Knifemaking and other cool hobbies...

[Boerseun]

I have just finished off a hunting knife, and decided my next project is going to be a sword. Now - I considered posting this in the physics forum - I heat-treat my blades at 1200C, for roughly 30 minutes, after shaping them. Sometimes the blade comes out buckled, and have to be hammered on an anvil. Obviously the risk for this happening with a sword is much greater, seeing as the blade is a lot longer. Now, my question: Can the buckling be caused by uneven heating of the blade? Won't it help if I put the blade in cold, and let it heat up gradually with the kiln? The kiln takes about an hour to get up to 1200C, so I could let it heat with the kiln, and then leave it for 30 minutes? Could impurities in the steel cause the buckling? I have to build a new kiln for the annealling on the sword in any case, seeing as my knife kiln is too small, but I want to get behind the process 100% before wasting bucks on a new kiln.

 

Any other cool hobbies out there? Share it!

[C1ay]

Any other cool hobbies out there? Share it!

Rockets :D

lefthttp://hypography.com/gallery/files/9/9/8/PPGroup2_thumb.jpg[/img]

[Boerseun]

Schweet! Solid fuel? Altitude achieved? Parachute system? Gimme some details!

[C1ay]

Schweet! Solid fuel? Altitude achieved? Parachute system? Gimme some details!

Yes, ammonium perchlorate and binders. Around 2300 meters on the last flight. We deploy a small drone chute at apogee that allows the rocket to fall fairly straight while slowing it enough for the main chute to deploy at 100-200 meters.

[Queso]

i used to love making/launching rockets. i still do, i just don't do it anymore. it's time for me to buy another kit.

 

when i was a kid i colleced hot wheels and i have hundreds of them still, unopened. i think i'll see what they're worth in about 50 years.

 

but now, i love to record music. and once it's recorded, i love to mix it. and once it's mixed, i love to tweak the hell out of it. and once that's done. i love to listen to it.

 

i also love to explore and make abstract art ;)

[C1ay]

i used to love making/launching rockets. i still do, i just don't do it anymore. it's time for me to buy another kit.

Try Smokin' Rockets for a nice kit. I particularly like his Mega-Nuk ;) It rocks on an M series motor.

[Queso]

M!!!! the biggest i've ever used is a D. ;) wowowwowow

[C1ay]

M!!!! the biggest i've ever used is a D. ;) wowowwowow

Well, A D motor is in the range of 10 - 20 newtons or about 2.2 to 4.4 pounds of thrust. An M motor runs from 5120.01 to 10240 newtons or about 1128 to 2256 pounds of thrust. You'll need to be Level 3 certified to fly it though.

[nkt]

Well, lockpicking is one of the big upcoming hobbies at the moment, and I'm pretty into it.

 

I'm very in to mechanical things, hacking stuff together (and apart) and popping a lock open, whether to look inside, or popping it open with two bits of wire and a lot of skill.

 

I've actually set up as a locksmith, as I like it so much.

[Boerseun]

Haha, nkt - I won't invite you to my house any time soon ;)

 

I reckon this is a pretty cool thread - we should see some weird and wonderful things coming out of here, I reckon. We're gonna have a hard time to top the rockets here, but heck, give it a go!

 

By the way - are their any metallurgists out there who can help me with my problem in post #1?

 

I'm also trying to build a jet engine from a car turbine impeller, I just have to get my lathes set up to balance the little bastard. I've got some plans off the net, but its for a different sized impeller. Getting the combustion chamber not to flame out all the time will be the biggest hassle, I suppose. Apparently, using the right bearings, these little suckers can go to 100,000 rpm, delivering close on 20 pounds of thrust! I suppose ceramic bearings will be the order of the day. Take that, rocketboy!

[UncleAl]

A knife is art, technique, and materials. Pattern welding, Damscus (true wootz) and samurai steels, and talonite are among the really trippy materals when you get your act together.

 

http://www.carbideprocessors.com/Knives/

 

All of them have grain and must be worked to optimize grain orientation vs. the cutting edge. You'll never go back to 400-series SS or crude carbon steel.

[Boerseun]

UncleAl - I've got a couple o' damascus blades I'll send you some photos of. The trick lies in the different hardening layers coming out once your blade is done, and you dip the little sucker in some acid.

 

Basically, you take sheets of metal, heat-weld them together and whack the bejesus out of them, and then form your blade. Its a bit tricky, though, cause you only know you've got it right once you do the acid bath - which is the very last step.

 

The other thing I want to try is to make the acid-patterns (seeing as the acid eats the softer, less-hardened steel quicker to make the patterns) by heat-treating the blade in segments. I was playing around with making patterns in the steel through a different kiln-design, and heating the blade in segments. That also creates patterns in the acid bath, but getting fine patterns like damascus through heat-treating has only been done on the cutting-edge in the quenching process.

 

I'd like to hear your ideas on buckling, though!

[Boerseun]

What!? * GASP *

 

Cain't anyone o' you fellers here help me with them darn bucklin' blades?

 

[sTAMPS FOOT] pops a piece of chewin' tabaccy, spits, aims for the spittoon and misses [/sTAMPS FOOT]

[GAHD]

LOL, I'm reading some mettalurgy books to find out exactly that right now, Boerseun.

While I havn't found much more on what could be causing your warping (other than impurities), I am learning quite a bit about sand-casting Iron in your back yard. Smelting too.

 

Have you ever tried any of that? If you're going to splurge on a new kiln anyways; have you considered building a cupola(blast furnace) to do everything, including salting to get those impurities out?

[Boerseun]

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.

[C1ay]

Cain't anyone o' you fellers here help me with them darn bucklin' blades?

Try this.

 

First anneal and stress relieve after you have formed the blade by bringing it up to around 1800°F through out and cooling as slowly as you can. I will generally put tools that I want to do this to in the heat treating furnace, bring it up to temperature and then should it off and leave it to cool down over night. Alternatively I will bury them in sand to insulate them so they cool down slowly but this does not work well for tools with thin sections. This step should remove all of the internal stress in the metal that would tend to bend the metal.

 

Now heat treat. The whole piece needs to be heated as uniformly throughout as possible and then quenched as uniformly as possible. A similar piece that I encounter is a long drill bit I have fashioned. I try to use oil hardening stock but sometimes water hardening steel is needed for the hardest applications. To quench these I have a wire rack in the bath such that the surface is barely above the surface of the water. I place the heated bit on this rack and then add water at the edge of the bath so that the water rises to quench the entire length of the bit at once. If the water hits the bit in any one place before the rest it will bend at that point and step one is required again to get rid of the stress.

 

HTH,

[nkt]

Well, I'd pop round and show you how to stop it buckling, but...

 

Seriously, you wouldn't call a locksmith if you needed one, because he posted on the same boards as you?

 

Anyway, you didn't say which way the kinves tended to buckle? If it is upwards, so it curves upwards, like a fish would (Tail and head in the air) it is probably just because the side that is exposed to the air is cooling faster than the side that is still in contact with the warm oven floor.

 

I would suggest that you want to try the old Japanese way of doing this, which is to wrap the back edge of the blade in clay before heating, to keep the body a little softer and springier, while heating the cutting edge as normal. The clay should kep the heating and cooling more uniform during your long slow cooling off, preventing tension from twisting or curving the blade.

 

Edit: I should have added forging as one of my things, too. I've got a gas furnace that will melt brass/copper, but not steel. I also made a knife forge, you can see it at http://www.rubbertreeplant.co.uk/popup.php?ID=110