Helix with Radius by Law Curve in NX8.5

[PSI-CAD]

Hi,

Open the part
Edit the Helix
Change the limits to a value different of 100
or
Change the methods to Turns and change the turns to a value different of 33.33

The helix doesn't follow the sketch I would like to know if ths behaviour is right or if it's a limitation

Thanks in Advance


Regards
Didier Psaltopoulos

http://www.psi-cad.com

 

[cowski]

It is working correctly. When you change the limits or turns, the helix length is now longer than the "law curve" reference. The shape of the law curve now 'maps' onto the new length since there is not a 1:1 correspondence. You will notice that after the change the proportions of the helix are the same as the driving law curves. If you want the helix to exactly match the sketch, change the helix limit from a "value" type with a value of 100 to a "formula" type with a value of "Height" (the same expression value that drives the sketch). Now you can use the sketch to change the shape/size of the helix and use the helix command to change the pitch, handedness, etc.

www.nxjournaling.com

 

[PSI-CAD]

Hi Cowski,

I agree with you if I increase the number of turns more than 33.33. But I can imagine that it could be possible to have an hélix with 30 turns and have the radius following the sketch


Regards
Didier Psaltopoulos

http://www.psi-cad.com

 

[cowski]

In that case, your helix will be shorter than the law curve; the helix will map to the curve so the proportions are the same. If the radius followed the sketch, but the helix length is shorter than the sketch, you won't get the same proportions as the law curve. When you use another curve reference to drive a law curve, you can think of it as a shape template.

www.nxjournaling.com

 

[JohnRBaker]

The sketch is being used to control ONLY the Radius of the Helix and nothing else. If you wish the height to ALSO be controlled by the sketch then you will need to do something like the attached example (I linked the 'End Limit' to the Height expression of the Sketch).

John R. Baker, P.E.
Product 'Evangelist'
Product Engineering Software
Siemens PLM Software Inc.
Industry Sector
Cypress, CA
Siemens PLM:
UG/NX Museum:

To an Engineer, the glass is twice as big as it needs to be.

 

[PSI-CAD]

Thanks Cowski for your answer,

Hi John,

I know this, but I don't want the height to ALSO be controlled by the sketch. I looked a way to create an hélix with 30 turns following exactly the shape of the sketch until 90mm for example (30*pitch).

What about an Enhancement Request ?


Regards
Didier Psaltopoulos

http://www.psi-cad.com

 

[JohnRBaker]

So in reality, what you're saying is that you want the helix to follow the shape of the sketch exactly as the number of coils increase or decrease. In this case the constant radius section will stay the same while any change will probably occur in the tapered section, correct? If so, I'll think about this a while and get back to you if I can think of a way to do it.

John R. Baker, P.E.
Product 'Evangelist'
Product Engineering Software
Siemens PLM Software Inc.
Industry Sector
Cypress, CA
Siemens PLM:
UG/NX Museum:

To an Engineer, the glass is twice as big as it needs to be.

 

[PSI-CAD]

Hi John,

Yes that's right. Thanks in advance to have a look


Regards
Didier Psaltopoulos

http://www.psi-cad.com

 

[JohnRBaker]

OK, look at the attached model. The only difference is that since I'm controlling BOTH the Sketch and the Helix at the same time, I had to create explicit expressions for the number of coils, the pitch (this is optional if it never changes) and the limits of the Helix. So when you want to change the size of the Helix edit the expressions and NOT the Helix feature itself.

John R. Baker, P.E.
Product 'Evangelist'
Product Engineering Software
Siemens PLM Software Inc.
Industry Sector
Cypress, CA
Siemens PLM:
UG/NX Museum:

To an Engineer, the glass is twice as big as it needs to be.

 

[PSI-CAD]

Thanks a lot John, this could be a good solution so simple !!


Regards
Didier Psaltopoulos

http://www.psi-cad.com