Variable pitch spring

[mgnt8]

OK mr. & mz. helpers out there, I need some help with springs.The best way to model a variable pitch spring? The spring has 24 coils, wire diameter of .027", & 3/8" O.D. but some coils are sitting right next to each other, some aren't. 3 coils touching at the bottom, 3 coils at the center & 3 coils at the end are all together. The other look like .200" pitch.
Edited by: mgnt8

 

[dr_gallup]

Springs are best modeled with a helical sweep. Just add points everyplace along the sweep profile you want to specify the pitch. In your case you are going to need to specify the pitch at 10 points along the sweep profile. You need 5 regions of constant pitch (.027 & .200) and 4 transition regions between them. So in your case, you need a starting pitch of .027 @ 0 and .081 (3 closed coils), then a short transition length (this can be very short) to get to your .200 pitch @ say .090. Keep going like this for the whole spring.

View attachment 1688
Edited by: dr_gallup

 

[mgnt8]

Thanks dr_gallup. That is exactly the information I was looking for.