Author Topic: Lock plate tempering  (Read 4346 times)

tuffy

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Lock plate tempering
« on: April 05, 2014, 03:36:50 AM »
I'm sure this has been asked a number of times but I couldn't find it in the archives. What do I need to do to keep my lock plate from warping when I anneal it for drilling and tapping? If I need to build a jig for it does anyone have a photo? Thanks in advance.

     CW

Offline KLMoors

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Re: Lock plate tempering
« Reply #1 on: April 05, 2014, 04:24:11 AM »
Are you sure it has been hardened? If so, is it just cased hardened? Most of the time, you don't need to anneal it.

tuffy

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Re: Lock plate tempering
« Reply #2 on: April 05, 2014, 05:00:04 AM »
Yes, it is case hardened.

          CW

Offline Acer Saccharum

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Re: Lock plate tempering
« Reply #3 on: April 05, 2014, 05:20:45 AM »
If you can, grind a spot with a dremel to get below the case into soft material.
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Offline James Wilson Everett

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Re: Lock plate tempering
« Reply #4 on: April 05, 2014, 08:57:33 AM »
Dogface,

Don't anneal the plate, just stress relieve it.  In anneal you heat the metal to above the transition temperature and allow to slow cool, usually bright orange hot. This oftens brings a risk of damage to the metal grain structure and warping.  To stress relieve, just heat to above the temper color blue, like where the metal turns grey, or at most to a very dull red in a dark room and allow to slow cool.  Now the metal is soft enough to cut, drill & tap, but it does not risk the warp as you get with a full anneal.  I try to avoid heating any steel to above the transition temperature, orange hot - 1500F - where a magnet will no longer stick to iron, for any shaping, bending, forging.  I only get the metal orange hot for the final hardening step for springs, frizzens, and case hardened parts, and then only for a short period of time only.

I hope this helps,
Jim
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Offline LRB

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Re: Lock plate tempering
« Reply #5 on: April 05, 2014, 01:23:39 PM »
  Why would a lock plate be case hardened before it has been drilled and tapped for the internals, or are you doing a modification of some sort?

tuffy

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Re: Lock plate tempering
« Reply #6 on: April 05, 2014, 09:20:38 PM »
Thanks guys. I think I'll just do as Acer has suggested.

LRB... I'm new at the game and kind of over looked it before I had the lock case hardened. A first timer mistake. Although that isn't the only one. ;D

               CW

Offline LRB

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Re: Lock plate tempering
« Reply #7 on: April 06, 2014, 01:04:57 PM »
  Well, learning by mistakes is not the best way to learn a lesson, but it often insures that the lesson will not be soon forgotten.    ;D

Offline Dphariss

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Re: Lock plate tempering
« Reply #8 on: April 06, 2014, 04:21:39 PM »
Yes, it is case hardened.

          CW

It need not be fully annealed. Polish and heat to a the silver or grey color, the color after light blue. This should allow it to be drilled. Or even better get a carbide drill it will cut casehardening like a hot knife through butter. If you have a drill press.

Dan
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Offline Old Ford2

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Re: Lock plate tempering
« Reply #9 on: April 06, 2014, 04:23:31 PM »
Hi,
One way to soft anneal case hardening is to spot heat with a copper or brass rod ( the size of the hole you wish to anneal ) and a battery or arc welder.
Put booster cable ground to the metal, then carefully touch the spot with the brass or copper rod held by the positive lead.
That spot will turn red very quickly, and yet not distort the rest of the metal.
Dan's suggestion with a carbide bit is very good, if it is a small bit, be sure to use good lube, or you have a good chance of breaking the bit.
Fred
« Last Edit: April 06, 2014, 04:26:49 PM by Old Ford2 »
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Offline FDR

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Re: Lock plate tempering
« Reply #10 on: April 06, 2014, 09:56:13 PM »
X2 to what Fred said.  I was taught to use the carbon rod from the center of a dry cell battery (size "C" or "D" size, sharpened to a point) as the electrode.  Works!

the other :
"Fred"