When DH made me some springs for a bobbin winder and a leg spring for my FW table, it was at 500F for about an hour. This was from a couple of forums he found online about making springs. It's a memory exercise for the metal. It actually rearranges the molecules to a degree.

I also think that your spring might not need to be shortened, but instead "rewound" and then adjusted based on the new position that the "Eye" ends up at. It's likely that it was unraveled when someone yanked thread out of it too hard and the wrong way.

Lengthening the stitch might help it feed better. The knob just above and behind the shuttle winder is the stitch length knob. I worked on one just like it on Monday. The couple paid $120 for it, but the check spring was broken. I got it sewing, but the stitch quality wasn't the best without that check spring.

Thanks for that link Tammi. I saved it to my computer.
Rodney

Spring comment:

Steel is an amazing alloy. Yes, it is an alloy of Iron and carbon.

Because you can change it's properties through controlling the temperature you can make it into amazing things like springs. People who do this use terms like "Spring tension" which leads to terms like "relaxing the metal" (removing tension ya know)

I teach a class in metal working and part of the class is taking three pieces of 1050 Steel (most common antique hardenable steel alloy) and do the following:

Piece 1: Heat to orange color, then put into a bucket of fine sand
Piece 2: Heat to orange color, then quench in water.
Piece 3: Heat to orange color, quench, then reheat to dull cherry color, then re-quench in water.

After about 15 minutes (to let the sand quenched bit cool) we take out all three and try to fold them in half.

Piece 1: Folds easily and retains the bend when released
Piece 2: Breaks/Shatters when bent too far(sounds like glass when it does)
Piece 3: Bends and then springs back to it's original shape.

NOTE: Copper and Brass are the exact opposite of steel. Heating and quenching it softens the metal, while heating it and letting it cool slowly hardens it. (can make brass brittle enough to snap when bent)

Great information Steve. Thanks for sharing your expertise

no problem, hope it was not to "lecturey"

I forgot to mention that one of the other posters asked what temp, but that changes based on the alloy. The COLOR however does not. most metal workers use color as the key to temp control (even the professional hardening shop across the street from my work)

Tammi so DH made FW table springs? Good idea, I'll give it a go!

So in order to get the proper spring I need to follow instruction 3?

correctamundo

Yep! That and a bobbin winder spring for a 99- or 115 that was discontinued. I think it took him about 4 or 5 tries to get the coil the right size, and it was a little "stronger" than the original, which just meant having to push the winder down a little harder.

The table spring was way easier because a good portion of it is straight already. One try, and I might have a spare here somewhere, and all of the springs were out of maybe 1 or 2 pieces of music wire.