A Good Example

[Elvis]

Here is one that had a loose pin that allowed just enough space for the odd wear pattern to start years ago. The worn area of the tang is deep enough to cause the knife to lose its snap even if it hadn't worn a divot into the backspring. Both of these together made for a blade with no action at all.


TIG welding is the only method I've found that is precise enough to replace the metal without heating the entire blade to the point of it losing it's temper. That's the plan for these two pieces.


I know I've described this problem before and the procedure that I use to fix it, but I thought this time I'd supply pictures of the process as we go. I should be headed to the welding shop within the next few days. Careful grinding on the tang and backspring should restore the action on the old knife. Give me a few days and the next pictures should be of the repaired pieces before installation.

[jerryd6818]

Are you going to weld and re-drill the pivot hole or will you just drill it slightly oversize to get rid of the out of round and use a larger pin?

Steady as she goes on this one.

[knives-are-quiet]

Here is one that had a loose pin that allowed just enough space for the odd wear pattern to start years ago. The worn area of the tang is deep enough to cause the knife to lose its snap even if it hadn't worn a divot into the backspring. Both of these together made for a blade with no action at all.


TIG welding is the only method I've found that is precise enough to replace the metal without heating the entire blade to the point of it losing it's temper. That's the plan for these two pieces.


I know I've described this problem before and the procedure that I use to fix it, but I thought this time I'd supply pictures of the process as we go. I should be headed to the welding shop within the next few days. Careful grinding on the tang and backspring should restore the action on the old knife. Give me a few days and the next pictures should be of the repaired pieces before installation.

Please show this procedure as the welding is done.
I am very interested in a new fix for knives with this problem.
I have seen this same ware pattern on many knives over the years.
My only solution was to replace the blade and spring or grind everything and blend the spring which changes the shape of the knife in the end as I would have to reshape the back bone of the knife after re assembly.
Thanks for sharing this procedure Bob.
I look forward to seeing how it is done.
J W

[orvet]

I encounter this problem far too often.
I will be watching to see your fix.
Thanks for taking the time to show your process!

[Elvis]

Are you going to weld and re-drill the pivot hole or will you just drill it slightly oversize to get rid of the out of round and use a larger pin?

Steady as she goes on this one.

Steady as she goes is right. First I'll trace out the exact shape and size of the remaining intact piece of tang to give me a guide as I regrind and normally there is no problem with the hole. TIG welding uses a rod (in this case) that is about 1/16" and the guy that does my welding can add the needed metal without filling the hole. Its what he does for a living and he's gotten very good at it. My biggest concerns will likely be grinding the blade back to 1 or 2 thousandths less than the width of the backspring and making sure the backspring grinding is as seamless as possible. After that, it should be a straight-forward reassembly since we're using the original handle material.

If the hole were to see some added metal, I'd take a small Dremel attachment (after grinding to the correct width) and try to bring the hole back to match the other blade in the knife. I'm not a fan of enlarging the pin size except as a last resort. It is a good option that is nice to have as a fall-back should problems arise, but I try to save it if I can.

[jerryd6818]

My biggest concerns will likely be grinding the blade back to 1 or 2 thousandths less than the width of the backspring and making sure the backspring grinding is as seamless as possible.

Do you have access to a surface grinder. Those puppies are the cat's pajamas for accurate thickness.

[coffeecup]

Now there's a thought. I saw a very nice little benchtop surface grinder a while back, just couldn't figure out a use for it! The throw was only about 4", but 4" is enough for knife work. I may have to try to swap the owner out of it. I wonder if he needs any old pocket knives . . .

[Elvis]

Unfortunately all the grinding is done by hand and eye, but I do have the help of my trusty micrometer. Here are the pieces after getting them welded today (It took a bit longer than I thought since the welding shop was closed for the long weekend). The next step is the grinding and I'll post pictures before they're installed.

[orvet]

I changed this to a Sticky so we could find it easier if it takes Bob a while to finish the project.

Also because I will be fishing in Montana for 2 weeks and want to be able to find it when I get back! (Just kiddin').

[Elvis]

I changed this to a Sticky so we could find it easier if it takes Bob a while to finish the project.

Also because I will be fishing in Montana for 2 weeks and want to be able to find it when I get back! (Just kiddin').

Have fun in Montana. Also, our friend knife-nut has a small Case lobster knife that I recently used this same procedure on and I believe I sent update pictures to him that he can post if he kept them.


Edited to remove useless info.

[knife-nut]

I changed this to a Sticky so we could find it easier if it takes Bob a while to finish the project.

Also because I will be fishing in Montana for 2 weeks and want to be able to find it when I get back! (Just kiddin').

Have fun in Montana and since the wife had to go into the hospital on an emergency basis last night, it could take a tad longer than originally thought. Also, our friend knife-nut has a small Case lobster knife that I recently used this same procedure on and I believe I sent update pictures to him that he can post if he kept them.

Sorry Elvis, I did,nt get pictures with the update. They would be interesting to see. The blades have great snap now. Awesome repair job. Mark.

[Elvis]

Thanks Mark. Checking back I did take pictures after it was taken apart, but none after that. Here's what it looked like with the offending parts rubbing the way they had been for years.




You can (barely) see the spring sticking up off of the liner and the flat piece of tang that remained in original condition. This was my template for grinding after the welding (I just traced it onto a piece of paper) like I did on the knife this thread is about. Sometimes not enough of the original shape remains and another blade from the same maker can be used or since the measurements aren't critical to the thousandth, trial and error can give you a good fit if you're careful not to remove too much. As little as 1/64th of an inch (or less) extra metal on the round part of the tang will put extra snap back that the knife has never seen before. Caution should always be used as too much extra metal could result in a broken backspring. As good as my welding guy is, we've never gotten a welded backspring to hold once it had been broken into two pieces. Never.

[Elvis]

Got some real progress to show today. The first pic is of the preliminary fit together which allowed me to give it a check to make sure the snap was okay.

The next one shows the same thing with all the parts lined out for assembly. The initial fit used the old pins which weren't long enough for putting the knife back together.

The third pic shows new pins holding her in place now.

The next two are just different angles of the knife before peining the pins (which I hope to do tomorrow).


A test run of the blade action looked like good news all the way around. We'll soon see if that still holds true when it's finished.

Questions or comments? Anybody think I'm nuts for going to all this trouble?

[Gunsmoke47]

Looking Great Bob! I don't think you're nuts at all on a pre 80 Case. I respect knife mechanics a lot. Now if you were going to that trouble on a Rough Ryder, I might think you were a little nuts! Smoke

[just bob]

Is there none of the instant weld products like JB Weld or Liquid Weld that a novice can make this repair with? I don't have a welder and they show grinding these products to spec after they have hardened. Also there was some stuff on TV for a long time that I think was called Aluma Weld that you used with a small propane torch. Will anything like that work?

[Elvis]

Good questions, but the JB Weld just isn't strong enough and would chip apart the first time the blade was opened. As for the Aluma Weld, I have some and although it works great with aluminum, it won't stick to steel and since it's softer, I'd worry about it wearing out too fast. As far as the Rough Riders, I've worked on a couple for a friend who only has use of one hand and sends me his knives to have the action weakened. The brass is too soft and plyable, like they aren't really made to be worked on. Except for his case, I don't work on them as I consider them throw-aways (let the hate mail begin).

[muskrat man]

looking good Bob.

I've tried JB weld and Bob is right, it peels right off the tang when the action is worked for the first time. I have used silver solder to make tang repairs but even it will wear as it is softer than the backspring steel. Weld is about the only way to go. Now, that said. I have a theory, as I have yet to actually try it but I see no reason it wouldn't work. Cut the tang down a lot and dovetail in a larger piece of steel and solder it in place (like the old Robeson mastercraft series with the bronze tang inserts) and shape to fit. I see no reason why it wouldn't work but it would be very time consuming, having someone lay a bead of weld on the worn areas would be much more realistic.

One thing I am curious about though is the temper, how is it affected by the weld? I worked on one switchblade that a guy welded in a chip in the tang that was preventing it from locking open. When I worked it down to fit it was VERY hard, like freshly quenched steel that hadn't even been drawn back. I always wondered if he quenched it in something immediately after completing the weld. The metal was all down to a bare finish almost like a bead blast look. maybe he dunked it in a pickling solution to remove the scale after the weld was complete?

[Elvis]

I received a PM asking what rods my welding guy uses and I had to plead ignorance. He asks me if he's welding stainless or carbon steel and takes it from there. The welds don't seem that much harder than the rest of the tang, but without proper testing, it's hard to know for sure. In this case since the tang and backspring were both welded I think it's safe to assume they now have the same hardness in that spot so uneven wear shouldn't be a factor.

As for your welding guy Kaleb, the person who sent me the PM mentioned certain rods that produce a welding bead that is around RC 58. Since modern (factory) blade heat treating methods leave the tang a tad softer than the blade area, I'm wondering if 58 would be too hard and begin to wear on the backspring. I'd also like to mention that he is always careful to clamp the blade or backspring in a vise with only the part that needs attention sticking up. This allows the vise to act as a heat-sink helping to prevent heat transfer to the blade area so we don't lose temper.

This method has worked well for me and is the only way I've found to correct this problem short of using new parts which often just aren't available on a lot of the older knives. Your biggest hurdle in using this method will most likely be finding a welder with the talent and patience to do it. I highly recommend bribery with folding cutlery.

Edited to add that the knife has been reassembled and just looks like the last pictures of it with the pins peined. End of lesson I suppose, but I'll be here for questions and I hope this has been helpful to someone.

[vieu101]

Looking good Elvis...you gunna post pictures of the knife I sent you LOLOLOLOLOLO

[Elvis]

Looking good Elvis...you gunna post pictures of the knife I sent you LOLOLOLOLOLO

Yours had the same problem, but works great now. Although your knife was a bit newer, the main blade had lost all snap. All it takes is a loose hinge or "pivot" pin and the uneven wear will start. "Keep 'em tight and oiled" would make a good motto for this situation, don't ya think?

[0078]

Bob I'm going to give this a try did you mig, tig, or braze I'm try it on some junk knifes first. Ill keep you posted, thanks for the thread. Greg

[Elvis]

Bob I'm going to give this a try did you mig, tig, or braze I'm try it on some junk knifes first. Ill keep you posted, thanks for the thread. Greg

TIG.

[orvet]

Bob,
If I recall correctly you posted some work-in-progress pics of the TIG welding on one of the first blades you did. Do you recall where that post is?

I have recently discovered a guy in my town who is willing to try it.
I just wanted to check how you did it.

Thanks,
Dale

[Elvis]

I think the only ones I've posted are at the start of this thread Dale.

[orvet]

Thanks Bob.
I should have looked back through the thread.

The pictures showed me what I was looking for.
Thanks again.