Tempering

[jellywerker]

There seems to be some confusion and lack of knowledge on these boards when it comes to tempering, so I am going to wirte a simple guide to explain it. I will not go into details that are unnecessary for lockpicks, so if you have more questions, pm me.

First off, tempering is the act of quenching (cooling) hot metal in a controlled way to change the properties of the metal, e.g.: brittle, stiff, soft, etc...

There are 3 main types of liquids that can be used for quenching, water, salt brine, or oil. For lockpicking you will need simple water, around room temperature. You will also need a way to spot heat metal to the correct color/temp. The simplest way to do this is with a gas torch. You want to hold the metal in the blue part of the flame (with pliers!), so it will heat fastest.

For tension wrenches (the main use for tempering in a lockpick set) you will want to heat the metal to a light cherry read (judge in a dark corner) and then quench in the water. When quenched at a light cherry red, the metal is stiff, but not brittle, and does not bend easily. I usually temper about 1/2 down the wrench from the bend, and the whole top part, to keep the small bend I add stiff.

Another thing that can be tempered on picks is the head+a bit of the shaft. I have done this to all my picks, heating them to full blue and quenching, making them stiff, but bendable so they are less likely to break.

2 last notes: 1. not all steel is temperable, although that used for lockpicks, being high carbon steel, usually is. You can tell the difference between high carbon steel and mild steel by it's sparks. High carbon steel will have lots of them, and they will be very bright. Mild steel will have about half as much, and they are usally more orange. Note 2: I am not responsible for you istempering your picks and having you end up with easy breaking brittle picks and wrenches. It takes a good eye and a bit of a feel for tempering to be able to judge it well, and you may not get it right the first time, so practice with some scraps first.

[Omikron]

That's some great info you posted there, thanks!

I do think that pictures would help though. Perhaps someone with ninja photo skills can take some pictures of the tempering process?

[ThE_MasteR]

I knew what tempering was, but always nice to have another guide

[illusion]

but always nice to have another guide

it's like having women in a harem - the more the merrier

[Shrub]

Sorry to put a downer on your guide but i dont agree with any of it!

You do not temper like that at all.

Tempering is also stress releiving, this is done after hardening to avoid the brittleness.

Hardening is heated to as bright a colour as you can, a high carbon steel like a hacksaw blade will get to a cherry red a low carbon steel will get to a bright orange.

Once at this state you then quench it, the material is now hard but brittle, to remove the brittleness you then temper the material.

To temper the material you heat gentally to a specific tempreture in the example of a hacksaw blade you would first clean the surafce to a shney one or colour free one and then gentally heat until it is a straw colour, a straw colour is a very good guestimate of the correct tempreture, you then quench the item.

All metalic materials CAN be hardened and tempered but each type involve differant tempretures.

In the case of a low carbon steel you would possably need to introduce extra carbon, this can be the roper stuff or simply dunking it in a pot of pencil lead crushed up,
You heat to the bright orange and then dunk it into the pot of carbon, you then reheat the material to a cherry red and you should see the carbon dissolving into the material, you then quench it, you then follow the above tempering process (on my post)

Sorry to wet your fire a little but things have to be right

[Shrub]

If useing wiper inserts or street bristles leave them alone, just bend them and use, if making picks dont get them too hot to begin with.

[digital_blue]

I have to say I concur with Shrub on this one. My own experiences have shown that heating to a cherry red and quenching will produce a brittle tool that is easily broken. Heating to a hacksaw blade (say, in a junior hacksaw blade intended for a tension wrench) to a straw color will give an optimum balance of strength and and rigidity.

This is a worthwhile thread for review:
viewtopic.php?t=6699&highlight=heat+treating

Cheers!

db

[jellywerker]

Interesting shrub, since I wrote from my experiences, the modern blacksmith, and some info from my dad (former farrier) but thanks for the material and corrections, shall I edit the post?

[Omikron]

Hmm, I don't think anyone here is a liar, but why the contradicting statements? Is there some variable X that we're not seeing here?

[n2oah]

Interesting shrub, since I wrote from my experiences, the modern blacksmith, and some info from my dad (former farrier) but thanks for the material and corrections, shall I edit the post?

Different strokes for different folks.
I'd be willing to be some of the city-slickers here don't know what a farrier is

[Chrispy]

it's like having women in a harem - the more the merrier

[Omikron]

ar·ri·er
n.

One who shoes horses.

[Illegal Inc.]

We're not all city-slickers when it comes to needing new shoes.

[vector40]

Maybe Shrub and jelly can offer what their personal expertise is so that we can compare the competing perspectives.

[Shrub]

I think in the manufacture of horseshoes you are working with a cast steel or if making from scratch you actually need the steel to be made to a brittle'er property than you would normally want from metal, they need to be hard wearing but it doesnt actually get banged a lot, you will notice that if a horse goes for a gallop on concrete or if they start bucking and stamping their feet, the shoes will all have to be changed and fracture lines evident.

The guide Db has pointed us to is a very good one that i havent seen before for some reason BUT he suggests waiting until the material turns a blueish before quenching on the annealing process which is too hot, a straw colour on the high carbon steel that picks are made from is the optimum state at which you should quench, the blue colour will make it a bit harder but also a bit brittler, there is only the differance of 1 second and 100-200' in that i think but its a differance non the less.

I get my experiance not only from metal working from a very young age (i was on a lathe at 10 and owned my own first one at 12) but from working on multi million pound goverment experiments for over 15 years.

I not only heat treated materials in that official role with flame and forge but also did very presise and controlled heating with proper electric powered machines.

Im not willing to turn this into a pissing contest, but needless to say i do know what im talking about when it comes to any type of metal work, plastic machineing or wood work.

Im not having a go by any means but no i dont think you should edit your post if you can but rather delete it as it could mislead anyone wanting to go down this route, you start by saying there is a lack of such posts but i have in the past gone in to depth about this and the link Db has provided was written this year, i think that guide should be sticky'd and this whole sorry thread deleted but thats not my call.

Im sorry if ive offended anyone out there its not my intention.