Proper way to heat treat homemade picks

[Omikron]

Dry, not sure if your still around but i think when annealing to wait until the material is blueish is too late! You need to go for a straw colour

Otherwise great guide.

So would Mr. Shrub approve of this guide as a valid one, then?

[Shrub]

Otherwise great guide.

[Omikron]

Otherwise great guide.

Mmm..point taken.

[scampdog]

when tempering,a good way to achieve an overall straw colour,is to make a heat sink,simply use a piece of thin sheet metal about 2mm will be ok,big enough to place the whole pick on.apply your heat source underneath the plate,the heat will then be transferred evenly from the plate to the pick, at a nice steady rate, allowing you to clearly see the change in colour.

[krept]

one thing I have found that might help...

using color as a guide is difficult, especially if you are working in daylight. What bladesmiths usually do when they perform heat treatment on blades is use one of those telescoping magnets available at places like Home Depot.

When you heat the steel to nonmagnetic (when a magnet will no longer stick to it) the carbon in the steel is properly dissolving into the iron matrix. Usually with 1/8" thick steel or greater, this requires "soaking" the steel for a couple minutes or longer depending on the thickness. With picks, I don't think it is that critical.

To anneal, or soften, the steel, smiths often use vermiculite... it's a compound found in the gardening section of home depot... kind of like a golden flaky material. It's useful because it insulates very, very well. The steel is heated to nonmagnetic and then buried, packed as tightly as possible, in the vermiculite. For blades, it usually takes overnight to cool to room temperature.

For heat treating of simple carbon steels, oil is probably better because water has cracked many blades.

For tempering, many people use a toaster oven (with a door and dial) or their kitchen oven. What is important if you are interested in obtaining a specific rockwell is heating at a given temperature for a given period of time. Because ovens vary, a cooking thermometer is useful. Heat treat charts are available online, but for simplicity sake... a straw color as mentioned above is a good rule of thumb.

again, just a couple comments from a different perspective. As written, the guide gives a great foundation.

cheers

[illusion]

Hmmm if you can crack a pick by hardening it you have done something fundementaly wrong... When making katanas for instance there is a chance that the sword will break after you apply clay to each side of the blade to curve it, bit I doubt such a circumstance would ever happen to a pick due to less heat needed - this is the only time I've known a blade to crack upon touching the coolent.

When steel gets hot enough it ceases to be magnetic, this is correct, but you shouldn't be heating your picks to a temperature that causes this...

I anneal picks by merely heating them and leaving them to cool - this has served me well, but perhaps there is a better way.

[krept]

when steel is left to cool at room temperature in open air, it's usually called "normalizing" which reduces the stress and serves to refine grain structure. Normalized steel will be softer than heat treated steel, but also harder than it would be in the annealed state. At these thicknesses, however, it's probably a moot point.

Again, I was just going off of my experiences in knifemaking... simple carbon steels require a VERY quick (like one second) of time to get from critical (nonmagnetic) to around 900F IIRC, which will trap the maximum amount of carbon in the iron. Not reaching critical and not cooling as quickly will result in a blade that is not as hard as it can get, but again... probably good enough for the purposes involved with a pick.

Water heated to 160ish is good because the heat doesn't allow the water to gas off AS quickly and form a steam envelope as it would with room temperature water. Same goes with oil, ideally, but oil allows for a much slower curve.

When quenching, water frequently will fracture steel where there are small stress points. I would think that this would be accentuated with thinner pieces of metal, but perhaps not?

Blades are coated with clay because the clay acts to insulate the area that is coated... i.e. when the edge reaches nonmagnetic, the spine will be below critical and when quenched the edge hardens and the spine is left harder, tougher. The curvature of katanas results because the edge, when cooling, grows more than the spine. This is where the steel is frequently killed.

[Shrub]

Ive covered this with another member who makes swords and the like, blade making is slightly differant to simply hardening a material and although a blade can easily shatter in a quenching process the simple hardening of a pick or such like is not going to produce problems.
A blade shatters due to stresses in the material that are built up with working it and the shapes they are made to.

To heat to a de-magnitised state is too hot for general hardening of hacksaw blades and can be hard to gauge depending on magnet strength and surface finish (along with material type of course) the straw colour is easy to see and actually quite accurite.

Colour, smell, taste, feel and cutting ability are all ways of telling how hard a steel but when worked all these properties change and you have to rely on known constants and for one the colour is the most accurite without getting the hardness testers out and heat controlled ovens.

You mention a couple of fair points but they are more to blade manufature than general hardneing which is less scientific.

Illusion, feel the force ive obviously taught you well

[Shrub]

Just to add as youve posted i the middle lol
Letting cool in air is tempering, normaliseing, de-stressing etc etc any which way you call it its the gental cool of the material that counts, quenching in anything no matter how hot it is only prolongs the process and doesnt achieve anything more than giving you a slightly harder surface than air cooling, you dont air cool blades as yes they can be made too soft to work well but as i say blades are an entirley differant process.

Clay was used when the heat was wanted to be high but the extra carbon from the fire wasnt wanted also it keeps a more uniform tempreture around the edge which becomes very fragile as soon as you start heating it.

You undoubtdly have good success in makeing blades and know your stuff but go back to your simple mertalagy processes and forget the blades aspect as they are 2 very differant subjects.

[illusion]

Yeah, the spine is coated with a thick layer, and the blade is covered with a thinner layer. When heated the two parts cool at different speeds, and the blade curves because of this. The spine will become Pealite, and the blade Austernite - this gives a good balance between the rigidness of the Austernite, and the softness of the Pearlite.

I would LOVE to have the oppertunity to forge my own Katana some day - it's something I've seen done first-hand, and has left a deep impression.

A good discussion.

[Shrub]

Sword making and such like is a great skill to even do half decent, i could make a blade if i needed to but it wouldnt be anywhere near as good as an apprentice's one.

Ive seen it as well once and it is an art, it can take days and weeks to produce the bigger types and the only way you know they are any good is after the last polishing and then trial, when they were made for use in the asian parts of the world they used to line a row of men up and see how many of them it would slice through before the momentum or the blade stopped cutting them, a 5 man sword was much better than a 2 man sword.

I sold my forge to someone who was being taught the procsses and i have an open invite to go and have a go sometime, im waiting 12 months or so before i do so hell have a better idea then ill go and see if i can learn any new tricks.

[krept]

thanks for the input. I've never tried heat treating anything other than blades, so sharing your understanding and experience is appreciated.

i found that in the simple steels that i work with, when the shadows leave the steel and it begins to glow dull red, this is when it approaches nonmagnetic. it sounds very similar to the color that was described, but then again, i'm working with stuff that is many times thicker... and I don't know if hacksaw blades have different properties than 1080 or 1095.

thanks again!

[krept]

re: katanas...

Wally Hayes (http://hayesknives.com/menu.html) makes some awesome stuff. He's also got some videos out that show the process of him making the katanas.

http://technicalvideorental.com/ rents that video (gotta get that, much better than buying it IMO). Just noticed they have two vids about lockpicking too... pretty cool stuff.

as far as the forge, mine is a simple design using an empty freon tank... got the design from Ron Reil, although his page appears to be down now.

cheers

[illusion]

Thanks for that.

He has some cool stuff, and it might be worth trying to find the videos he has made.

I like the Wu Jian he did - pretty neat.

[Shrub]

i found that in the simple steels that i work with, when the shadows leave the steel and it begins to glow dull red, this is when it approaches nonmagnetic.

Thats way too hot then, the straw colour state is quite cool in comparison and on thin stuff like hacksaw blades you can pick it up as soon as youve put the torch down (DONT try it kids)