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The easiest way to make a spring to make it flexible is as follows : (because the helical sweep doesnt change the pitch when you change the spring length, with this method it acts like a spring)
Create a variable section sweep of a surface. The sketched line defines the height and is also changed with 'make flexible' in the assembly (see picture 1)
In the sketch of the sweep add a relation controlling the angle (see picture 2). p is the pitch here driven by a parameter.
The easiest way to make a spring to make it flexible is as follows : (because the helical sweep doesnt change the pitch when you change the spring length, with this method it acts like a spring)
That's a whole lotta construction for an "easiest" way !
I have no need for all this when working on this base :
<UL>
<LI>make sure you have 2 parallel datum planes and a orthogonal plane to sketch the central axis of the spring</LI>
<LI>start the helical sweep on the bottom plane, defining the pitch at anything you like at that moment and construct the feature</LI>
<LI>define a parameter for "number of curls"</LI>
<LI>define a relation setting "pitch" equal to "distance between datums" divided by "number of curls"</LI>[/list]
Et voila, by magic you have a spring adapting to the distance between 2 datums. The spring can be attached to at both ends since it sits between datums.
I have a two layer family table for die (compression) springs because we use lots of them.
The first layer has the our selections of the manufacturers range of die springs with all their characteristics including free length and free pitch. The second layer has a single parameter, the compression in mm increments from about 4mm to 20% of the free length which is sufficient for my purposes.
The modelled pitch (including closing of the ends) is a function of the free pitch and percentage compression.
As shown in the picture, the compression dimension has values for maximum compression, pre-load converted to kg and current length embedded into it which are revealed by picking the "TOP PLANE". All this information is highly relevant to me because I need to counteract known masses.
It is probably more work (table currently has 215 instances and growing) but you only need to create them once then you have them forever.
the springs aren't used in an ordinary assembly. They are typically used in several 20 component generic assemblies that each have many instances each calling for different combinations of springs and extensions and many other degrees of freedom. Several higher level sub-assemblies then each call up combinations of these assembly instances and a typical higher level assembly still calls several of these sub-assemblies so the top level assembly ends up with potentially several different extensions of the "same" spring as well as other springs with different free lengths and spring rates all buried 2 layers down in the assembly.
Also, each of the sub-assemblies contains 2 pairs of two springs
(usually the same but not always). When I need to change springs I only
need to make the alterations by editting the assembly family table and
verifying which is much faster than editting the 100 component
sub-assemblies or the 1000+ component top-level assembly.
From what I have seen of flexible components they are more of a quick and dirty way to achieve what can be done with instances but they come at the cost of less overall capability, much like the hole function that can't do everything that revolved cut/cosmetic thread can, and I couldn't see my way to getting what I needed out of them in this case.
Cheers for the update, now i can understand why you do it that way. I've used to do it with std profiles (I, U, T etc) for the lenghts to get the bom tables in order. Guess I've been away from mechanical engineering for too long
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