Hidden tang using all thread

whiteeugene

whiteeugene

Well-Known Member
I have a question on how to weld a piece of all thread onto a hidden tang blade that has a guard. I need to know when to weld the all thread on.

This is the sequence I think I need to follow.
1. Grind, heat treat and finish the blade.
2. Finish the guard and set it in place.
3. Wrap the blade in a damp cloth and weld the all thread.
4. Solder the guard in place.
5. Finish the handle and pommel.

Any suggestions would be great
 
I might be wrong

but

your gonna need to run through a few thermal cycles in the area you wielded or it will be weak
 
I have done this. Leave enough flat tang to fit the guard to, say 2". fit the guard, but, don't JB Weld or solder yet, then weld on the all thread. I make a slot about 3/8" deep in the flat tang that the all thread will slip into, then preheat the all thread and the tang to over 500f. If the blade is a high chrome steel I use 309 rod and if straight high carbon 7018. I weld a bit on the hot side. When done welding I thermal cycle it a couple times. Heat to red and let air cool, then not so red, cool and finally dull red and cool. Just like normalizing. I clamp the heat treated blade between aluminum plates when I am doing this. Properly done it is way stronger than any mechanical connection of the threads. If you used the same method and high temp silver braze, I think you would be plenty strong and could skip the thermal cycles
 
You need to add one step between 3 and 4. You need to anneal the tang after welding the bolt on or your going to have a week brittle tang. This is when you need to worry about keeping the heat off of the blade. You shouldn't get the blade too hot just welding the bolt on. On stainless blades I've started putting the blades in a can of water with the tang sticking out. Then with the shop lights out use a torch and watch my color to keep the tang at a dull red.

On stainless blades it takes some time to anneal the tang. I check the hardness from the bolt up to the recasso and like to see a gradual change from in the 40's RC up to full hardness at the recasso.

I've noticed just turning it blue or yellow does not effect the hardness at all, you have to actually keep it hot for at least 10-15 minutes in order to anneal it.

This brings up something I've wondered for some time, when guys come on the forums when they accidentally got a blade hot and turned the edge a little blue when grinding and had a dozen guys tell him it's ruined it I have to wonder if this is really so.
 
Or, do a no-weld attachment.

Somebody on this board, or another, came up with the idea of attaching all-thread to the tang by drilling a small hole (same dia as allthread) about an inch in from the end of the tang. You then make a v-cut in the tang to connect the end of the tang to the hole, removing a small wedge of metal. Removing this little wedge makes a channel for the all thread to sit in. Put it in place and then wack it with a hammer, and the all thread deforms enough to give you a solid mechanical bond.
 
The way I have done it in the past, first I use 5/16" threaded rod. before you even profile the blade notch the end of the billet 1/4"-3/8" so the threaded rod is a hammer fit and weld. also weld shoulders so there is no 90 degree angles. Then grind everything flat, even the threaded rod, so the guard can be persuaded into position past your shouldered welded area. Now go about business like it was one piece of steel. When you are done your pommel or whatever threads onto the flat rod. If you want to experiment take a piece of 5/16" threaded rod ground flat to 3/16" and thread a nut on it to test the strength, and if its at all possible use a fine thread bolt instead of all thread, fine threads are twice as strong as coarse.(have you ever seen a coarse thread head bolt on a motor? I don't think so) When I was a heavy equipment mechanic you constantly come across broken bolts where the only way to remove it is to torch it out. clean out the hole, retap and if you have half the threads install a new bolt. You would'nt do this all the time but it does work. just MHO..
 
Another option that I prefer, when possible, is to just turn the end of the tang down to appropriate size and use a die to cut the threads right on the tang. Then you won't have to worry about welding anything or annealing or whatever.

I realize this may not work all the time and all thread must be used instead. Just another approach.
 
Mike Carter said:
My "No Weld Butt Cap" thread is in the tutorials section http://knifedogs.com/showthread.php?4316-No-Weld-Butt-Cap. I often weld the rod but if your balde is thick enough this is a good alternative.
Click to expand...

Thanks Mike I have used that in the past and it works very well on full tang blades. I just wasn't sure about a hidden tang, if I leave the tang wide I should be able to follow the same process after I slip the guard on. I'll give it a try and see how it looks.
 
shakie said:
(have you ever seen a coarse thread head bolt on a motor? I don't think so)
Click to expand...

Actually yes, I can think of several motors that use course thread head bolts. :9:Big Block Ford was the first to come to mind since I have ran them truck pulling for many years and could put one together with my eyes closed. 9/16-12 head bolts.

On a serious note I realize what your saying and agree. When your limited to size and number of threads the fine is a stronger choice.
 
Ya got me Cliff, I'll keep that one in the memory bank.
Cliff Fendley said:
Actually yes, I can think of several motors that use course thread head bolts. :9:Big Block Ford was the first to come to mind since I have ran them truck pulling for many years and could put one together with my eyes closed. 9/16-12 head bolts.

On a serious note I realize what your saying and agree. When your limited to size and number of threads the fine is a stronger choice.
Click to expand...
 
Sorry if this is a stupid question, but I've never made a full stick tang knife (that's going to be changing soon).

Just out of curiosity, would it be possible to pin the threaded rod/bolt/whatever to the tang? I picture cutting a slot on the threaded rod and maybe taking a little thickness of the end of the tang. It seems like a couple 400 series stainles pins and maybe even some silver bearing solder would be pretty strong. Am I out of my mind, or would this be a reasonable solution?

BTW: I really like your tutorial Mike. I'll have to try that some day.
 
I don't see why pins wouldn't work just fine and I know knives have been made that way. Basically all the threads are doing is to hold the handle assemby together and/or attach the butt cap. Any stress would be against the handle. All of the methods mentioned will work especially if your handle cavities are filled with epoxy or AcraGlass.

Another way I often do stick tangs is simply grind a narrow portion at the end of the tang and thread the tang itself. If it is a thick enough tang you can drill it and tap it and just thread the all-thread into the tang with some epoxy, JB Weld or Loc-Tite.
 
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