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# how to solve substract problem

Pioneer

version 12.0

I want to use the cylinder and the spiral to do the Boolean subtract operation. The helix body is achieved by a curve around the helix. The cylinder is shown in Figure 1. The cross-section of the sweep operation is shown in Figure 2. The Helix line is a helix. After the helix body and the cylinder are obtained, Using the Boolean subtract operation, as shown in Figure 6, the result is shown in Figure 7. It can be seen that the result is obviously wrong, the cylinder is spilled, not the desired result. What should I do? please help me, thank you very much!

29 REPLIES 29

# Re: how to solve substract problem

Solution Partner Legend

Hi, can you share the model?

# Re: how to solve substract problem

Siemens Phenom
1) Toggle on "Preserve shape" in the swept feature
2) Use Vector as alignment option in the swept feature, use the centerline of the cylinder as the vector.
3) Try use "Trim body" instead of Subtract, try trimming the cylinder using the thread faces,

This geometry you have created , is not very logical to the solid modeler, if you look at the thread, the same side faces are both interior faces as well as exterior faces. This condition is very difficult for the solid modeler to handle.
The fundamental logic there is that one side of a face is outwards and the opposite side is inwards. In this model they are both at the same time.

4) re-design the thread profile such that the in-out logic works.
Then the subtract feature will work too.

Regards,
Tomas

# Re: how to solve substract problem

Gears Esteemed Contributor

A couple notes:

- helix curves "twist" as you proceed along their length.  This is why you need to keep alignment (or whatever) to remove the twist

- You swept helical solid intersects itself (I think this is what @1u7obd  is trying to say).  Try to redesign the cross section so as you sweep it along the helix it doesn't touch itself.

Ken Akerboom Sr CAx Systems Engr, Moog, Inc.
Production: NX10.0.3.5 MP16/TC11.2
I'd rather be e-steamed than e-diseaseled

Pioneer

# Re: how to solve substract problem

Pioneer
I can not upload the NX.prt FORMAT FILE, I do not know why?

# Re: how to solve substract problem

Pioneer
thank you for care this question, but the actual situation is the swept model, this situation is the cylinder turning process, I want to simulation the process of material was removed, and then view the details of the machined surface

# Re: how to solve substract problem

Pioneer

thank you, the first notes, I do not know how to remove the twist, and the second is the actual situation is that, this model simulates the process of cylinder turning, so please give me a suggestion.

Siemens Phenom

Regards,

# Re: how to solve substract problem

Phenom

Hi @N12X

Following what other people said as you see in this image your swept feature has a self intersection. Each turn of your swept body has interference with the next turn.

Here are some of the ways to remove this self intersection:

1- make the section triangle used in the swept feature as small as possible. You only need the portion that intersects with the cylinder. try to trim the portion coming out of the cylinder.

2- increase the pitch value of your helix (if possible)

Regards