Springs and moving parts!

Okay, so I've got the sear, that sits on (and rotates around) a pin. I've got a tangent constraint on this, and it appears to work. Now, at the bottom of the sear, I've got another pin sticking out of it, and I've got a spring that has to work on that pin. It's a torsion spring, and the coil has to ride on the pin. The bar that comes out of the back side of the spring acts on another piece (not present yet, for simplicity's sake) and the hook has another spring - an extension one this time - that connects it to the trigger.

My problem is the spring. I can manually position it to fit on the pin, but I can't seem to get the same result with constraints. An insert constraint doesn't recognize the coil as a valid concentric reference, and tangent constraints don't seem to work either, because the pitch of the coil throws it off. I tried a mate of the end of the coil against the side of the sear to hold it straight and keep the tangent from throwing it off kilter, but again, that tries to lay as much of the side of the coil as possible against the sear, and just makes the angle problem even worse.

Any suggestions?

(Oh, and for the moving parts side of this: the sear and sear pin are assembled with a tangent constraint at the moment. When I finish assembling this and start doing animations, will that be sufficient to keep the sear on the pin, rotation wise? There will be constraints placed on it with regard to the side plates of the trigger housing as well, to keep it from coming off the ends of the pin, but I know how those will work so I'm not worried about them at the moment.)

sear 1.zip

sear 2.zip

Delete that tangent constraint - it is no correct constraint to use. (you can test this by simply clicking and draging the Sear - it does not stay on the pin)

Method 1 Constrain the Pin with an Insert constraint and enter offset distance to center on the pin.

Method 2 Constrain Mate the outside cylindrical face of the pin to the inside cylindrical face of the hole (this will pick the axis of the cylinders to mate). You would then need a Mate (probably Flush) between workplane in pin and workplane (or face) in Sear.

For the Spring turn on the visibility of the Y Axis (under Origin folder in the browser. Use the Mate constraint selecting the axis and the pin cylindrical face.

I noticed that your sketches are not constrained. Poor practice. In fact, your Pin circle sketch is placed at the origin but not constrained to the origin - this should be automatic. You might want to read this document http://home.pct.edu/~jmather/AU2006/MA13-3%20Mather.pdf

And you should mention when you are not using the latest release as you are likely to get solutions you can't open.

thanks ... looks like it worked out well! I'll probably be back with more questions about the springs themselves ... I really appreciate the help!

These are older parts, which is why the sketches are not constrained. the new ones have all the constraints set correctly. I haven't gone back and redone the sketches for the older ones yet.