Recommendation? Extending a Damascus hidden tang

R

Ron Romer

Joined
Mar 11, 2020
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I bought a couple of blanks from a knife maker who got out of the business due to some health issues. My favorite is this Damascus blank that has a beautiful pattern, exceptional all-purpose profile and very tight solid laminations. The only problem is that the tang was a little short. It's meant to be a hidden tang. I ground ithe shoulders of the ricasso area to get another 3/8" of tang length but I need 1.5 inches more of tang length to run to the end of a handle. If I can extend the tang, then I'll grind and thread the end for a pommel.

I had a piece of mild steel in my hand that I was about to grind into the right shape for a welded on extension. Before I started welding, I second guessed the choice of materials. I was thinking it may be important to use a higher carbon steel and then to anneal the seam to relieve any stresses from the metals (and weld fill) of dissimilar carbon content. I assume the metals will shrink differently as they cool.

The good news is that there is enough tang length already (4-1/8") that I have options to limit heat transfer to the blade itself. (Blade is already heat treated). I'm thinking copper or aluminum vise jaws or wet rags.

I'm confident in my welding ability but I need advice on material selection and any subsequent heat treatments. I'm not a smith and I just haven't done anything like this before.

Best advice to extend the tang?
 
DO NOT WELD on steel that can be hardened like a knife blade. That’s a sure fire way to crack the joint. As soon as you weld and the puddle cools it becomes glass hard with very large grain. I have had to weld onto carbon steels at work and it usually requires a nice hot preheat and then a thermal cycle or two after to remove any brittleness. Your best bet is to A: forge the tang out longer and then anneal and thread with a die. Option B is to braze or silver solder the tang extension onto the stub. Do this by scarfing each end and do a clean braze job using flux.

But how ever you decide to attach the tang extension please stay away from the welder. With that said you could use a tig welder to braze. Just don’t liquify the steel, that’s how you get joints so brittle thy have just about zero structural integrity. If I was buying a knife and found out that was done I would pass on it. There are much better ways to accomplish this without being lazy and grabbing the welder.
 
Wait why are you wanting to run all the way through the handle? Are you threading a nut or cap onto the back side? Depending on the material used for the handle I try for at least 2/3rds of the handle length as tang. If the handle material is weak like cross grain cut wood then I will try and go further. But most of the time as long as the handle material is solid and the tang is large enough you will not have any problems. If the handle material is in question you can drill it out and reinforce it with steel inside full length. Then fill with epoxy and insert your tang. Now everything is tied together. But with a 4”+ tang I would use it as is and not mess with extending it. The original knife maker who made the blade was not in the wrong in his design choices. I would leave it as is and select a good sturdy handle material to go with it. When ever I have seen hidden tangs fail is because thy ground it down to narrow at the shoulder not because it was to short.
 
With all due respect to JT, many/most of us weld an extension on the tang. I know I have done it at least 100 times.

Use plain welding steel (mild steel) or any pieces of scrap carbon steel you have around. You do not need to match the bade steel exactly. We aren't building rocket parts.

After the weld is done, temper the blade for an hour at 400°F. It will be fine from there on.

As JT pointed out, as long as the handle material is strong, the tang only needs to go 1/2 to 2/3 the way down the handle.
 
Stacy E. Apelt - Bladesmith said:
With all due respect to JT, many/most of us weld an extension on the tang. I know I have done it at least 100 times.

Use plain welding steel (mild steel) or any pieces of scrap carbon steel you have around. You do not need to match the bade steel exactly. We aren't building rocket parts.

After the weld is done, temper the blade for an hour at 400°F. It will be fine from there on.

As JT pointed out, as long as the handle material is strong, the tang only needs to go 1/2 to 2/3 the way down the handle.
Click to expand...

To play devils advocate
Just because something is common practice does not mean it’s the best or even the right way to do something. People can do things how thy want and that’s the beauty of this craft. Me personally, I stay away from the welder. I have seen to many failures in my line of work (machinist for 3 Sawmill’s) on welds that where on steel that should not have been welded onto. Like I said before it can be done but requires pre heating and some cycling afterwords.
 
Bevel the ends to be welded to allow for 100% weld. Preheat to ~400’f and after it’s welded post heat to ~1300 2-3 times. Must be done before heat treating.
Use a torch for the pre and post heating.

Hoss
 
Ron Romer said:
I bought a couple of blanks from a knife maker who got out of the business due to some health issues. My favorite is this Damascus blank that has a beautiful pattern, exceptional all-purpose profile and very tight solid laminations. The only problem is that the tang was a little short. It's meant to be a hidden tang. I ground ithe shoulders of the ricasso area to get another 3/8" of tang length but I need 1.5 inches more of tang length to run to the end of a handle. If I can extend the tang, then I'll grind and thread the end for a pommel.

I had a piece of mild steel in my hand that I was about to grind into the right shape for a welded on extension. Before I started welding, I second guessed the choice of materials. I was thinking it may be important to use a higher carbon steel and then to anneal the seam to relieve any stresses from the metals (and weld fill) of dissimilar carbon content. I assume the metals will shrink differently as they cool.

The good news is that there is enough tang length already (4-1/8") that I have options to limit heat transfer to the blade itself. (Blade is already heat treated). I'm thinking copper or aluminum vise jaws or wet rags.

I'm confident in my welding ability but I need advice on material selection and any subsequent heat treatments. I'm not a smith and I just haven't done anything like this before.

Best advice to extend the tang?
Click to expand...
Use map torch on end of tang .They are powerful and will heat end of that tang fast to red color ,don't worry nothing will happen to blade temper .Do that several times , then weld extension and heat with torch one more time again ....
PS.Now when i think about welding....wasn't the winner once on Forged in fire guy with welded blade :D
 
Last edited:
JTknives said:
To play devils advocate
Just because something is common practice does not mean it’s the best or even the right way to do something. People can do things how thy want and that’s the beauty of this craft. Me personally, I stay away from the welder. I have seen to many failures in my line of work (machinist for 3 Sawmill’s) on welds that where on steel that should not have been welded onto. Like I said before it can be done but requires pre heating and some cycling afterwords.
Click to expand...
I agree with all you write JT ,many times i have tried to save some parts /in my real job/ but never successfully ...... but end of that tang probably is not even hardened
 
Natlek said:
I agree with all you write JT ,many times i have tried to save some parts /in my real job/ but never successfully ...... but end of that tang probably is not even hardened
Click to expand...
It might not be hardened but it’s hardenable steel. So once it liquifys from the weld and cools fast from the colder steel around it it will become brittle and most likely the grain will be blown out. Now if you used a torch and did a few thermal cycles on it then sure.

I did a cool tang extension on a sword. There was a hole in the every end of the tang. I then made a threaded hook that wound go into the hole and a pommel threaded onto the end. It sucked it down nice and tight and gave the tang a pivot I needed to get around the arc shape of the antler inside.
 
I appreciate all of the input. I'm hearing some different opinions on welding. I just wanted to clarify that the blade is already heat treated. I don't want to do anything to compromise the existing treatment. I'm not a smith and I do not own a forge. I have an elaborate woodshop with some basic metalworking equipment and I do some limited metal fabrication. I've only made knives for personal use or for gifts to my family and I'm super picky about doing the best possible work. Otherwise, I would just buy a knife. That's why I'm asking for expert advice before I dive into this knife build.

I can preheat with a torch or an oven before I weld but I don't want to do anything to compromise the existing grain structure of the blade itself. If I should do some type of annealing treatment after welding, please let me know specifically what you think is the best treatment.
 
I have had good success with braze/silver solder. I selected a bolt with fine threads, suitable length, and an appropriate steel (usually Stainless) and cutting the head off at an appropriate length, slotting the bolt for 1/2"-1". I then can slide the slotted bolt over the tang stub at the desired angle and attach it with a minimal amount of heat to get a solid joint.
 
The tang is 1/2 inch wide at its widest point. It's not wide enough for the keyhole method (which sounds COOL). If the tang only goes 2/3 the length of the handle, then I don't want to creat stress risers by cutting holes for pinning it. I don't think I could get larger than a 1/8 pin, anyway. I don't own a forge, so I can't forge a longer tang. It's already heat treated, so the advice about fixing things before the heat treatment won't help.

I planned a brass (shaped) guard and pommel with a cocobolo handle. I'll use a couple of layers of black/white micarta liner for a pinstripe between the brass and cocobolo.

Right now, either the brazing or welding sound like the best approaches. I'm favoring the brazing, which I haven't done before but I have hundreds of hours of experience soldering. I understand the concept very well but have no experience with the silver or brass. I know you want your metal very clean and you have to heat the parts till the brazing material flows into the joint.
 
Yeah, 1/2" would be pushing it for keyhole. I usually use the 1/4" threaded rod, but have used thinner, and have done it on 5/8" wide tangs, but usually wider.
I always do it before HT and do a fair bit of shaping with files, which you clearly can't do now.
Sounds like you have a plan.
 
Ron Romer said:
The tang is 1/2 inch wide at its widest point. It's not wide enough for the keyhole method (which sounds COOL). If the tang only goes 2/3 the length of the handle, then I don't want to creat stress risers by cutting holes for pinning it. I don't think I could get larger than a 1/8 pin, anyway. I don't own a forge, so I can't forge a longer tang. It's already heat treated, so the advice about fixing things before the heat treatment won't help.
Click to expand...
If your knife would be something like this .............you need one pin to secure handle , and that pin /3mm.pin is more then enough/ in middle of handle can not be stress riser in any way .....
R4yDKhL.png
 
Natlek, thank you for the drawing and recommendation. The tang in your drawing starts wide and tapers down. Mine is a uniform width at 1/2" for it's full length. For such a short tang, I'm still reluctant to make a weak point. I may be overly worried but it doesn't matter at this point.

Incidentally, I cut a piece out of an old pair of hedge shears to make an extension. First, I ground the existing tang to taper the end a bit. Then, I ground the extension so it fit it so it perfectly fit perfectly into the taper like a rat tail along the existing tang with about a 5/16" butt fit at the end. The fit was so close you couldn't see light in between. The parts were sanded perfectly clean bright metal just minutes before brazing. Then, I used a specific type of silver brazing alloy called Muggy Weld SSF-6. This silver alloy rod was awesome.

I isolated the ricasso and blade from the heat of brazing, using heavy pieces of of plate aluminum used as vise jaws. The blade was wrapped in wet cloth. I heated the extension and the existing tang with mapp gas to dull red (in low light) and covered the seam and surrounding areas with molten flux from the Muggy Weld rod. The brazing flowed readily into the seam and created an extremely strong bond when the steel was a very subtle (almost imperceptible) dull red.

I made some fine adjustments with the supports to ensure perfectly straight aligmnent with the blade and existing tang. After two reheats for fine adjustments, the brazed extension was perfectly straight and the joint was ground/brushed clean to give a VERY tough extension. The temper of the damascus was unchanged in the critical area where the tang and ricasso come together. The blade itself never got hot.

Now the extended tang has been ground to 1/2 wide and 0.150 thick and about 10 inches long. I'm really amazed at the strength of the joint. I will easily be able to grind the end down to thread it for a pommel. Problem solved.

Thanks everyone for your input. I wish I knew how to post a picture. It really is amazing how well the brazing worked and the damascus pattern is pretty spectacular. The wisdom you offered was helpful and taught me a lot.
 
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