Howdo you attach a new brass guard to an old hardened blade

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Permalink Reply by Terry Waldele on April 21, 2010 at 22:18

What a great question! I have tried filling the excess space in the slot with solder, and it doesn't work (for me, anyway).
My first recommendation would be to get some brass bar stock and make a new guard for the blade with the right sized slot.
If you don't want to take that project on, I would suggest that you use a brass brazing rod to fill the excess space between the tang and the guard slot, and braze the guard to the blade at the same time. Before brazing, you will need to clean both pieces thoroughly with file and sandpaper, then with acetone and liquid flux, before brazing them together. Then, build up the brass brazing rod "filler" a little "above" the surface of the guard, quench it, and when it's cool wrap the blade in electrical tape and file the brazed surface to match the face of the guard, sand the surface with a sanding block with progressively finer grit metal sandpaper, and polish. Be sure to use heat sink paste on the blade and guard around the braze.
If you don't have a gas welder, and the excess space is very small (like 1/32nd inch), you might try peening the slot all around the tang to fill in the space, using a cold chisel, but that will require a lot of resurfacing work on the guard afterwards. If you choose this method, be sure to wrap the blade with electrical tape before you peen the guard.
Hope this helps.

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Permalink Reply by Gary Moore on April 22, 2010 at 12:46

Thanks for the reply Terry. I have just realized that I ordered guards for this particular blade that are way too wide to fit (slot/blade thickness). I am going to order a different guard that will hopefully be a tight fit. When I do recieve the corect guard; should I try to braze it or silver-solder it to the blade? (I have done neither; but, I am wanting to learn and I think that I have a couple of local resources.)

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Permalink Reply by Terry Waldele on April 22, 2010 at 22:35

Gary, silver-soldering is my preference, but only if there is absolutely no slop in the fit of the guard to the blade/tang. If it's a really snug fit, soldering, if done correctly, will work fine. But be sure to use heat sink paste on the blade before you start soldering. Also, make sure you don't get any of it in the guard slot. (I would use a Q-tip to apply it.) If it's not a really snug fit, brazing is the way to go. Brazing can be problematic, though, if you haven't done much of it. If you prefer, you can make a new guard from scratch, but be prepared to spend a lot of time on it, especially if you cut the slot with a drill and files. If you go that route, you have to be really precise in removing the brass from the slot square and true. If you have a metal-cutting scroll saw, that can really speed up the work, but it requires as much or more precision in cutting the slot. (It's just so easy to overcut the slot unless you are extremely precise and patient to cut within your scribed lines, and continually check for squareness and straightness. If you decide to make a new guard from scratch, I would strongly suggest that you attach it by brazing, so you can fill in any gaps between the slot and the blade/tang. Before brazing, apply heat sink paste with a Q-tip to the blade, making sure none of the paste gets into the slot. Also, apply brazing flux sparingly to keep the brazing rod metal from bleeding out and bonding to the blade or tang. Otherwise, you will have to clean up the excess brass, and that ain't no fun! Good luck!

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Permalink Reply by Gary Moore on April 23, 2010 at 11:33

WOW!! Thanks for the reply Terry. I am planning to order a pre-fab guard with the slot as close as I can get to the blade thickness. I will probably try my hand at silver-soldering after I recieve it. There is just TOO MUCH difference in the slot width and the blade thickness to be able to securely attach the guard that I have. Any tips that you may have for soldering will be graciously recieved with many thanks. I can weld (stick) and cut with a torch; but, I have never braized nor silver-soldered. Is it feasible to braze the slot back to a solid piece and then make a new slot of the correct dimensions? Would that require too much heat that it would ruin the guard?

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Permalink Reply by Terry Waldele on April 24, 2010 at 1:12

Attached is a copy of a soldering tutorial that may help you. It's from NorthCoast Knives' website.
This file is in .pdf format readable with Adobe Reader. Hope it helps.

Attachments:

• Soldering Tutorial.pdf, 104 KB

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