curved spring

[warmwinds]

Has anyone been successful at modeling a curved spring. Using helical sweep, I can sketch a curved trajectory but the axis of revolution is always straight and this produces a cone shaped spring. I want the spring diameter to be contant and I want the spring to gradually curve about 20 degreesaround an arc (i.e. like a partial toroid).


Thanks in advance.

 

[Dbudworth]

try using a var sec sweep with a trajpar relation, this creates a helical surface. Then you can use the surface as a "tangent curve" trajectoryfor a swept portusion. Take a look at the attached jpg.


DanView attachment 445

 

[whit2498]

how do you make a curved spring with variable pitch

 

[Dbudworth]

the pitch is in the relation. When in the sketcher mode, go to sketch, or tools and select relations. Type in the relation of sd?=trajpar * 360 * 12


where sd? = an angle dim in the section


the number 12 in the equation = the number of revolutions over the entire length of the trajectory.

 

[Israr]

whit2498,


Create a parameter for the pitch and relate it to the path of the curve, for example as the path increases the pitch increases and at the end the pitch decreases.


sd?=trajpar * 360 *p


where p is the parameter





Israr

 

[jbuckl]

Israr, to make 'p' variable according to trajpar it has to be referred to another variable control such as a graph. This is a hugely powerful method for controlling the end coils, however, there has to be a tangenttransition between pitch changes or the helical surface will fail or be usless to make the protrusion with. In order to make the tangent transition between pitches, include a fillet/round in the graph that controlls the pitch change.


If the above seems unnecessary to you, can you suggest what kind of relation expression would replace the graph control for pitch variability, bearing in mind the requirement for a transition?


In this context, I'd love to know if any other CAD system has this functionality, I cant imagine which.