Leaf spring making

[flatsguide]

Hi guys, I need to make a few springs like the frizzen spring and mainspring shown below. I’m guessing that the spring is filed to shape and polished before it is folded. How is the folding of the spring done so it has almost no gap on the inside bend and to minimize oxidation? Is it folded over a shim to maintain the thin space? Thanks for your help,
Cheers Richard

[smart dog]

Hi,
File and clean up what will be the inside of the bend.  It does not need to be polished.  Then heat red hot where you want the bend, hammer it to a right angle, then heat again and hammer it over into a full bend, then heat again and hammer the two leaves flat against each other.  You can heat them again and separate the leaves a little if you desire, no need for a shim.  To make a frizzen spring, use a strip of spring steel the thickness and a bit longer than you need and with a hacksaw, cut in from one side about 3/8" from the end the depth of the pin for the spring.  Then cut in from the other side at the same 3/8" distance from the end leaving a thin bit of metal still attached between the cuts.  Heat red hot and twist the tab at the end perpendicular to the rest of the spring.  That tab now forms a base on which to build up weld like a little Mt Fuji to form what will become the finial and bolster for the screw.  Then make the rest of the spring as you would any other V spring.

dave

[Clint]

I do use a shim as a spacer when bending springs, usually something like banding material or bandsaw blades. With the shim in place the spring can be hammered down flat and then opened back up to give the preload. when you open the spring, hold the bend, gently in a vise so the bend does'nt open up. For frizzen springs, I use steel that is thick enough to drill the fastening hole and draw hammer the leaf out on the end. File the spring to shape and drill a pilot hole while the spring is still on the bar, then cut it off, file the finial and bend it. Most people who are handy with metal can file a spring to shape and follow the directions for hardening etc. The critical part of spring making is the bend. Soft easy heat is the key. Too little heat will break the piece on the fly, while too much heat will break it in the hardening. Bright RED heat is what is needed not yellow. If you use a torch to heat keep the flame well away from the steel and let it heat slowly. A forge is the very best way to heat the steel.watch out for grabbing the spring in a cold vise, but rather make a clamp to hold the spring and heat it with the spring. I will take pictures of spring clamps and post them if you wish. Good luck and above all, have fun
CW

[rich pierce]

Clint and Dave, thanks for sharing your techniques. I seldom make springs but for frizzen springs, I like starting with big stock, tapering, drilling the pilot hole and bending before cutting the spring off the bar. No welder so I need to start with thick stock for the screw boss.

[smart dog]

Hi,
Using thick stock, particularly if the screw comes from the inside of the lock plate, is a slow way to go but works fine.

dave

[flatsguide]

I’ll second Rich’s appreciation of Dave and Clint’s description. Clint, I would really appreciate your posting of the tools you made for ease of spring making. When I start to make the springs I’ll post the journey here.
Thanks guys
Cheers Richard

[Bob Roller]

I used a different idea on V main and sear springs.The mainspring is first roughed out
on a bandsaw, I use annealed 1075 one eighth inch thick.Then the blank is brought to
width on a milling machine.The slot for the link or stirrup is cut at a specific predetermined
place at the long end of the blank.It is then fastened to a sine bar that determines the taper
and then placed in the milling machine vise and the taper is established wit a new 4 flute carbide
end mill @ 1000RPM and then taken to the bench vise and draw filed,polished and taken off the
sine bar and the "claw"is formed to match the link.I mark the place for the bend and using a
VERTICAL plate with a shallow slot the width of the spring I heat it red hot and bend it more
than 90 degrees then removed from the plate and reheated red hot and forged flat and while still hot the upper and lower leaf are aligned and a few fast cuts with a sharp file to make both the upper and lower leaf ARE aligned.The pin
that goes thru the lockplate is rough filed and then a short hit with a hollow mill doe the finish.
The upper leaf or limb of the spring is again determined by the milling machine and careful alignment with
the top edge of the mills vise.Again a few strokes with a smooth cut lathe file and another vertical spread
fixture and then reheat to red and tap the spring down and spread it and make small adjustments in the
curve of the lower limb to determine the preload the spring will have when hardened,tempered and installed.
This is MY way of doing this job and it's all I ever used and I know it works.
Scratch building a lock IS labor intensive and I stopped doing it in August of 2019.
Bob Roller

[flatsguide]

Bob, I was hoping you would pipe up and share your expertise...Thank you
Cheers Richard

[Rolf]

Bob, could you show a picture of the plate you use for marking and bending the mainspring.

Best regards
Rolf

[shifty]

I do use a shim as a spacer when bending springs, usually something like banding material or bandsaw blades. With the shim in place the spring can be hammered down flat and then opened back up to give the preload. when you open the spring, hold the bend, gently in a vise so the bend does'nt open up. For frizzen springs, I use steel that is thick enough to drill the fastening hole and draw hammer the leaf out on the end. File the spring to shape and drill a pilot hole while the spring is still on the bar, then cut it off, file the finial and bend it. Most people who are handy with metal can file a spring to shape and follow the directions for hardening etc. The critical part of spring making is the bend. Soft easy heat is the key. Too little heat will break the piece on the fly, while too much heat will break it in the hardening. Bright RED heat is what is needed not yellow. If you use a torch to heat keep the flame well away from the steel and let it heat slowly. A forge is the very best way to heat the steel.watch out for grabbing the spring in a cold vise, but rather make a clamp to hold the spring and heat it with the spring. I will take pictures of spring clamps and post them if you wish. Good luck and above all, have fun
CW

    Clint, would you post the pictures of the spring clamps you use please.

[Clint]

here is a picture of two bending guides made up for sear springs. The guides are made from 1/4" x 1/2' and 3/8" x 3/8" steel. The hole is drilled after the bend and the distance from the center of the hole to the inside bend is cut to a very close measurment. The jig will hold the straight spring pretty firmly so you can heat the whole thing and bend the spring. The jig will keep the heat for the spring and as long as you don't get too rough, it won't deform at heat. The idea is to simply to bend the spring exactly where you want, not so much to form the exact preset. That can be done after the spring is bent and squared up.

 
As a side bar, you may notice that antique springs are considerably thicker at the bend than on the leaves. The suggestion here is that the steel was bent from a thicker piece of steel, then the leaves were filed down to their final dimension.

[rich pierce]

Very cool. Thanks, Clint!

[flatsguide]

Clint, thanks so much for sharing. What a simple fixture...but simple and effective is real clever.
Again thanks Clint.
Cheers Richard

[shifty]

   Thanks Clint !

[Bob Roller]

If possible I will have a picture of my sear spring fixture.
It is adjustable with a small screw for different lengths.
Bob Roller

[shifty]

If possible I will have a picture of my sear spring fixture.
It is adjustable with a small screw for different lengths.
Bob Roller

  That would be great!

[flatsguide]

Bob, I Would like to see your sear spring jig.
Thanks Richard