extension spring ends

[cjccmc]

I have an application where I would like to use an MS spring which calls for machine loops with a max opening (gap) of .014 inches. Because of space considerations I'm thinking of simply providing a hole in a tab and end loops thru these. Any reason to be concerned about stretching open that small gap to fit over a .08 thick tab? Spring OD is .240, wire dia .026, hole in tab maybe .07 dia.

 

[Cockroach]

No, not a concern other than noting you would be subtracting from total overall length, i.e. active coils.

You can also "thread" an end nubbin into the ends of the spring, the coils would lay between threads and therefore provide for an anchor point. I've done this several times using extension springs, it works quite well.

But for simplicity, bending the last coil orthogonal to the axis of the spring works as an anchor. That way you don't need to introduce additional parts to the sub assembly.

Good luck with it.

Regards,
Cockroach

 

[jagad5]

Make sure you check stresses in the extension spring hook. And depending on the manufacturing process, look for defects at the point where the hook transitions to the spring. Springs made automatically can have a little notch at that location, which is the point of highest stress in the entire extension spring. Failures can be the result.

Doug