I can only get this tool to work on the simplest of shapes and I'm not sure why you would ever want to use this tool on a primitive like a cube... you really can just make the cube bigger and in that instance it WILL be the same thing...

Stripped down, my model now consists of nothing but a few Boolean unionid and differenced primitives with the addition of 1 extruded shape.

I've got to say, I don't think this tool really works. :(
heda
Veteran
Posts: 1348
Joined: Sat Dec 12, 2015 5:49 pm

Re: 3D Offset Tool Difficulties...

Post by heda »

there are plenty of posts or wiki material on how to design with spreadsheets.
you will make it easier on yourself if you use sketches for the base profile and side profile.

take the hole that you have in your pedestals, what do you think the computer should do when the offset is large enough to close the hole, or should it switch normal and offset the hole in negative direction, and everything else in positive?

a hole that gets closed during a 3d offset is one example of degenerated topology.
edit: coplanar surfs is another example of things that can lead to degenerated topology.

offsetting an arbitrary pierced body is not trivial, and there are situations that simply do not work, not because it is fc, but because it is not mathematically possible...

here are some features of your model offset, so the command works, but as you have found out - not on everything...
Attachments
some_offsets.FCStd
(51.23 KiB) Downloaded 15 times
Last edited by heda on Sat May 28, 2022 6:01 am, edited 2 times in total.
R23D
Posts: 135
Joined: Sat Jan 25, 2020 5:23 am

Re: 3D Offset Tool Difficulties...

Post by R23D »

Ok. I've kind of got it to work. Well, well enough for my purposes in this instance. I have discovered if I remove all fillets except the ones on the pivot support blocks which I need for this purpose and I correct the fact that the 2 cylinders used to subtract the pivot holes were accidentally coplanar with one side of the model (I know not to do this - don't know how that happened). IT WORKS! ...only on certain settings, mind you ie. 'arc'. But I'm not complaining. It's good enough for what I want to do right at the second.

So, releived!
R23D
Posts: 135
Joined: Sat Jan 25, 2020 5:23 am

Re: 3D Offset Tool Difficulties...

Post by R23D »

Oh... Sorry... didn't see you had posted something just before me. I will check that out, tomorrow. Thankyou for helping me.
heda
Veteran
Posts: 1348
Joined: Sat Dec 12, 2015 5:49 pm

Re: 3D Offset Tool Difficulties...

Post by heda »

right, at least you found one of the culprits, looks like that is the one as well

btw, you never mentioned how much you intend to offset

if someone wants to take a stab at improving 3d-offset, this could be one test model to use
one thing that could be done is a live indication that it is nok, now the live indication (update view) shows nothing when nok, maybe have some symbol ok/nok in taskpanel making it fully clear when it works or not
R23D
Posts: 135
Joined: Sat Jan 25, 2020 5:23 am

Re: 3D Offset Tool Difficulties...

Post by R23D »

Just by 0.2 mm. Nothing that would cause the holes to close or any self-intersection.
R23D
Posts: 135
Joined: Sat Jan 25, 2020 5:23 am

Re: 3D Offset Tool Difficulties...

Post by R23D »

here are some features of your model offset, so the command works, but as you have found out - not on everything...
In your example file, it is interesting to note that you have chosen 'intersection' for the join setting, which is what I am ideally trying to get to work but freecad is using 'arc' regardless of what you have set. When I choose 'intersection', I don't get 'arc', I get failure.
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