Knifemaking and other cool hobbies...

[Boerseun]

Water-quenching is notorious for fatally screwing up blades because of the size of the bubbles water makes as it comes into contact with 1200C steel. It flashes into steam and barely touches the steel, but where it touches its by no means uniform. So the steel warps.

Oil is best for it does flash into flame and boils, but the bubble size is a lot smaller. I normally use a tall pipe filled with oil so that there's not a lot of surface area where the oil comes into contact with oxygen. Minimal flames. I suppose the ultimate would be to have a pipe filled with molten lead, and let the steel cool down from 1200C to about 600C in the lead, and then take it out just above the melting point of lead and then dip it in oil. IDEA!!!

Gonna go buy me some lead tomorrow!!! That should be pretty damn even?

[nkt]

You could always add detergent to the water, to increase the wetability of it. The problem with that (and water) is you are going to wind up with a harder blade than you really want. If the back of the blade is that hard, it will likely shatter if you hit it against another blade, or something hard like a rock.

 

Using lead would be bad for you, and you would have trouble with the lead wetting the steel - it just won't. I've tried getting lead solders to stick to steels, and they don't. They tend to boil instead.

[Turtle]

Sheesh - now you're talkin' big bucks...

 

I hope you find something in them book things, GAHD, 'cause I've tried an' tried, and all I can think of is that it's simply uneven heating in the kiln. If it turns out ot be impurities, I'll just have to whack it on the anvil some. But that's tedious. I'm just wondering - if it is impurities, how much impurity do you need to cause a warp? 'Cause the steel is pretty uniform? I'm using 12C27.

 

___My metallurigal skill is largely with non-ferous metals in relation to jewelry & small castings. If you have room in the kiln, you might try reorienting your blade & see if the location of the buckling changes or the buckling is absent. This may at least narrow down the cause. :rolleyes:

[Turtle]

___On further reflection, it occured to me a variation in thicknes may cause the uneven heating & so a buckle. If so, the location of this thickness variation likely occurs in the center of the buckle, one of the ends of the buckle, or a distance from either end of the buckle that is a multiple of half the entire width of the buckle.

___

[C1ay]

I recommend you visit the Knife Network. They even have a Heat Treating and Metallurgy forum. I suspect someone there will be familiar with your dilemna...

[Boerseun]

Thanks, Turtle & C1ay.

 

I've spoken to a couple 'o guys on the net, and most of them say "Yes, buckling is a *****", but can't seem to pinpoint the exact cause.

 

I've got my own pet theory, and that is uneven cooling.

 

Differing thickness will also do it, as Turtle pointed out, but the blades are planed to a pretty level thickness. Moving the knife around in the kiln won't do - my kiln is an upright in which the knife is suspended from a special hook, and the element is coiled around it. So the heating is pretty even. It's the cooling that's bothering me now...

 

And one out of, say, six or seven blades buckles, from the same sheet of steel. So I don't know wether it is impurities. C1ay - can't remember whether it was you or nkt mentioning salting to remove impurities - what's that all about?

[C1ay]

C1ay - can't remember whether it was you or nkt mentioning salting to remove impurities - what's that all about?

Gahd mentioned that from one of the books he's reading....

[nkt]

Salting only applies if you are actually casting the metal from a melt. You salt the melt to get some of the crud out of it.

 

Boersun, you didn't tell us what the buckling was like? Is it that the center remains in contact, and the ends curl up?

[Boerseun]

Hi there

 

The buckling is very subtle, actually. I probably made it sound a heck of a lot worse than it is. For instance, a Bowie knife I made recently warped with about 4mm. That's to say, if you put it flat on a level surface, the middle of the blade stands out about 4mm from the two tips thats lying flat on the surface. You can whack it out on an anvil, but the problem is that wherever you hit it, the metal becomes compressed and screws up your acid treatment when you try to get patterns out of it. It can be sorted out for knives, but with the sword I'm planning on making, the buckling will be much more pronounced.

[C1ay]

You can whack it out on an anvil, but the problem is that wherever you hit it, the metal becomes compressed and screws up your acid treatment when you try to get patterns out of it.

Have you tried using a softer hammer to whack it out with, brass or even rawhide?

[Boerseun]

Got it sorted out!

 

Turns out that if you do a hollow grind on one side of the blade, and flip it over to do the other side, the grinder belt has worn off some. So - in effect, the flip side is ground with a second-hand belt, needing more pressure on the steel, thereby generating more heat and causing more stress to build up in the steel. And then, when you chuck it in the kiln for heat-treating, the stress is relieved by causing the blade to buckle!

 

What I'm going to try in the sword is to take two new belts, and dedicate a belt to a side. Every time the blade is flipped over, I'll use the other belt so that the heat builds up roughly equally on both sides, minimising the uneven stressing.

 

Gonna build my kiln now!

[Chacmool]

Congratulations! What materials are you using to build the kiln?

[Turtle]

Salting only applies if you are actually casting the metal from a melt. You salt the melt to get some of the crud out of it.

___As I said my casting experience is with non-ferrous metals; the salt I used is borax, we call it a flux, & the crud we call slag.

___Great news Boerseun; any chance of you favoring us with a photo of one of your blades? The acid patterning you mention sounds intriguing. :rant:

[Boerseun]

I tried attaching a photo of my latest blade, a Bowie with a stainless guard and an African Ironwood handle - but for some silly reason I keep losing my connection when I try to upload the file.

I don't have a photo of a sword, though, seeing as it's still in the process of being made!

 

Shall try to upload a photo a little later when my connection's a bit faster.

 

I got me one of those little mobile 3G PCMCIA cards in my laptop, and it's just dropped from 3G to GPRS. Joy.

[Turtle]

I tried attaching a photo of my latest blade, a Bowie with a stainless guard and an African Ironwood handle - but for some silly reason I keep losing my connection when I try to upload the file.

Maybe the file is too big? I think the limit is 90KB or so for an attachment.

 

___On the hobby side, I have an old Whites metal detector I use for occasional treasure hunting. It's the simplest model with a single knob/switch, but if you don't mind picking up trash it works well enough. I have found plenty of coins, scredrivers, knives, & pliers, as well as foil, caps, pull tabs, nails, etc.. I have some idea to go out looking for meteorites in Central Washington some day. A boy & his metal detector. :doh: Oh... & his survival wagon. :doh:

[Turtle]

___Yo Boerseun; taking up the bluing of steel question here. You mentioned it is troublesome & I agree. I have an old tool of blued steel that has areas of wear & small rust spots. I bought a paste bluing compound & have now applied several coats, first brightening the metal with an abrasive nylon pad, & then cleaning it with alchol (70%) before applying the bluing. It looks nothing like the original good areas yet & it's splotchy as well. Any tips or ideas? Is this the same trouble you have? :confused:

[Boerseun]

You talking about the gun-blue paste? I don't use that, seeing as when you actually use the knife and maybe scratch it, the steel shines through the blueing.

 

I basically heat the sucker beyond the ideal annealing temp for a very short while and get my blueing from quenching it. This kinda screws up the blade if your timing is out, because it makes the blade brittle - and thus also useless apart from a display piece.

 

The fun part is that you can make designs and patterns by using hammers, etc. It gives the steel different patterns of density, which you only get to see after you've annealed it. But that also leads to a high rate of scrapped blades, seeing as you literally can't see what you've done untill it's too late!