Hand Winding Torsion Springs

Hand winding torsion springs By prsxr

« on: May 10, 2009, 09:06:30 AM »

I've had a request to describe how to make some of the springs that I've used in my projects. So I made up a little how-to as I made up a low-power AR15 hammer spring for my Beretta 38a. This method will make double-sided torsion springs. I am told that the springs should probably be stress relieved after bending for maximum fatigue life. I have not done this, assuming my builds will not see thousands of rounds through them. If I have some break, I'd probably just re-make them. Spring wire is avaiable from McMaster-Carr (along with massive amount of other goodies-- *highly* recommended as a source) as assortments and 100pc quantities of 12" lengths.

The tool shown was made for doing the trigger and sear springs for my PPS FCG I was selling a while ago. The long rod is 1/4" diameter, (which determines the diameter of the spring loops) the small part is 3/16" dia (somewhat smaller than the width of the center part of the spring), with a reduced diameter shank to fit through the hole in the 1/4" rod. The length of the short piece determines the distance from the loops to the end of the spring. The end of the short piece has a dremeled slot in the end, with one side left long to resist the winding force, and the other leg shortened to allow the spring to be 'backed out' of the slot when the winding is finished. The two parts are assembled, and clamped in a vise with sufficient work area below the overhang. To begin, bend the length of spring wire in the middle with a pair of needle nose pliers to form the center square bend. Hook the square bend into the slot in the short piece of the tool. While pulling down slightly to keep the wire seated in the tool notch, bring the loose ends around slowly.

Try to keep the wires parallel, and tight against the previous loop. As you may see in the picture, I was not careful while taking pictures, and the far side of the spring has crossover in the loops. It will take practice to do the forming correctly. Continue coiling the ends until the spring is the way that you want it. When the spring is complete, it must be removed from the tool. Try to rotate the spring opposite the way you were coiling, and lift the wire out of the tool slot. This will allow you to remove the short rod of the tool from its hole, and then slide the completed spring off the end of the tool.

I have found some flexibility is possible in spring dimensions without making a new tool. The slot will accommodate greater widths of the square bend of the wire, but it does get harder to keep the spring symmetrical. If the coils need to be larger diameter, a bushing can be slipped over the tool. Wrapping with tape sometimes works with thinner wire. Hope this technique helps for projects where stock springs just won't do. As always, questions/comments are appreciated.