Bridge Plate Removal Chisel

[Eric A. Danser]

Hi all, I'm attempting to make a bridge plate removal chisel a la frank ford's.  I ground an old hard file into a chisel but it snapped when I tried to bend it.  I obviously need to add heat but was wondering if anyone had any tips on how hot to get the metal in order to bend and the best way to do it.  Any help would be much appreciated.  Thanks.

Andy

[Ned Knepp]

Eric, I haven't got the hang of softening a file enough to bend then re-tempering it either. I have a bridge plate chisel (?) that started life as a long screw driver. It had to be heated to make the bends but it is plenty strong as it is now. The blade may be a bit narrow but it does the job.

The "blade has been ground flat and the end is sharpened like a chisel blade upside down, that is with the flat side "up" and the bevel toward the inside of the angles. In retrospect it may have been a bit better if the blade was a little longer but it works just fine as long as I get the plate plenty hot and I "finesse" it off rather than trying to jerk it off in one go.

Ned

[Eric A. Danser]

Thanks for the info Ned. Did you just heat the shaft of the driver with a blow torch until it was red hot and then bend? I wonder if it is possible to bend a screwdriver without heat? Thanks again.

[Grahame Myers]

You need to heat it up till it's cherry red (that's what they called it when I learnt my trade way back in the last century :-)
To bend it, the best way would be to use a round bar clamped in a vise as a former, or the round horn on an anvil. Don't let it cool too much during the bending, keep it at cherry red by re-heating until it's bent to shape. When you're finished with bending, heat it up again to cherry red, and then plunge it into a bucket of oil (you can use old oil to save money) to temper it. Buff it up a bit, and you're good to go. Have fun with it.

Grahame

[Howard Klepper]

That will harden it. Tempering is another step.

[Grahame Myers]

Howard
You're right of course about the difference between hardening and tempering, I was having a senior moment, lol

Grahame

[Murray MacLeod]

To bend an old file into a U-shape like that is a job for a blacksmith's forge, ideally.

You need to get the metal red-hot, you could conceivably do it with a blowtorch and a vise, but a forge and anvil is by far the best way.

[Ned Knepp]

As Grahame said it was heated to cherry red ( in the area of the bend) with a torch. I suppose it might be possible to bend it by hammering it into shape but I would definitely avoid any sharp turns. The corners would fatigue and probably fracture if you didn't break it outright. If you have access to an anvil or some other rounded, heavy steel it should be possible to hammer it into a curve. I strongly recommend that you heat it and bend it. I think you will have much less trouble keeping the blade straight with the handle and it would be much easier than beating it into shape cold.

I heated mine and locked it in a big bench vice to bend it (thus the square corners on the inside of the bends). Make the bend in the tip first. I did it in a vise because I just couldn't think of a way to grip it well enough to bend it around a pipe. I dropped it into a buck of water to quenched it. It's not nearly as hard as a file but it's not as brittle either. It won't take a razor sharp edge but I don't need it to do that. The edge is will take is sharp enough for my purposes.

[Frank Ford]

Not to worry - it's an easy bend with pliers when the steel is red hot in the area. If you want to restore hardness, you can heat the chisel tip ONLY to bright red and quench in water. Then bake it in your kitchen oven for an hour at 400F, and you'll draw the temper nicely for chisel use.

As to strength, were simply not putting much strain on these things, so I doubt that would be an issue.