Trying to do a boolean cut

[oldgeek]

Hello.

My first time here. I hope I'm posting in the right place and am doing everything correct. Correct me if needed please.

So, I'm trying to make a boolean cut for some threads I made on this part. I'm including the file attached. I tried to select the "Revolution" and then the "Sweep" in the Part interface, then click on "Make a cut of two shapes". When I do, it just sits there not responding. I have even left it for a hour or so.

Here are the Freecad particulars:

OS: Windows 10
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.16.6706 (Git)
Build type: Release
Branch: releases/FreeCAD-0-16
Hash: f86a4e411ff7848dea98d7242f43b7774bee8fa0
Python version: 2.7.8
Qt version: 4.8.7
Coin version: 4.0.0a
OCC version: 6.8.0.oce-0.17

I am running a core i5 with 10gb ram. BUT with just the onboard graphics. Is doing this cut too much for my system? Or what am I doing wrong or how should I go about doing this?

Any help is appreciated. I do like this program.
Thank you
Greg

[chrisb]

If you select the sweep and make in Part Workbench a Menu->Part->CheckGeometry you see that your sweep has self intersections. The check takes some time, and I have none of it to investigate the problem further. Hope it helps.

[triplus]

Hi @oldgeek.

I tested the Cut on FreeCAD development release and OCC development release close to version 7.1.0. Boolean cut operation is completed under one minute and the result is not a valid solid. I didn't test this but in general you don't want to make Sweep diameter the same as Revolution feature diameter. As coplanar faces like that can cause a lot of issues in boolean operations. Make the thread slightly "stick out" before making the boolean cut and try again. What i decided i will test is multiCut method with Fuzzy Boolean tolerance value set. Without changing anything else and after around the third try to get the tolerance right:

Fuzzy_0.0001.png (118.53 KiB) Viewed 1337 times

It worked! Part -> Check Geometry doesn't show any errors on the produced shape.

[oldgeek]

I extended the thread and now it will do the cut. But like the picture posted by @triplus, it cuts out the profile of the thread, which is opposite of what I'm wanting. I am needing the thread sweep to remain.

[triplus]

I extended the thread and now it will do the cut.

Great.

But like the picture posted by @triplus, it cuts out the profile of the thread, which is opposite of what I'm wanting. I am needing the thread sweep to remain.

Can you explain this a bit better as i don't understand what you are after. You would like to reuse the original Sweep feature? Or do something else?

[sgrogan]

I extended the thread and now it will do the cut. But like the picture posted by @triplus, it cuts out the profile of the thread, which is opposite of what I'm wanting. I am needing the thread sweep to remain.

Ahh, this make more sense.

Can you explain this a bit better as i don't understand what you are after. You would like to reuse the original Sweep feature? Or do something else?

The thread should be shifted out and added as a fuse, or flipped and cut. The sketch will need to be re-worked.
@triplus look at your screenshot, the thread is undercut. I thought this was rather fancy.

t.PNG (24.45 KiB) Viewed 1306 times

@oldgeek is still going to have a problem as chrisb has pointed out. Check geometry w/ BOP checks true fails with self-intersects on occ 6.8 and passes on occ7.0

[triplus]

The thread should be shifted out and added as a fuse, or flipped and cut. The sketch will need to be re-worked.
@triplus look at your screenshot, the thread is undercut.

Well @oldgeek if this is what you are after indeed you will need to change the geometry of the sketch first.

I thought this was rather fancy.

I guess rather fuzzy.

[Willem]

Hi, I see a problem in the sketch for the revolution. Strange enough the revolution succeeds in spite of the redundant line, but it gives problems while making the cut

Schermafdruk van 2016-12-01 23-29-46.png (233.21 KiB) Viewed 1289 times

[sgrogan]

Hi, I see a problem in the sketch for the revolution. Strange enough the revolution succeeds in spite of the redundant line, but it gives problems while making the cut

Nice catch. I just tried to change the diameter in the revolution to avoid the co-planer faces and the revolution developed an error. This explains it.
@ oldgeek what thread are you trying to achieve.

[oldgeek]

Yes, I thought I had finished that chamfer in the bottom of the hole. The lines need to be trimmed at the chamfer there. I did that, and extended the thread out a bit, but now am getting the results as @triplus.

The thread I am trying to do is a stub acme thread. The profile of the sweep and the geometry it is based on is the profile of the thread itself. So, it is what I am wanting to remain instead of having it cut out.