The inspiration for this tool came out of necessity. I have had such trouble with large powerful lock springs, and I did not possess a standard tool with enough reach to safely remove the mainsprings.
The body is 1018 steel, casehardened. Fully 3/8 thick, the tool is robust. It has relief notches cut on both sides to slip under the bolsters of both left and right handed locks. The screw is case hardened and has a swivel foot to conform to the angle of the mainspring.
This tool does not work well on medium sized or small locks. But for the large locks, it’s a time (and replacement spring) saver, and takes the worry out of removing those difficult mainsprings.
WARNING: anytime you work with these lock springs, you MUST wear safety glasses. Protect yourself!
To take a spring off a lock, first place the lock on half cock. Then locate the compressor over the elbow of the spring. The deep narrow notch is for slimmer profile springs like the Early Ketland, or the Twigg. The next notch fits the Davis Early Colonial, Jaeger, and other heavily proportioned springs.
Put lock on half cock
With the compressor over the elbow of the spring, make sure the clamp is sitting on the flat arm of the spring, not up on the tab for retaining the spring. That might cause the clamp to slip once pressure starts to build.
note position of clamp on elbow
Then tighten up the screw until it contacts the toe of the spring. make minor adjustments to the position of the spring. Make the body of the clamp as parallel with the lock plate as possible. Once your position is good, tighten the screw until the mainspring hook is off the tumbler. Always watch the tip of the screw that it is not walking off the end of the spring as you turn the screw. Some springs have casting lines which cause uneven seating of the clamp. Stone or file those features down flat. Note that the compressor supports the spring way out near the hook.
tighten screw and position clamp carefully
Lower the hammer. Try to remove the spring. If there is not enough wiggle room, tighten the clamp a little more. Tighten ONLY enough so you can work the spring out of the lockplate.
Use as little compression as possible on the spring.
Lift spring carefully out of the lock.
Spring is out...and still dangerous!
Carefully unscrew the clamp to release pressure. Keep a close eye on the screwtip so that it does not slide off while you are relieving the pressure on the spring. I recommend wearing a leather glove on your left hand while unscrewing with your right.
Carefully release the spring.
A second hole for a frizzen spring compressor is tapped closer to the elbow. Just unscrew from the outboard hole to the inboard one.
A frizzen spring compressor!
Some of the locks I’ve used the compressor on:
Davis Germanic and Twigg, Early Colonial, Lott, Chambers Early Ketland are some examples
These vises are available from me for $60 USD, plus $5 shipping within the continental US. Personal check or money order for $65, sent to Tom Curran, 1 Center St., Chatham, NY 12037 Eight percent sales tax applicable to sales within NYS.
