Hardened tool steel question... for the experts

[Rick Markham]

Ok, I've got a question for the tool makers/ metallurgist fellers here... I don't want to beat the O1 vs. A2 tool steel drum again... Just looking for some expert advice. If I buy hardened O1 precision ground flat stock (rockwell 62-64) is there anyway of cutting the stock to length without having to temper and then re-harden the stock? I am assuming that it is too hard to cut with a hacksaw and the teeth will just disappear from the blade, can it be ground with an angle grinder (assuming I can prevent bluing the steel in the process) or am I risking a cutting disc spontaneously disintegrating with associated "excitement" involved. I only ask, as I respect your experiences/ ideas and have found very little information on the net.

I'm in the early stages of setting up a woodworking "tool making" hobby for my own amusement/ education. I appreciate any advice y'all can provide

[george wilson]

The precision ground tool steel you can buy is not yet hardened. It can be easily sawn,filed,ground,etc. Just do be careful to not let it get a little hot when sawing. It can suddenly surface harden a few thou. deep,and take the teeth off your saw. I've even had that happen from filing too vigorously.

01 is the simplest metal to use. You heat it up orange,and no hotter!,quench it in vegetable oil,transmission fluid,or any thinnish oil(DO NOT use USED motor oil! It will deposit a THICK coating of black from the carbon. It's hard to remove). The coating itself is REAL HARD.

To temper,polish the discoloration of hardening off at least 1 side of the metal with wet or dry paper. For a plane blade,heat it SLOWLY near the top end of the blade.Let the colors creep towards the cutting end. A medium brown color will be good. I always found that a plane iron that would BARELY file with a new,fine cut file,would hold the edge the best. If the iron stays too hard,the edge will break off microscopically and it will seem to be dull.

For a knife,the same color is o.k.. Heat the blade to a spring blue for a spring.

Learn to brush the flame over the metal carefully when tempering,and apply heat slowly,or it will suddenly go blue on you when you didn't want it to. Then,you must re harden,and re temper.

Do NOT try to harden a plane iron with the bevel already on it. It will surely warp. This is because of the different amount of surface area on either side of the blade.

If you drill holes,especially near the edges,stomp them tightly with fine steel wool,or a crack can happen when you quench the tool. Use a flat nose punch to hammer the steel wool in.

If you always use the same steel,you will get to where you can learn to get the most from it. That's how I started.

[Leigh Betsch]

Cutting tool steel at 62/64Rc is going to be pretty difficult. You could use a die grinder with a cut off wheel, or mount a 6" cut off wheel in a pedestal grinder. In either case you will have to be careful not to pinch the cut off wheel or it will shatter, wear a face shield. You pretty much have to use grinders with coolant to keep from heating hardened tools steel and loosing the hardness. Unless you have a wire EDM in your garage!
I've heard of some people doing a localized annealing of hardened steel so it can be machined although I've never tried it myself, maybe someone else has some experience.
It's not common to get hardened ground flat stock, it is usually sold in the annealed condition so it can be machined and hardened afterward. Are you sure you are buying hardened stock?

[harry strasil]

I cut old laid on plane blades to make narrow blades for my woody plow plane with a plasma and it worked well, very shallow and narrow heat affected zone.

[Rick Markham]

Ok, from the look of the website, (don't want to post a link here) It looks like it sold in the annealed state. I must not have read carefully enough the first dozen times :o. That makes me feel better about workability.

Now I guess another question is in order. I am looking at making a 3/8" thick by 2" wide blade (no holes drilled) and of a reasonable length 6" or less. This is probably the largest iron I would be making. How would y'all set up a "reasonable" way to temper the iron as evenly as possible? Would it be advantageous to set up a small "kiln" instead of just using an open flame on the blade? One of my childhood friend's father was a potter and had a large kiln that he closed off using ceramic (I'm guessing) bricks to trap the heat in the business end of the kiln. (I remember him pulling one out to show us once, cool enough to handle with a glove on our side, glowing white hot on the inside)

This isn't something I am planning on making just a few tools and abandoning, this is something I plan to pursue for quite awhile.

George, I am glad you chimed in your experience in these regards is priceless. I was planning on sticking to O1 tool steel for consistency sake, since I'm learning all of this, changing as few variables as possible seems like the smartest idea.

[Rick Markham]

I cut old laid on plane blades to make narrow blades for my woody plow plane with a plasma and it worked well, very shallow and narrow heat affected zone.

Harry now that is also something that I had been thinking about too. I'm kind of glad you mentioned it. I have no experience with plasma cutters, but had considered that idea as well

[harry strasil]

The kitchen stove oven is what most knife makers use, at from 350 to 400 degrees. Its a very even and constant heat.

[harry strasil]

on thicker material you have to be careful as the kerf will be tapered on one side and undercut on the other, been awhile, but I believe the undercut is on the right side in the direction of travel, a plasma cutters heat is approx 28,000 degrees and the plasma comes out of the little nozzle at approx 212 mph. wear a mask the plasma puts vaporized metal into the air.

[harry strasil]

other options for blades that need some sort of special shape are wire EDM (electro discharge machining), laser cutting and water cutting. the last two leave virtually no slag to clean up.

[Rick Markham]

on thicker material you have to be careful as the kerf will be tapered on one side and undercut on the other, been awhile, but I believe the undercut is on the right side in the direction of travel, a plasma cutters heat is approx 28,000 degrees and the plasma comes out of the little nozzle at approx 212 mph. wear a mask the plasma puts vaporized metal into the air.

Yeah, I know from being in a chemistry lab with a Plasma Spectrometer, that essentially the plasma is at a temperature that it frees what ever it comes in contact with into individual atoms. Which is why I thought it would be an interesting way to cut it, I've noticed they are on craigslist here fairly regularly. I'm not terribly concerned about the cleanliness of the cut, I am planning on wet grinding to clean up the surfaces, at least until I can get a milling machine. I'm not afraid of some sweat and elbow grease either ;)

[Robert Rozaieski]

Tempering is easy to do in the kitchen oven as Jr. mentioned. Just set the oven for 375 to 400 degrees and pop the iron in for 45 minutes to an hour.

However, tempering is the second step of the heat treating process. Before you temper, the first step is to harden the steel. This consists of heating the steel to orange as George mentioned, and quenching in oil. With a plane blade 3/8" thick by 2" wide, I don't think you can harden that at home. It will be very, very, very difficult to get an even heat through such a thick piece of steel with the torches you likely have, if you can even get such a thick piece of steel to orange heat with the torches you have at all. You will need a furnace to heat steel that thick.

Why 3/8" thick anyway? That seems awful thick to me for any woodworking iron. Even the old thick vintage tapered laminated irons usually weren't over 1/4" thick at their thickest, and these were not solid tool steel. I think 3/8" thick is going to be overkill, and any money you save by making your own iron will be lost when you have to send it out to be heat treated. I'd consider using a thinner steel, like 3/16" to 1/4" max. Even these will be a challenge to harden with a home setup. You will need a high output wide flame torch and a few fire bricks like Larry Williams has recommended in the past in order to get an even heat on such a wide blade. Standard plumbing torches with a pencil point flame won't cut it for big wide plane blades. For molding plane blades (which are typically narrow and no more than 1/8" thick) plumbing torches can be made to work, but for wide, thick bench plane irons, you need more firepower (pun intended) :D.

[David Weaver]

Propane weed torch (not the largest one) and some refractory bricks ($50 plus the bricks, they're available cheap here from time to time in former steel land, but at the worst, I think they're about $8 per for lightweight ones from mcmaster carr - the light weight ones are nicer to work with).

It's so much easier to work with unhardened metal that I would stick to that and then harden it yourself.

I also agree with Bob, 1/4" is plenty thick and chatter issues that you'd have with thinner blades don't exist with it. You'll appreciate that it's not thicker than that when you put it to the grinder (or belt sander especially), and if you're building a plane, 1/4" irons give you plenty of room to work around the mouth roughing it out and then still have it tight when you finish it to size - without having to safety grind the backside of the files.

[Rick Markham]

Thanks David, I appreciate it. Thats a good piece of the puzzle right there.

[Bob Haverstock]

other options for blades that need some sort of special shape are wire EDM (electro discharge machining), laser cutting and water cutting. the last two leave virtually no slag to clean up.

Harry beat be to it with his answer.

If I didn't want to be invoved in the heat treating, I would purchase a 36 inch length of width and thickness needed. Then I would have the whole length heat treated by a commercial heattreater. A waterjet would be the cutter of choice, no heat affected zone. BTW, heat treating carbon steel isn't really hi-tech.

If I were not familiar with heat treating on a small scale (no pun intened) and wanted to learn the basics, I would google ABANA and go to the chapters in my state. I would find the closest local group and visit them, watch, ask questions, and learn. It is as simple as cutting dovetails.

Bob Haverstock

[george wilson]

Rick,there are many heat treating outfits out there. Look up some knife maker's sites and find some. Thing it,it might be a buck or 2 to harden 1 blade.

I use both a Whisper Daddy 3 burner gas furnace,or for more serious control,a 22" deep knife maker's electric furnace with a pyrometer to accurately control heat.

For tempering,a kitchen oven actually only is something like 75º accurate. Probably best to use tempering colors. I actually have used a toaster oven,BUT BUT BUT,with an accurate high temp thermometer from Brownell's Gunsmithing,with a 9" probe on it inserted into the oven. This was actually recommended in an excellent book on heat treating. I can't recall the exact title. Had to leave it when I retired. It is a smallish blue book in paperback. Other that "Tool Steel Simplified" by Carpenter Steel Co.,now out of print,it is the best book out there. In fact,it offers better tips and insights than any other book. The Carpenter book is much larger,but I recommend the smaller blue book.

P.S.,I googled it,and CANNOT FIND the book I refer to,and there are a lot of blue colored books out there. I'll have to get back to you. I have pneumonia right not,and can't recall a lot.

In reality,there is only about a 25º range in hardening to get the best results,but you aren't making a $250,000.00 die.

Be careful to not get above an orange color(called "cherry red" by many),though I think cherries are dark red,except in the Spring.:)

If you burn the metal,it will have little blisters all over it,and is ruined.

I'm assuming you don't have advanced means to cut your metal out. I didn't either years ago. You can just hacksaw it out. Put some oil on the blade and it will be easier.

I really don't see the need for a 3/8" thick blade. 1/4" is as thick as I ever made them,and will never flex,believe me. The plane itself is MUCH weaker than any 1/4" blade. You are just setting yourself up for much more work and expense. The throat will be huge,unless it is bevel up.

A pottery kiln would be o.k. IF you can control the temperature,and access the metal easily. They aren't made for that kind of work. Many have the lid on top,and you DO NOT WANT to try to get into an open lid at hardening heat. It's enough trouble with a front opening furnace and long tongs,believe me. Your flesh can be vaporized at that heat.

There are many knife makers who send their blades out for hardening. It could be $30.00 or more,though. I don't really know,since I've hardened my own.

The gas weed burner probably would be o.k.(I never used one),but you need to build a brick hearth. Use fire bricks if possible. ANY moisture in the bricks will make them blow up,showering everything with very hot fragments. Keep it indoors.

What I do when just using a torch,is make a corner out of the bricks to help trap the heat. It helps a lot. Sometimes I use 2 Mapp gas torches. I have been able to harden 3 inches or so of 1/8" X 2" 01 steel this way. Beyond that,before I had a furnace,I went to the historic area and used a forge.

[Rick Markham]

George, thanks for the info. That gives me quite a lot to work with as far as research goes. Having someone do the hardening for me, might be the best route.

I value my flesh, so there will be no top loading ceramic kilns here. The firebrick hearth seems like an attractive idea, and I am going to look into that definitely. It will definitely be kept inside, exploding 1500degree+ bricks sound like too much excitement to me.

As far as the forges, and the heat treating ovens. They are a bit out of my price range at the moment, but I am not against saving up for the right tools for the job.

If I do decide to make my own plane irons I won't be making anything over a 1/4", I definitely trust everyones advice in regards to that. As far as using thicker material I do have a desire to make some mortise chisels eventually, which would require thicker stock.

I'm trying to set myself up in as flexible way as possible. Since I am not going to go run out and buy all of this stuff on a whim (being a long term project) its important that I do it the right way the first time.

[george wilson]

I had a friend who used to make a forge out of an old steel automobile wheel. He used the exhaust from a vacuum cleaner for air.

I can warn you that you MUST limit the amount of air coming into the forge, or it will cool the fire down rather than making it hotter. I learned than many years ago when I made a melting furnace. I had to block off about 90% of the air intake on the blower to melt brass.

You can buy refractory clay to line the wheel with,so it doesn't melt the wheel. Call 1-757-229-1000 and ask for George Suiter at the Geddy Foundry for the correct clay to buy. They use it to repair their forge. Tell him I sent you.

[Rick Markham]

Thanks George, I greatly appreciate it! That sounds like a pretty interesting idea, I can imagine it takes a little tinkering to get a feel for all of it, it's good that happens to be something I enjoy.

[george wilson]

You'd have to erect an airtight brick box mortared shut under the steel wheel. Leave a hole to stick the air hose in. It would be better if you had a squirrel cage fan that you could lay a piece of cardboard over the air intake,to let only a fairly gentle wind blow into the box,and up through the forge.

You need to make coke,which is easily done. just get the fire started,pile up a pile of coal and let it all catch fire thoroughly.Then,pour water on it to put it out. A big smelly cloud of sulfur laden gas will come off the coal,which is what you want.The lumps of porous,grayish looking material you will have left is coke. It is just coal without the sulfur,and is nearly pure carbon. You can build a wood fire under it,and re light it. The object is to make a pure,sulfur free fire,as sulfur is very bad for steel,especially for welding it.

You could just use charcoal briquettes for grilling food if getting coal is a problem. For heating up a plane iron,it won't cost much,and you won't have to "coke" the charcoal,as it's pure carbon already.

In a forge,you need to get a hill of the fuel started,and jam the end of the iron into it. This also helps keep oxygen away from your metal,so it doesn't lose surface carbon. That isn't really a problem at the hardening temp. required by 01 steel,though. As long as you don't get the 01 too hot,it won't lose carbon. You need to be VERY CAREFUL,because it is easy for the iron to get white hot,or even start sparkling,which is welding heat. Anything over an orange color is too hot.

[Sandy Stanford]

George, thanks for the info. That gives me quite a lot to work with as far as research goes. Having someone do the hardening for me, might be the best route.

I value my flesh, so there will be no top loading ceramic kilns here. The firebrick hearth seems like an attractive idea, and I am going to look into that definitely. It will definitely be kept inside, exploding 1500degree+ bricks sound like too much excitement to me.

As far as the forges, and the heat treating ovens. They are a bit out of my price range at the moment, but I am not against saving up for the right tools for the job.

If I do decide to make my own plane irons I won't be making anything over a 1/4", I definitely trust everyones advice in regards to that. As far as using thicker material I do have a desire to make some mortise chisels eventually, which would require thicker stock.

I'm trying to set myself up in as flexible way as possible. Since I am not going to go run out and buy all of this stuff on a whim (being a long term project) its important that I do it the right way the first time.

Rick, there are plans floating around on the 'net for brake drum forges.

http://www.youtube.com/watch?v=kuMkIJGri2M

[george wilson]

Hadn't heard of brake drum forges. Only wheel forges. The guy with the shop vac is letting WAY,WAY,WAY too much air into the fire. That will make it burn faster,but will also keep the fire from getting as hot as it can get. You could cut a long hole in the hose,and make a cardboard tube to slide over it to put just a GENTLE breeze into the fire. By giving my forge just a VERY small amount of air,I was able to even melt some cast iron,but with too much air,I couldn't even melt brass. So,be careful of the air.

The steel 5 gallon drum is a good idea. It won't get hot enough to be harmed. You could paint the drum inside and out with 1400º engine enamel to keep it from rusting away like crazy from the heat. Just paint the upper part,will be fine. You'll probably paint your arm trying to spray the whole inside!!

[Rick Markham]

Now that's pretty interesting! I've got a couple ideas, I am tossing around in my head, I will let ya know how that works out :D I hope your feeling better George!

[Andrew Gibson]

Rick, I will volunteer to be a guinea pig for some mortise chisels... I don't have any and could use a couple. :p:D:cool:

My dad tells a story about him and his brothers building a forge for his dad to melt aluminum in. I dont remember how they did it but i know they used an old vacuum cleaner to stoke the fire.

[Rick Markham]

Rick, I will volunteer to be a guinea pig for some mortise chisels... I don't have any and could use a couple. :p:D:cool:

My dad tells a story about him and his brothers building a forge for his dad to melt aluminum in. I dont remember how they did it but i know they used an old vacuum cleaner to stoke the fire.

I think that probably can be easily arranged Andrew. I hope things have been going well with ya, it's been awhile... ya keeping yourself busy?

[Andrew Gibson]

I think that probably can be easily arranged Andrew. I hope things have been going well with ya, it's been awhile... ya keeping yourself busy?

I've been doing good, Getting over a back injury and trying to get a few more projects lined up. Also getting ready to give grad school a try.
all in all I can't complain.

[Rick Markham]

Glad to hear it Andrew! I'm busy with school too, so I can relate!

George, I thought I would give you a little update. I managed to win a small electric knife makers kiln on "the bay" with an electric pyrometer:D. So that should take care of that aspect of it. Now I just need to get some required accesories. What style of blacksmith tongs do you recommend? I've looked at a few online. I am also planning on investing in a good set of heat resistant gloves that are rated up to 1700 degrees. I guess I need to make a order for the tool steel now. Any advice that you can give me regarding using the kiln, is always appreciated. ;) Do you know the temperature for the color you are referring to on O1 tool steel? Do I temper it after quenching? (I'm planning on quenching in peanut oil) Thanks again for all of your help!

[David Weaver]

If you get starrett steel from mcmaster carr (which is about the same price as ground O-1 anywhere else), it'll tell you the temperature on the label, as well as a schedule of tempering temps for different final hardness - I think the label says 1450F for the hardening.

[george wilson]

Make sure that the pyrometer actually will HOLD the kiln at a certain temperature,rather than simply telling you what the present temp. is,while it keeps climbing. My first kiln was like that. I had to sit there and turn the kiln on and off to keep it at the temperature I wanted it to stay at,or it would drift on up to about 2000º.

Invest in a tool steel book to get your temperatures for different steels. 01 is hardened at 1450-1500º. You should stuff all holes drilled in it with fine steel wool, STOMPED in with a flat nosed punch and hammer. This keeps cracks from developing when you quench it.

The quench must be large to not get warmed by the tool being quenched,or it may not harden. Often the quench will catch fire right around where the tool is thrust in. No big deal(it goes right out),but could mess up your wall with soot over time,so be prepared. Quench your parts vertically,and get them completely under the oil to put the fire out. I don't know if peanut oil will burn,but many oils will,automatic transmission fluid will!

Make certain your gloves STAY DRY,or they will generate scalding steam before you can get them off.

Peanut oil is fine. I hope it doesn't go rancid. We used a 5 gallon bucket of automatic transmission fluid,and another of brine. To make brine,dissolve ICE CREAM salt in water until a potato will float in it. I used distilled water,as the local water may have minerals in it that affect the quench. I don't know why ice cream salt is best. Maybe Harry Strasil can chime in.

Brine is better than water,as it keeps a GAS ENVELOPE from forming around the metal. Water will let the gas form. It keeps the steel from hardening evenly.

[Rick Markham]

David, Thanks. I will definitely start there.

George, I am not entirely sure whether it is a controller or not, I am expecting to babysit it if I have to, I also noticed that there are some aftermarket controllers available and that is a definite option if It isn't a controller. I got a good enough deal on the thing that it is definitely in the budget. Do you have any recommendations on books... I'm not afraid of reading and learning:)

Oh yes... I learned the dry gloves thing in professional kitchens! I can only imagine how much worse it would be at 1400+ degrees!

[george wilson]

You can actually Google information so much that it might be the way to go,if you are making things out of 01. Fill any holes like I said,and try to avoid sharp inside corners in the work. They can crack,too,though with 01 I haven't personally had corners crack. Holes certainly can crack,though.

If you make a long,thin item it will likely warp. Polish off the surface,and heat to a light straw color. WHILE IT IS HOT,you can bend it like a noodle to straighten it. When it gets cold,it will snap like glass. I've straightened reamers like that. File makers straightened files that way. Take a block of hard wood,and saw a thick,strong fork in it. Clamp the block in a vise. Straighten the item by twisting it between the forks. It'll burn the wood,but just replace the fork when burned out.

[harry strasil]

I don't know about the ice cream salt other than it may dissolve more quickly, usually brine is a 10% salt solution, brine makes small bubbles that scrub any scale off the piece. normal quench temperature is non magnetic, 1460 degrees, which is the tranformation point for most steels, to determine non magnetic suspend a good magnet from a thin copper wire on a long handle and when the magnet does not attract to the hot steel its the right temp. and don't move the piece around in the quench medium as this will cool one side more than the other and result in warping. FWIW, if the piece forms scale its too hot as most steel forms scale at 1550 degrees

[Ron Hock]

Hi Rick,

I've posted some DIY heat treating instructions here (http://www.hocktools.com/diyht.htm) and there is a lot of info about tool steel metallurgy, including heat treatment, in my book, The Perfect Edge (http://www.perfectedgebook.com).

O1 is a great steel both for the edge you can get with it and for its relative ease wrt how it machines and how it hardens. Large blades require a large heat source, such as an oven or furnace, and an accurate way to ascertain the temperature. The target temperature for hardening is 1450 to 1500F. To low and it won't harden fully, too high and it will grow large grains which weaken the final product. The visual color change at the right temperature is a good indicator but it takes a few tries to learn it well enough to trust your judgment. A magnet is a sure thing as a temperature gauge (for O1 anyway) but it means poking around in bright orange heat. Peanut oil is a good quench because of its high flash point, but it can still catch fire so proceed with all due caution (and protective gear, fire extinguisher handy, etc.) Heat treating is not for everyone but it's not rocket science and you can do it successfully yourself.

O1 is readily available (mscdirect.com and many others) and as inexpensive as tool steel gets. As to the thickness issue, I wrote about that recently in my blog (http://hocktools.wordpress.com/2010/06/14/of-thick-and-thin/). (Summary: thicker isn't always better.)

Good luck with the project. I assume we'll be reading about its progress and I will look forward to it. Be careful out there.

[john brenton]

Ron,

I read your book a few months ago and I found it informative and kind of informal in a personal humorous way. The pictures were great too. Just about every time I put a chisel on the grinder I think back to the picture of the chisels edge bluing up with the caption "Oh @#$!" It cracks me up.

I look forward to any other publication you would put out and will be checking out your blogs.

[Rick Markham]

Hi Rick,

I've posted some DIY heat treating instructions here (http://www.hocktools.com/diyht.htm) and there is a lot of info about tool steel metallurgy, including heat treatment, in my book, The Perfect Edge (http://www.perfectedgebook.com).

O1 is a great steel both for the edge you can get with it and for its relative ease wrt how it machines and how it hardens. Large blades require a large heat source, such as an oven or furnace, and an accurate way to ascertain the temperature. The target temperature for hardening is 1450 to 1500F. To low and it won't harden fully, too high and it will grow large grains which weaken the final product. The visual color change at the right temperature is a good indicator but it takes a few tries to learn it well enough to trust your judgment. A magnet is a sure thing as a temperature gauge (for O1 anyway) but it means poking around in bright orange heat. Peanut oil is a good quench because of its high flash point, but it can still catch fire so proceed with all due caution (and protective gear, fire extinguisher handy, etc.) Heat treating is not for everyone but it's not rocket science and you can do it successfully yourself.

O1 is readily available (mscdirect.com and many others) and as inexpensive as tool steel gets. As to the thickness issue, I wrote about that recently in my blog (http://hocktools.wordpress.com/2010/06/14/of-thick-and-thin/). (Summary: thicker isn't always better.)

Good luck with the project. I assume we'll be reading about its progress and I will look forward to it. Be careful out there.

Thanks Ron, I appreciate it. I will definitely be investing in your book. I will let ya know how all of this turns out :)

[Sandy Stanford]

Thanks Ron, I appreciate it. I will definitely be investing in your book. I will let ya know how all of this turns out :)

To really control the process, you need to smelt your own ore.

[george wilson]

We did smelt bog iron twice in Williamsburg,and produced some wrought iron. It wasn't tool steel,though.:) I assume you were joking?

[Rick Markham]

believe it or not, I have a friend from school that made a crucible furnace to do lost wax castings from. Pretty ingenious actually. Smelting iron sounds like a very hot messy operation, I think the neighbors might object :p ...always a comedian somewhere... usually it is me :cool:

[David Weaver]

Anyone ever use kasenit when they're hardening O1?

I got a tub of it once ordering from mcmaster carr, at the suggestion of Jack (T...something, can't remember his handle on woodnet) a while ago and just did 2 moulding plane irons over the weekend and forgot to try it.

I probably go past the temp point that you're supposed to go to by definition, but thus far, my irons have held up fine - none of been in anything critical, though, just stuff like a bullnose planes, some chisels and moulding plane irons (which never seem to be that hard or durable in old planes, anyway).

[Rick Markham]

What does kasenit supposed to do during the hardening process?

[David Weaver]

What does kasenit supposed to do during the hardening process?

Introduce carbon - it's a surface hardener. I guess used more for applications where you want surface hardening only, but Jack (still can't remember his woodnet handle) swore by it, and claimed it has better penetration in some cases than just surface hardening.

I'm just wondering if it would be helpful in protecting those of us with torches against overheating, at least to a small extent - even though that's clearly not what the label suggests to do with it. The instructions on it say you'll get 5 thousandths of penetration at 1650 degrees for 15 minutes of heat, so it's not like you're going to accidentally put a thick skin of super-hard brittle steel on something - at least not if it works the way it says it does.

it's not expensive, but it's also not at every mom and pop hardware store - just something to experiment if already making an order somewhere that has it.

[george wilson]

Kasenit adds carbon to low carbon steel. It should not be used with 01 as 01 already has a lot of carbon in it. Most likely would make the 01's surface too brittle.

David,unless your steel got blisters on the surface,you didn't overheat it. We had a half baked black smith in our maintenance area who knew nothing about heating steel. He blistered a knife some other guy had made from L6 steel. It came from a large bandsaw mill blade about 6" wide,and about 3/32" thick. The knife had blisters all over it,and it snapped in half like a piece of melba toast!!! In the first place,the steel was already hardened and tempered,and did not need hardening anyway.

David,just read your last post. What you need to protect steel from the flame,is PBC No Scale,from Brownell's Gunsmithing Supplies. Heat your steel up to any color at all,and dip the part in it,or sprinkle the part with PBC. It will come off with boiling water after you quench the steel in oil(just flies off if you quench water hardening steel in water),and it will leave the surface nice and clean.

In the 18th. and 19th.C.,they used BEER LEAVINGS in England to protect Stubbs file teeth while hardening. I have used an old recipe of just flour and water,with some yeast,and a bit of salt. I think the yeast helps glue the flour together. Coat the steel liberally with this mixture. It does work,but smells like burning bread. It turns into a thick coating of carbon,and does do a decent job of protecting the surface,though PBC does a bit better.

Actually,Kasenit will not case harden as deep as plain charcoal packed around the steel in a luted crucible.

[David Weaver]

Not blisters, but some black scale. At the first sign of blisters/migration, I put the irons in the oil. The last iron, they never really occurred - I may have been getting too ambitious about how much cutting length I was applying heat to. Since I was only doing narrow irons (a little greater than 5/8ths) and they're only for moulding planes, I was using only one mapp torch this past weekend.

I guess I'll take the irons back out of the planes and make sure a file doesn't file them. They're not going to see hard duty, and I tested the planes after honing them to make sure I could say I was otherwise done with them. They held up fine, and I used diamonds to lap the backs flat after hardening, which sort of handicaps the ability to be able to tell how hard the iron is.

Thanks for the advice on the PBC. I guess I'll stow the kasenit. Rubber hasn't hit the road yet, because I've only been making oddball stuff, like moulding plane irons and an iron for an old slater bullnose, and hardening blunted chisels as scrapers for bedding irons (something I learned off of a bill carter cd). If they're not that durable, it doesn't matter.

I don't have the sense that I can tell enough of what's going on to make a good durable smoothing iron that won't have me thinking I should've just spent $35 to get a new commercial one.

[Sandy Stanford]

We did smelt bog iron twice in Williamsburg,and produced some wrought iron. It wasn't tool steel,though.:) I assume you were joking?

Yep, just joking.

[Rick Markham]

Yep, just joking.

Dang, and I just ordered a steam shovel and giant dump truck... :D

[george wilson]

Oil makes the black scale from being burned.

[dan sherman]

Rick,

If you get really serious, you can look into getting a small electric heat treat oven. Depending on features you could get one that will do everything you need it to for $900 - 1500 New.

[Rick Markham]

Well it's a start... It's a small Sugar Creek "Good Kiln" I have an order coming of some O1 tool steel for some experimenting. It has an electronic pyrometer and infinite switch... next month I will invest in a controller for it after some preliminary tinkering. Got a good deal on it so I am pleased. Got some gloves rated at 1700* F, a heat resistant sleeve, and a pair of blacksmith tongs coming too... pretty excited :D
http://img.photobucket.com/albums/v295/Rick357/006-2.jpg

http://img.photobucket.com/albums/v295/Rick357/007-2.jpg

[Leigh Betsch]

Sweet! How hot will it go? A long time ago we used to cook pizza on the night shift in the heat treat oven. We had to leave the door open or it would burn. Probably got some kinda metal poisoning that explains my personality today!

[Rick Markham]

LOL, that's pretty funny Leigh. It goes to 2000*F According to the paperwork. We will see, I'm going to build a small removable stand out of black iron pipe so I can put it out in my car port when I use it and bring it inside when it is cool to store it, Gotta make a run to the Borg for that tomorrow or the next day. I will try firing it up then... Mine is only big enough for Personal Pan Pizza's ;)

[Leigh Betsch]

What is the chamber size? I could use one of these units! But first on the list of stuff I don't need but want more than stuff I do need is a surface grinder. I'm getting darn sick of hand lapping these blades flat....

[Rick Markham]

9" wide, 10 3/4" deep and 4 1/2" high. Not huge but big enough for my uses. They also make a 220V one that is 22 or 24" deep. But there wasn't one of those on sale on fleabay

[dan sherman]

Rick,

I don't see any kind of keypad to program it, is it just an on/off unit? Can you control the heat up and cool down rate?

[Rick Markham]

Dan, at this point it is purely manual with an infinite switch. They have an add on programmable controller with all those features, I will be investing in that soon. Until then I will be babysitting it, I should be able to get the controller soon enough that I shouldn't have to babysit for too long.

[george wilson]

That is quite similar to mine.

If you can also get a toaster oven,and a high temp. thermometer with a long probe on the back from Brownell's gunsmithing,you will be well equipped. The toaster oven can probably be found at a second hand store. Do not trust its thermostat,though. Insert the thermometer.

[Rick Markham]

Is that what you use for tempering George?

[george wilson]

Yes. The only way you can temper the hardened tools when they just get cool enough to barely hold them ,about 130º,is to have a hot oven ready to put them into. Since you only need about 400º,a toaster oven works fine IF you have accurate control of the heat.

[Rick Markham]

Ok gotcha George, I have an electronic thermometer with a probe, that I used to use for sugar work, think that will work? (It has to be extremely accurate for sugar, + or - 5degrees is major changes in the stages of sugar)

I've heard various lengths of time for tempering, how long do you leave your 01 tool steel in for?

[Andrew Gibson]

All this talk of Pizza and toaster ovens is making me hungry.

Not to mention I just looked at the nice table over in the project forum made with roasted birch.

Who said men should stay out of the kitchen? We just make our own out in the yard :)

[Rick Markham]

That's funny Andrew! My "old lady" is always trying to get me into the kitchen... I guess a professional chef never really retires! I do love cooking out on the grill though :D When I think of "roasted birch" I think it needs to go into my smoker under a couple slabs of spare ribs ;)