Catia Helix - Revolutions 1

[DAE62]

How am I able to assign the revolutions within the Helix curve definition? It is not highlighted within the dialogue box. I need 8 revolutions for a 6.00 in. long helix.

Thanks.

 

[Kapitan]

Ignore the units, I'm working in millimetres, here's a helix with a pitch of 7.5 and a length of 60 (giving 8 turns).

A radius wasn't mentioned - and it doesn't really matter. Every parameter of this curve can be modified afterwards.

Editing the coordinates of the Start Point (I used R100) will alter the radius, the misleading term is "Height" - that really means axial length (of the helix). The length of line used for the "Axis" is irrelevant - it just provides vector direction.

The number of turns is the Heigth / Pitch - it doesn't explicitly ask for them...

​

 

[DAE62]

I was able to do this, but what if I have the revolutions, height and diameter? I can't figure out how to assign the number of revolutions.

Thanks for your time.

 

[Kapitan]

Suppose we are to construct the following helix:-

[ul]
[li]Revolutions = 8[/li]
[li]Height = 60[/li]
[li]Diameter = 200[/li]
[/ul]

V5 asks for Start Point, Pitch and Height, it could have asked for Radius, Revolutions and Height, or Radius, Revs and Pitch; but they chose the first option.

If the (number of) Revolutions was asked for in addition to the current parameters then we'd have a case of double definition. Forgetting the radius for a minute, only any Two things are required - the third is a function of those two.
[ul]
[li]Revolutions = Height / Pitch[/li]
[li]Height = Pitch * Revs[/li]
[li]Pitch = Height / Revs[/li]
[/ul]

The values for Height and Revs can be used directly in the Pitch box, as shown below.
The start point has been renamed in the Tree for clarity.

​

 

[Kapitan]

I forgot to add that the Revolutions option becomes active when a Pitch Law is used. Variable pitch helices are obviously quite a different case to the Constant Pitch Helix in question earlier.

Here's a Variable Pitch 'S' Law case with the pitch after one turn being 10mm, and at the last turn equal to 100mm.

The Pitch box has now been nulled, the Revolutions box is active.

​

This is the Law being set up...

​

If you wanted a specific Law - such as a helix whose pitch accelerates in a parabolic manner, and didn't slow down then you could draw the law - somewhere in the model.

 

[DAE62]

Thanks!