Patchbox springs

[Curt Larsen]

I installed an oval side opening patchbox (ala TVM) on my southern rifle.  TVM's set comes with a latch spring and a lid spring.  The TVM lid spring broke at the pre installed drill hole in it.  I tried to call TVM to get a replacement but all I got was the usual voicemail to leave a number etc.  I had a short  spring I got from TOW awhile back and tried that one with a messy burning oil temper method.  That one was too soft and didn't spring.  So I used another one of the short TOW ones I had on hand.  That one I took up to dull red and quenched in oil and relieved in the oven.  That one appeared stiff enough but it too broke at the pre drilled hole in it.  At this point I'm wondering what to do next.  This bloody spring is all I need to finish the project.  Any good thoughts?
Curt

[flehto]

I make all my Pbox springs out of purchased, soft spring steel {.015 thick} ...it's a high carbon steel and is heated to a slightly orange, red color and quenched in motor oil.  It's then polished and tempered to a light blue.gray color  by holding on a heated from below steel plate.  During the tempering, the spring is dunked in the oil to control the color. Special emphasis to get the correct color is made at the bends and drilled holes.  

This soft spring steel as purchased forms easily but the bends all have a radius...no sharp corners. These kinds of springs are easy to make and you'll have exactly what you want.....Fred

[rsells]

Curt,
I have been using the procedure that Ken Guy has in the tutorial section of the ALR with success.  It is under Tutorials, gunmaking tools and techniques-metal working, and banana patch box springs.  There is a bit of clean up with the procedure, but I have been successful the times I have used it.
                                                                              Roger Sells
            

[Jim Kibler]

Hard to know the shape of the spring, but it's a good idea to make a swell at any hole locations.  You don't want the cross section to be significantly less at any location.  If so, it will concentrate stress and could lead to breakage.

[KLMoors]

Hi Curt.

I have had good luck with the two thicknesses of spring steel that Muzzleloaders Builders Supply sells. I follow their instructions for tempering and they have worked fine for me.

[2veeps]

You might try calling TVM around 0900 CST while they are doing paperwork ( or whatever they do around that time). That's when I have had the best luck.  If not, leave a message about the spring and have them get back to you. By the time you try everything else, they might have a new one in the mail and half way to you.  Just a thought

  Veep

[Dave Dolliver]

For years I have been making small patch box and cap box springs from the metal banding that comes around my stock blanks from Dunlap.  It cuts easily with metal snips; bends without heating; and doesn't need any heat treat.  The deflection of the spring in this application is so small that the elastic limit is not exceeded.  Should I need a stronger spring, I use two thicknesses.

Try it.  Don't make the job harder than necessary.

Dave Dolliver

[Pete G.]

I'm with Dave D. on this one. I got a strap of banding from a lumber pile at Lowes. It is a lifetime supply and you can't beat the price.

BTW, if your springs are breaking they are not tempered enough.

[Curt Larsen]

Thanks guys for all the tips.  Ken Guy's tutorial was especially enlightening since he had the same springs as mine supplied with his banana patchbox. The lid spring he shows is the one that broke across the screw hole for me.  In my case, I have a side-opening oval shaped box lid so I'll have to use a small curved spring to contact the lid. I really like his use of hack saw blades and using the holes already in them.  I've got some steel banding that I will try too as well as the spring steel from MBS.  The last time I tried the oil tempering, I used a sardine can like Ken's.  Problem was that I lit it in front of our garage with the door open.  All of the smoke was sucked back into my shop that I share with my wife's jewelry making.  When I went back in it stunk like all get out.  I had to air it out quick before my wife had a project to work on.  Oh well, live and learn.  Next time the doors will be closed at least.
Thanks again,
Curt

[Herb]

I make patchbox springs from hacksaw blades, too.  Grind the teeth off, score a length, like 2", bend to break, flile the ends.  I don't use a spring but put mine under the finial, inlet flush to the wood, sticking out perhaps 1/2" with a slight bend down in the box and a 1/4" bend up at the tip to contact the lid.  when the lid finial is replaced, it holds the spring in place.  Doesn't take up any room in the box.   Can be bent cold.  When I make lid catch springs, I heat it red to make a square bend (L-shaped) and it doesn't need any tempering.  Or I make that bend without heat.  The teeth have to be all ground off, or else the bend will crack at a tooth notch.

[jerrywh]

 Springs that mount like that should not be allowed to flex at the screw hole. That should be prevented by a small plate that goes over that section and supports the weak section. another way to do it is with a large headed screw that fits tight against the spring.
 I make a lot of springs like that out of an old tape measure or a lawn mower recoil spring.  No matter what you make the spring out of it must be mounted correctly or you will have trouble.

[Herb]

Here is a hacksaw lid lifter spring.


And here is the hacksaw blade bent for a catch release spring.  The hook end was bent with heat, no re-tempering required.