Threading Hidden Tangs??

R

raythebigfoot

Joined
Sep 12, 2007
Messages
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Pretty simple question actually; for those of you that work with hidden tang knives with a threaded tang do you thread the tang before or after heat treat?

Wanted to do it before because it will be easier but I am not sure whether it will get messed up in the heat treat. (Steel is CPM154 if it makes a difference) Thanks!!
 
I weld a long piece of all thread on the end of mine, with a nut threaded on it. It goes into heat treat like that. After it is hardened, I then run the nut up and down the threads to clean them up and straighten out anything that happened in hardening and then I temper it with the nut on. Oh, I almost forgot, I also do a few normalizing cycles prior to hardening to take out stresses from the welding process and make the weld stronger. I haven't had a threaded tang break at the weld since going to the normalizing steps.

I then cut it to length and carefully hand file a little chamfer on the end of my now threaded tang. When I remove the nut from the all thread, it straightens out and cleans up the threads real nice.
 
I also weld on all thread, but, you can thread the tang if you like. I have not had problems with threaded material heat treating. I wouldn't tong the threads or anything while red hot. I have heat treated internal threads also and they also worked fine after. I use an electric oven and get little scale. The stainless like you have take some serious temps to harden but, most do them in a stainless steel foil packet and in that case you should have no scale. Good Luck Jim
 
Using stainless you will have to thread the tang before heat treat because when yu get it back from the heat treaters I do not think it would work well (just like drilling all holes before heat treat)...Welding or brazing on threaded rod works just as well and is a very acceptable way to make a threaded tang.

Good Luck,
Bruce
 
I am not much of a welder unfortunately, but I am willing to try new things. Can I weld onto CPM154 and then still heat treat it? If so, can someone explain the welding method to be in detail so that I can try it. Thanks!
 
I make a lap joint with the rod, and tang, install two 1/16" pins through the joint, then silver braze it with Brownells Silvaloy. 1175o flow temp if I recall right. Easily done with mapp gas, or even propane with the Mapp torch head.
 
I would suggest the Silver braze to attach the rod to the tang after heat treat untill you learn how to weld.
Bruce
 
Thread the tang then heat treat. After heat treating and tempering you can freshen up the threads with your die with no problem.
 
I agree on the soldering over welding. Soldering is way more forgiving than a welder and way strong enough for a tang thread and like bikermike says you can thread first, just use your grinder to get the tap tip close to the correct od, thread and harden. Stainless, can be welded. Most knife steels would need a preheat to at least 500 before welding. This will help keep stresses down. I would probably use 309 rod. When finished I always head the welded area to a red heat and allow to slowly cool. With stainless I would go a bit hotter, longer and then wrap in kaowool and let cool. I wouldn't expect that much stress in a small weld zone.
 
It all depends on how you do the Heat treat. All the answers above are very good and practical. I have brazed sections of steel bolts to tangs, etc. but if are using Oil-hardening or water-hardening steel, and you do your own HT, you have the option of not hardening the tang at all. I leave the tang very well normalized (not annealed) and then simply file it up by degrees to accept a thread cutting die. You can do it by eye, no rocket science required. A good die will actually swage the steel a bit ahead of the die as well as cut. A narrow tang threaded for a nut is a very good way to make a knife, as is peening the tang over a pommel plate. It is much simpler not to have to piece the tang together. BUT of course if you are using an air hardening tool steel or air hardening SS, then you will have problems. I suppose you could heat sink the blade and try to apply enough heat to soften the hardened tang enough to use a threading die on it. I would try that before I resorted to fabricating the tang of different pieces.
 
foxcreek..he is using cpm154....that is why we told him to thread before he heat treated.

Bruce
 
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