Tool steel

[Mark Baldwin III]

I have been wanting to make a few of my own edge tools for a while now. Over the last few days I machined a mortise chisel from A2. From what reading I did, I thought I would be able to harden it by heating to red with a torch and letting it cool...then tempering at 400 degrees. However, this didn't work. I reheated it, and quenched it oil...again tempering at 400 degrees. This didn't work either. Now, I'm digging a little deeper, and I've found at least 6 different methods for hardening A2.
So, my real question: Should I switch to a different tool steel? I'm only out about $20 if I can't make this particular piece work, so I'm not worried. But I'd like to make a few chisels, and several plane irons. What would be best to use?
I have access to oxy-acetylene torches, and a small kiln that can do 1600 degrees.
Thanks in advance for any help!!!

[Steve Kirincich]

You may want to try O1 steel. This is an oil hardening alloy. A2 is an air hardening alloy.

Steve

[Ryan Baker]

Yeah, start with O1. A2 is much more difficult to properly harden/temper. You also need to make sure you are getting it heated enough to harden in the first place.

[Steve knight]

a2 needs to get far hotter then your touch can get. once it reaches the right temp it is cooled in the air. it takes a lot of skill to heat treat it well. usually it needs to be done by a heat treating shop to be done well.

[Johnny Kleso]

I have a heat treating page at my website bottom..

like others said A2 has to get to 1750º where 01 is only 1500º

Coal/Air fire gets to 2100º but 01 is more forgiving than A2..


Here is a good link on temps..
http://www.blksmth.com/heat_treat_guide.htm
one day I will up day my page :)

[Jay Rasmussen]

If you want to stay with A-2 you might see if you can find a local Injection Mold shop or die shop. If there nice guys they would probably do your stuff when doing parts of there own for a small charge. Very easy if you have the right oven.

[george wilson]

I use A2 a lot. You apparently haven't researched how to harden it. First of all,it does harden at a higher temp as mentioned above. Just as important,it MUST be wrapped in stainless steel heat treating foil, or it will develop a SOFT SKIN up to 1/32" deep( on average.) It is air cooled. You are lucky it didn't crack when quenching it in oil. I don't know if you have ruined it already by heating in open air.

Heat treating needs to be done ACCURATELY in a furnace with a pyrometer control on it. There is ONLY about a 25º WINDOW of accuracy to get the best performance out of a tool steel,especially the more sophisticated ones like A2.

After hardening,the part is BEST tempered just as it gets barely cool enough to hold briefly in your hand. This is about 140º.

then,it must be popped right into an oven pre heated to 400º,or whatever temperature is recommended. I keep a toaster oven with an ACCURATE Brownell's high temp. thermometer in it.

My furnace is an electric knife maker's furnace with accurate pyrometric control.

You should get some 01 and use it until you get proper equipment. It is much more forgiving. Heat the 01 to ORANGE,and quench in vegetable oil or automatic transmission fluid. The quench must be big enough that it isn't heated by the tool,or it may not harden the tool. Polish off a surface,and carefully heat it to a brown color for a plane iron. Even a bit of purple or blue doesn't hurt 01.

[Mark Baldwin III]

Thanks guys. It's looking like A2 was not the right choice for my capabilities. From what I've seen on O1, I should be able to torch it up to red, then quench it in oil, then temper it? If that is the basic idea, I will switch to O1. I only purchased one piece of A2, as I haven't done this before, I didn't want to spend a bunch of cash to find out I couldn't treat it myself.
So...if I decided I wanted to make some 1/4" thick plane irons from O1, is it something you think I should be able to handle?
The main reason for this is that I really can't afford to buy some of the edge tools that I want, so I'd like to learn to make them. $30 for the material to make 3 irons for myself is a lot less than $40 each for the irons I want.

[Mark Baldwin III]

George...you are right...I didn't do the right research. I thought I did, but when I went back trying to figure out what I did wrong, I found that I did everything wrong. Thankfully this is only costing me $20 and some time. I've made costlier mistakes! :D

[george wilson]

HEAT TO ORANGE,not RED. You need to take a bunch of DRY bricks,and make a brick base with other bricks arranged into a corner. It will trap heat MUCH better,and 1/4" will take a LOT of heat. I recommend you use 2 MAPP gas torches. I don't think 1 will get the steel hot enough. It could for 1/8",but not for 1/4". You should be able to get 2" of the plane blade orange. I recommend AT LEAST a gallon of oil.

DO NOT try to get by with USED MOTOR oil. You will get aTHICK coating of black carbon that is MURDER to get off. It is REAL hard.

DO NOT bevel the irons before hardening. You will guarantee a warp across the iron which will be BAD to try to flatten. This is from 2 different size surface areas on either side of the blade. One will cool faster,and invariably warp the blade.

DO NOT heat until the surface of the steel begins to "peel "off. If you get blisters on the steel,it has been over heated and burnt. Soon as it goes from blood red to orange,quench it,and don't push your luck.

If you have a magnet you can mount on a coat hanger wire, quench the steel as soon as it becomes non magnetic. Don't let the magnet get too hot,or it will de magnetize. Don't try to use rubberized magnets.

[David Weaver]

DO NOT try to get by with USED MOTOR oil. You will get aTHICK coating of black carbon that is MURDER to get off. It is REAL hard.


Not to mention that used motor oil is a known carcinogen. Vegetable oil only has to be bought once - it's worth doing.

[george wilson]

We kept a5 gallon bucket of auto. transmission fluid where I worked. By the way,EXPECT it to catch fire a bit when you quench a largish tool. No biggie.The fire will snuff out as soon as the hot part is submerged. Best not to do it in a finished,painted room. It will make soot. Keep your face to the side,and DOWN,NOT overhead of the quench,unless you want a black 5:00 shadow on your face.

To make a brine quench, use distilled water if possible,and dissolve ICE CREAM salt in it till a potato will float. This is ONLY for water hardening steel. Distilled water is best because tap water has unknown minerals in it. Not sure why ice cream salt is best,but it is recommended.

[Rick Markham]

Pay close attention to George! (take notes) I did... Here is one blade I just finished, 1/4" thick O1 tool steel, it's wicked sharp too ;) Hopefully this "Christmas break" at school, I will get the plane finished... it's functional at this point, but not refined yet.

http://img.photobucket.com/albums/v295/Rick357/005-6.jpg

[James Baker SD]

Amazing the things you can learn on this forum. This amount of experience willing to be shared is unbelievable.

[Johnny Kleso]

What kind of torch are you using?
I hope not Mapp, you will need oxy/acc if you want it hot enough..

When heating the steel look for a cherry red color just after orange..
How you can test you are at the correct hottness?
Use a magnet and if it doesnt stick your at the corret temp..
This is calld the curie point..
Do not over heat the magnet or it will not stick to anything..

Also you oil must be per-heated to 200º if I remember right
The steel can crack if to cold.
I just heat some scrap steel and quench it before I heat any blades..

Also you maybe able to use the A2 you tried, I am thinking its never got hot enough..
If you try heat treating more than twice you risk burning off to much carbon to do it the thrird time..
If you never made it hot enought I think you will be good..

[Russell Sansom]

Mark,
You will probably benefit highly from "the backyard blacksmith." I think that was the good one. Many of us didn't have George decades ago and were still able to muddle through. There's an entire book full of pictures, concepts, and details ... which will save you a good deal of trial and error and help you develop an eye for various steels. BTW, You can get pretty good heat out of coal and forced air. I started with a hibachi and an old-fashioned portable hair dryer.

[Mark Baldwin III]

Thanks again guys! The amount of knowledge here is awesome!!! Stop me or yell at me when I go wrong here:
1: use O1
2: DON'T cut the bevel before heat treating
3: Heat to ORANGE...I have oxy-acetylene, much hotter than MAPP
4: Check with a magnet, luckily, I've got a bunch of 'em
5: Quench in a large quantity of oil
6: Temper when the blank reaches about 140-150 degrees
7: Grind, sharpen, enjoy my new iron

on tempering...it looks like 400 is my target temperature. My kiln doesn't have a sight glass to judge color. I've seen the rough rule of at least 1 hour for every inch of thickness. Does that mean I should be OK with 15-30 minutes in the kiln? Double temper...basically, I am to allow it cool, and put it back in at 400 degrees?

I hope I'm not asking too many stupid questions here. I'll have a look around for that book too.

[george wilson]

Temper when you can BARELY manage to hold the iron in your hand for a time long enough to get it into the toaster oven.

As for double tempering,the second temper should be done at 25º LESS than the first temper.

Your double temper accomplishes nothing if you only temper it at the same temperature.. Go to Victor machinery and look at their catalog. They sell ONE little blue book by Suzerma(sp????) I had that book at work. It is a small book,and not real expensive. It is the BEST book on heat treating I have ever had. I need to get myself a new copy. It is the only book that ever said that getting the part into the tempering oven at 140º was critical to the life of the tool.

Of course,he was talking about expensive dies for stamping metal parts by the thousands,not a plane iron,but still good advice to heed to get the most out of your tool. Tell them George Wilson sent you.

[Rick Markham]

Don't grind a bevel until after the process is over, it will help prevent warping. There are knife makers that swear you can, there is a process called "normalizing" that you can do before heat treating to help minimize warping. I didn't use that. Just so ya know, it takes quite a bit of work grinding the bevel on a 1/4" plane iron initially ;)

O1 is pretty friendly to the tool maker, There is lots of info on the net from industry books that give you more details than you need. I need to get a copy of the book that George recommended, I'm sure it is worth it's weight in gold.

Do you have a kiln? If you have an accurate pyrometer you don't have to see the steel, just trust the pyrometer. You need to make sure your oven (or toaster oven) is accurate, I have a digital thermometer with a separate probe that I have used for sugar work for years. (mine is expensive, but you can get really accurate digital thermometers with a probe at Cooking stores now for about $20 I use that to insure the accuracy of my oven's thermostat. (my oven is actually extremely accurate)

George, after doing this blade, I realize I need to get a controller for my kiln. I knew I was in for alot of tinkering with the dial from what you had told me, and sure enough, it was a hands on job. I will be investing in a controller soon. Any suggestions from your experience?

[Zach Dillinger]

Rock Hock has a nice primer on DIY heat treating at his website. http://hocktools.com/diyht.htm

[george wilson]

Rick,I got my knife maker's furnace from Koval knife co. Koval died,and I don't know if they are still in business. Mine wasn't the least expensive model. it is 22" deep. Can't recall the name right off. Years ago it was about $900.00. I don't know if they sell separate control unit add-ons or not. Our old one at the shop had simple analog controls. This one at home has a computer controlled unit on it I could well do without.

[Jim Koepke]

Thankfully this is only costing me $20 and some time. I've made costlier mistakes! :D

$20 is an inexpensive education!

jtk

[Johnny Kleso]

1 Gal. can or clay flower pot works well you can also use a brake drum from a car or truck for a coal fire..

With your torch the clay pot might work well holding heat..

Quench the steel straight into the oil or it may warp going in sideways..

[Mark Baldwin III]

Thanks for the tip on Victor machinery, George. They have quite a bit of stuff that I've been looking for, and at better prices than I've seen anywhere else. I'll have to tell my R&D guys at work about that, they'll flip at some of the prices!

[george wilson]

Not EVERYTHING they sell is great,Mark. I recommend their tool steel,though.

I bought a big stack of OLD Brown and Sharpe W1 steel,all 6" wide that must be at least 50 or more years old. Maybe 80 years old. The paper wrappers were falling apart. They thought the condition of the wrappers might irk some customers,which I am sure is true. to me,it was a treasure trove of GOOD OLD AMERICAN tool steel. The grind on that steel is many times smoother than you get today. I have made some nice blades with it!!:)

It is getting VERY difficult to get W1 anywhere,anymore. I guess most steel makers consider W1 as too old fashioned. And,it IS treacherous for making dies out of,from cracking,warping,and slightly changing size a few thousanths of an inch when hardened. I have used it for dies,and it IS risky. We bought several hundred antique jeweler's dies made from W1. They are very risky to harden. They used to harden the dies,leave the punches soft,and peen the punches,and squeeze them through the dies to re sharpen them. I want BOTH hardened. These type dies were for a certain class of very thin brass trinkets made probably about WWI.

Of course,their regular steel is new stock. English made,I believe,and they do sell it cheaper than most anyone. Probably their milling cutters are Chinese ( unless otherwise stated). Anyway,I've been there about 4 times,and they have been good to me.

[Johnny Kleso]

Mark,
I just checked Enco and they have the same prices BUT if you join there email list you get a free shipping code for orders over $25 or $50 and under 100 lbs depending on offer that month.

Its hard to beat Enco with shipping raw Starrett or Made in USA stock for free

http://www.use-enco.com/CGI/INSRAR?PMSECT=0000000793

[george wilson]

Enco is hard to beat on prices. I hadn't compared their prices lately. I have so much tool steel on hand it will probably last for many years.

A few years I went to the junk yard. They had a WHOLE PALLET full of 01 tool steel neatly stacked about 5" deep. Someone just eliminated their inventory,or closed up shop. Needless to say,I bought most of it for .20 a pound(or whatever scrap steel price was.) That,and the old Victor metal,and what I already had on hand amounts to a few hundred pounds of tool steel,possibly more. Then,a few tons of other steel,brass,and aluminum.

[Mark Baldwin III]

I bought my 0-3" mic set from Enco when I was in high school. I was the first kid on my block with my own set of mics. They are .0001" graduated. I got the Enco brand for about $30. At the time, the Mitutoyo's were going for $300ish for the same set. My mics have stayed dead accurate over the years, and I'd put them up against anything out there...within the realm that I use them, that is. If they had constant, heavy use, I'd prefer the Mit's.
It's always good to find a supplier for the odds-n-ends that are hard to find, or expensive. From what I looked at on Victor, they beat the crap out of Mcmaster on some of the products. I'm willing to lose a few quality points on a tool that will not be used often...or will get so heavily abused that I'd feel bad about buying the high quality version.

[george wilson]

McMaster is always popular,but I think they are expensive.