I've been bladesmithing for about 15 years now, and have been wanting to try a sword.  I've actually got a sort of Falchion forged and rough ground, but while I can harden it, I'm having trouble wrapping my head around tempering it.  Trouble is, my oven is only 24" deep, blade and tang is a bit longer than that.  

I've thought about heating a bar of steel in the gas forge and running the back of the blade over the sword and watching the temper colors, or even putting a steel pipe in the forge as an oven.  I've seen a pipe with oil heated and used for tempering on Man at arms, reforged, but not sure how high a temp the oil can stand, or what oil to use.

How do you sword makers do your heat treat?

Thanks

try the BBQ grill with a remote cable type probe, temperature cooking type, increase or decrease coals as needed, yes you can use the briquettes for this one, throw on a steak too, close the lid and turn the blade often

How are you hardening? 

If your BBQ isn't big enough look around for a pottery / glass kiln. The new ones have digital controls, and programming capabilities.

I will be hardening in the gas forge, it's 15" long and by working the blade back and forth I can get it to critical temp, have done so while normalizing it, then quench in a tube of oil.

I have a Paragon heat treat oven, but the internal capacity is only 24 inches.  If I was to get set up for doing swords I'd either get a larger Paragon or Even Heat for sword length blades or go with salt pots.

My grill is a Big Green Egg, it's only about 22" or so across the middle.  I might do the briquet style tempering with a trench in the ground and a large pipe over it, would have to watch the temperature, but it might be doable.

Geeze folks...is this too obvious?? Ok you have a gas furnace/forge..you know the excess flames that come out the front/back? Temper the blade in that..just move it back and forth until you get the colour you want..oil quench..clean off the oil when  at ambient, brighten the surface.. and use a red hot piece of iron/steel bar to draw back the areas you want softer by placing the bar on the area..watch the colour..they can come up quick..

This is very simple but it tales some practice..I suggest you try this on a piece of scrap the same basic size as your blade to get the feel of it..  doesn't take long....

 

JPH

Thanks, I'd been thinking along those lines, and that's what I'll probably do, part of it is wrapping my head around the higher temp, shorter duration tempering.  Normally on knives I do 3 two hour temper cycles, I've found I can lower the tempering temp and still maintain toughness.  I also have a torch, so that's easy enough to bring the tang to a higher temp.

One other possibility I've though of, but haven't tried yet is tempering tongs, basically tongs with a couple large chunks of steel that you heat red hot and clamp on the back of the blade to do a differential temper.  Wouldn't work with a double edged blade, but might work for a single edged blade, just take a while to get the whole blade done and for 2-3 cycles.

That's about all I can think of short of getting a larger oven, and don't want to get into that expense this early, might make more, might not, we'll see.

Hello:

Using "tempering tongs" on a double edged blade most certainly works..I do it all the time..just depends upon the tong jaw design that's all...then again..what do I know about how you (or anyone else) work??  What facilities you have..tooling..level of skill and SLTT???...  so...all I can do is give suggestions as to what works for me..I've been at this a couple of years now and I did manage to figure out a thing or two in that time...

JPH

SLTT?  

I guess I could machine a set of jaws to fit, and leave the edges clear enough to avoid overheating them, didn't think it'd work good on a double edged blade.  Maybe if it had a fuller, just use matching radius jaws to fit the fuller and run the colors from there?

Reason I'm asking on here is it's such a different undertaking than my normal work.  I haven't tempered anything by color, other than a hammer or punch, in close to 15 years.  I like the performance and consistency I get out of an oven, and you've got to admit a sword has to be able to take more abuse than a knife.  I even put axes or hawks in the oven.

Basically for tooling I've got a coal forge, horizontal and vertical gas forge, 24" deep Paragon heat treat oven, and a toaster oven.  I've also got oxy/propane cutting torch, power hammer, hydraulic press, treadle hammer, a bunch of hammers and tongs and such and a couple of belt grinders, and a bunch of quality files.  I have a Smithy 3 in 1, but I wouldn't exactly call it heavy duty or precision, drill presses, a buffer, an arc welder, surface grinder, hand grinders, ect, in other words a pretty well outfitted home shop.  Probably the most used tool is the files and sand paper.

What I'm trying to figure out is the more common ways people who actually make swords use to temper there blades, and maybe give me idea's I haven't thought of or thought wouldn't work well.

Thanks

Hello!!

SLTT: Stuff Like That There,

OK I am not in in anyway as sophisticated  in  your set up as you have described here.. I am just a guy that has made a couple of swords over\ the years so..;. OK I will admit  that i have three to five years plus or so in forging swords and all...HOWEVER!! I am little more than a guy that started doing all of this in my neighbors place  and all that  but  In have been doing this for a few years ( at least 7 or so..plus a bit,...) or so who knows so.. Now I don't all that much as far as "Fancy/Schamcy heat treating goes..I am just a "HammerHead sorta guy but I do know that if you are careful...

JPH

 

No worries, and thanks for the input, I'll listen to anybody that's got more experience than me(with swords that covers just about everybody), and am open to just about any ideas.  I'm most likely overthinking things as swords have been made and heat treated long before electric ovens came about.

Not sure how well it'd work, but I'm leaning toward a long, heavy walled pipe in the gas forge, heat it to temp and shut the gas off, leave the hardened blade in the pipe and watch the temp so it doesn't over heat.  I'm thinking I may need to grind a piece of mild steel to test before screwing with a sword.  Or maybe just a hunk of steel plate on the coal forge and run the blade over it watching the colors and do that several times.

 

 

You going to pull the other one?   Dr James P Hrisoulas wrote the books on this stuff:  "The Complete Bladesmith", "The Master Bladesmith", "The Pattern Welded Blade"  His suggestions should be considered with all due consideration....

the JPH dude has short changed his years experience estimate by at least 40 years....

Well it's always nicer when other folk extoll one's virtues rather than having to blow your own horn...now about that last book we've been waiting on....

I temper swords in mar quenching oil, which is happily temperature stable for the temps I use (around 250C normally for swords), I have a very basic set up , an insulated pipe with a section of the bottom exposed where I put a propane torch, and a thermocouple and cheap reader in the oil. I generally pre heat with heated bars as otherwise its about 2 hours to get to temp. Its a constant loss system so you just adjust your burner to change temp. it happily sits pretty much where you want it to be temp wise, the oil circulates with convection currents so keeps the temp quite even.

 The only thing I would say is that you need to be careful of getting water in the oil, heating oil that has water under it can be messy and dangerous. I gently heat the oil through the 100C mark incase there may be some water at the bottom of the tank, a moisture drain tap at the very bottom is a good idea as well.

 There is about as much effort in low temp salts which is where I will go next (i have the salts) but the oil so far has been good on 100+ sword blades . I prefer it over an electric oven (which I also have) as there is a lot more thermal mass in the oil and this speeds up reheating the blade if it needs straightening at temper temp.

Sounds good, do you happen to have a manufacture ID of the oil?  All I've got on hand is Texaco type A, and Brownell's tough quench.

What your describing sounds like it wouldn't be too much trouble for me to build for a one off, or for occasional use.  May try a few knives from 1084 or 1095 with this for tempering.  I remember reading about Frank Richtig supposedly mar quenching 1095 to get the performance he did, or at least that's what they figured he did after micro graph's of some of his blades, Frank never did say.

How many temper cycles do you normally do and for what duration?  If I'm understanding you correctly, you are mar quenching your blades, coming straight from the forge to the pre heated oil and quenching.

Thanks

Hi , I am not mar quenching the blades but am using heated marquenching oil to temper as it has a high temp stability, I think peanut oil would be a good alternative. I quench into fast oil (Uk available exelquench fast oil) at around 40C. and then temper for 2 x 1 hour , straightening at the end of the temper cycle when thew blade is hot . I will happily reheat to straighten as much as is necessary.

Low temp salt pot.....best way to go in my opinion.

For one/two swords I suggest either going to someone who has the tools to do the job or make blades that fit in your house oven.

Ric

2 hours ago, Richard Furrer said:

Low temp salt pot.....best way to go in my opinion.

For one/two swords I suggest either going to someone who has the tools to do the job or make blades that fit in your house oven.

Ric

that is good advice, you can get a surprisingly long blade in double diagonally.

Thanks Basher, good idea on the peanut oil, I seem to remember it's got a very high flash point.

Thanks for the help, I think I've got it worked out, maybe won't screw up too badly.

Will52100, JPH is sorta like E.F. Hutton...........when JPH talks, blade smiths listen.... 

He really does downplay his contributions to the blade community. When my friend from Italy ,who is a bladesmith, had just moved to the States and  found out that Jim lived in the same area as we do he got all excited, and said his friends in Italy wouldn't believe it. He has that kind of reach around the world. Look into any of the books he has written, and start reading.

Keep it simple. Tempering is just time and temp. 

Thanks, trust me, I'm listening to everybody here, way more experience at making big blades than me.

I agree tempering is simple, just figuring out how to get it done consistently with my tools and equipment.  Think I've got it worked out, now just need the time to get it done.

On April 11, 2016 at 2:16 PM, basher said:

 I have a very basic set up , an insulated pipe with a section of the bottom exposed where I put a propane torch, and a thermocouple and cheap reader in the oil.

I'm wondering how much heat input would be required for a similar pipe set-up with full insulation on the outside.  The reason I ask is I noticed one can get electric band heaters at fairly good prices--$ 23 USD for a 600 watt, 120 V x 3.5 ID.  2 would probably be plenty of heat. Wrap one around the lower end of the pipe under the insulation and the second about mid pipe and you might have excellent heat control of the system with little fuss.

They have larger wattages and diameters also but larger wattages are usually 240 V.  

Just a passing thought--no clue how much heat input you'd actually need to keep the heat-time reasonable.

Interesting idea, I was thinking of using an electric bucket heater, I use one in my normal quench tank and it works well enough that I have to shut it off to prevent overheating of the oil.  A band heater would be a lot neater as well.

Another thought is if it does work well, it'd be easy enough to rig up a PID controller to maintain a constant temp.  I built one for my lead pot for casting and it works extremely well and didn't cost a lot to build.

I dont know how many KW a small bullfinch burner is but I think 600 watt would be very slow .

 A PID with either electric or controlling a gas solenoid would also be good. my super simple version has worked so well I have not improved it.

some use bolt on block heaters to maintain temp on low temp salt pots. I'll be going that route this year in lieu of the gas burner. Much better for vertical units as the heat is even up the side with little chance for pressure buildup from a cap of unmelted salt.

The concept came to me from KC Lund of California.