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Showing results for tags 'heat treatment'.
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Hi there, So I've just started out knife making and I think I overheated the blade during heat treatment. It has left it with some pitting as you can see in the photos, I was wondering if I have damaged the steel significantly or whether it is still use able and just affects the finish? Thanks
Hi everyone, I have seen on several you tube videos that people only bring the blade section up to red hot before quenching but the full tang of the handle is not red hot ? The knife I am building at the moment I can only get the blade and 1/3 of the tang red hot just wondering is it ok to quench with some of the tang not red hot or will the handle be ruined ? My forge is a brick forge with 1 x propane gas burner.
I couple people asked about the argon injection I'm using on my kiln, and while I don't have near enough experience with it I thought I'd put down what I've learned so far in this thread, and add to it as I figure things out. I got started on this adventure after talking to Kevin Cashen at Ashoken about decarb in electric kilns. He turned me on to the idea of injecting argon - I guess it's a fairly common practice in industry. My kiln is a Paragon 24 with a digital controller. It's chamber is 4 x 4 x 24, and it's pretty damn tight as far as gas leakage. I bought the Paragon Argon Injection kit which is pretty spendy, but it seemed like the only alternative at the time. Then I got an inert gas regulator, and a 40lb bottle of argon for $157 at my local gas supply. The total was about $400, but I'll explain how to do it for less. Knowing what I know now I would not have bought the Paragon kit. It is really just a flow meter and some copper piping: The injector is just a brass compression elbow stuck to some pipe that was welded to a square plate. I'm sure I could easily rig up the equivalent from Home Despot parts for about $20. You have to drill your own hole in the kiln and attach the injector with sheet metal screws anyways, so this part of the kit really does very little for you. The other part is the flow meter. My buddy who works with compressed gases (and oversaw this whole project) said this is the key part. It turns out however, that you can buy an argon regulator with a built in flow meter. So had I known I could have bought that and some piping for somewhere between $50-100, instead of the $250 I dropped. Live and learn. The other part you need is the argon tank. I bought a 40lb tank, but a 20lb would have been a better idea because it turns out you only need a tiny amount of argon. You also need a hose to run from the kiln to the regulator/flow meter. My buddy gave me one so I don't know what they cost, but I don't think it's a lot. The only hard part about hook-up is drilling the hole in the forge, and that's only hard if you are stupid like me and set up the injector like the Paragon kit showed. It meant i had to drill between the elements in the back, which was very tight. If I did it again I'd mount in through the bottom or top so I had no chance of hitting an element. How much gas do you use? the only reference I could dig up was this:Gas_Flow_Meter_Instructions_May2011.pdf It didn't come with the kit, it wasn't listed on the Paragon site, it was only through some serious googling that I found it hiding deep in the Paragon site. So following their instructions my kiln is 0.22 cubic feet, so if I want to turn over the atmosphere in the forge 5 times in the 30 minutes or so it takes to heat the blade I need to inject just a little over 2 cubic feet of gas per hour. So you'd think you'd set the flow meter to 2scfh. But the document also mentions that argon expands to 10x it's volume when it enters the hot kiln. So that means more like 0.2scfh on the flow meter. The meter goes in whole numbers, so it's very hard to get that little gas flowing. So that is where I am now, trying to determine how much gas to use. I'm starting from the bottom and working my way up. I tried my first knife with the flow meter just barely cracked open at about 1 scfh (which was as low as I could go). It had almost no scale. Unfortunately I didn't take a picture. Here's the result from giving the kiln a puff of argon at the start, and a puff at 15 minutes, and not having any flow: It's a bad pic of a 1084 chefs knife. There is some scale in the center, but it's less than without argon and thinner too. Next knife I'm going to try turning the flow up to 2 scfh and see if it completely eliminates the scale. It will also let me know if blowing that much cold gas in affects the heating of the blade. To put this amount of argon use in relation to tank size, 1 scfh of argon is 0.11 pounds. If my heat treat cycle is 30 minutes, then that means I should get about 727 heat treat runs out of the 40lb tank at 1scfh, a meager 363 if I go with 2scfh. I guess I could have gone with a 20lb tank pretty easily. I'll post more as I get this whole thing figured out.
Hello. I'm new to the forum, and relatively new to bladesmithing. At least new to creating knives with a little bit of knowledge. A friend of mine is using my forge (and what little I know) to make a Tai Chi sword from a piece of rebar. We first flattened it (meaning I held it and he did the beating--it's his sword, after all), straightened it, and he has been working it over on a belt sander to clean it up. I know rebar isn't the greatest steel for a blade, but it's got some spiritual significance for him. I understand how to harden it, but how do I temper the center of the blade without softening the edges? For heating, I have a coal forge, and an acetlyene torch. For quenching, water (I can make brine), and used motor oil. Thank you again, Buck