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Fabricating a spring beyond engine lathe capability

wepllc

Aluminum
Joined
Apr 19, 2010
Location
Kentucky
Hello,

I want a make spring that is beyond my lathe's capability to fabricate. The maximum number of turns I can make on my lathe is 4 turns/in (pitch = .25 in). If I want make a spring that has 3 turns/in (pitch = .333 in), can I make the spring by first winding it at 4 turns/in then plastically deforming (straining) it on the mandrel by stretching it out to 3 turns/in? Would I have to temper the spring wire to relieve any residual stresses?

Thanks,

P
 
For a spring of that size, maybe consider hot winding.

Tempering springs is a complex problem that depends on a lot of factors such as the type of spring and the material.
 
If the ID/OD isn't much larger than 1"/2", I suggest buying a pre-made die spring. Most of the standard industrial and tooling suppliers carry them. The catalogs give you dimensions, spring rate, and available travel, and all the uncertainty about manufacture and heat-treat are handled for you. These springs are typically available in four "strengths" for a given size, over about a 3:1 or 4:1 range of stiffnesses/strengths.

If you need a bigger OD, the actual makers will usually do customs. Lamina, for example (now part of Misumi, maybe?), offers custom springs up to 9.5" OD.
 
Hello,

I want a make spring that is beyond my lathe's capability to fabricate. The maximum number of turns I can make on my lathe is 4 turns/in (pitch = .25 in). If I want make a spring that has 3 turns/in (pitch = .333 in), can I make the spring by first winding it at 4 turns/in then plastically deforming (straining) it on the mandrel by stretching it out to 3 turns/in? Would I have to temper the spring wire to relieve any residual stresses?

Thanks,

P

The missing key information is mandrel diameter, wire diameter and material. For steel music wire of manageable size on a given mandrel, you can use a metal spacer that fits between adjacent coils to create the desired pitch of compression spring. The Hjorth and Advance Car Mover Porter spring winders use such spacers. Their spacers are much too thin to make three turns per inch, but the principle is the same.

Hjorth winders are antiques, found on eBay these days. Vintage HJORTH Perfection Spring Winder Collectible Tool ~ Pat' July 3, 197 | eBay

Porter spring winders are still made and work well for wire within their range. Porter Spring Winding Tools Utility Spring Winder

Larry
 
Hello,

I want a make spring that is beyond my lathe's capability to fabricate. The maximum number of turns I can make on my lathe is 4 turns/in (pitch = .25 in). If I want make a spring that has 3 turns/in (pitch = .333 in), can I make the spring by first winding it at 4 turns/in then plastically deforming (straining) it on the mandrel by stretching it out to 3 turns/in? Would I have to temper the spring wire to relieve any residual stresses?

Thanks,

P

I don't ordinarily HAVE to make any form of straight coil spring. Just select one.

Mostly weird variations of 'hairpin' or 'sort of, mostly' flat ones.

Even so, never, ever made one as I didn't use at least two steps of temper & draw heat treating, full equipment with good pyrometry, or jack-leg torch and 'make several, use the best one(s)' method.

If the pitch is not a match, go slower, use a floating 'tween coils spacer guide, and just manually hold tight to the guide as you wind.
 
Springs wound with hardened steel like music wire need to be stress relieved to get decent performance. To form the spring it must be stressed beyond the yield point or it would spring back to the original shape. That leaves areas stressed just below the yield point. When you stretch or compress the spring, some of those areas will go past yield and take a new shape. Therefore, the spring will not return to the same length. It doesn't take an especially high temperature. You can do it in your wife's kitchen oven while she is at a PTA meeting.

Bill
 








 
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