Having problems soldering guards

[Will W.]

First, I've been asking a lot of questions lately. Not trying to be annoying (and I hope I do not come off that way!) I just know that I have discovered something here that I love with a passion, and I truly appreciate the knowledge that is distributed here.

Second, I have read everything I can get my hands on regarding soldering on guards. I would not ask without checking. Even after reading a lot of this info, I'm still having trouble with it. The blade I'm working on is a tanto, essentially, and I wanted to put a small guard on it. I've only ever done one guard before, and I MIG welded it, and i think it turned out awful, you could see the small spots of incomplete fusion, and the lines of the edges of the weld after grinding. So, I tried practice soldering a few pieces today. Just two pieces of mild (though the actual blade is 5160) with plumbers 95/5 solder, and the rosin flux typically used with it, propane torch as heat. I slotted the on piece to fit around d the other, simulating a guard. The fit was pretty tight. The actual soldering went great, but there was no structure. I could tap it with a hammer, and it broke right off immediately (after it cooled, or course.) I applied the heat from the underside, like where the tang would be, and used just enough heat to get it done. Any idea why it was so weak? Was it the solder I used possibly? Is there a better solder to use for the situation? Thanks in advance. 

[Michael Cochran]

Have you tried putting something behind the practice guard to simulate a handle. If you did that and it still came right off I'd be worried but if you didn't have a handle (which is the way it reads) there's not much supporting the guard other than the solder. 

[Will W.]

Actually no, I did not try that. Overlooked that little detail. I'll give that a try next time I'm in the shop. Thanks for the reply. 

[will52100]

I don't do much soldering anymore, if my fit is tight enough I do a solderless press fit with JB weld as a sealer.  The shoulders keep the guard from going forward, the handle keeps it from going back, the solder or JB weld keeps out moister.  Done rite, both have plenty of strength without a handle and should not just tap loose.

First, lose the plumber's solder and get something like Stay Bright silver solder.  You can solder with lead/tin, but it'll grey out and doesn't like higher alloy steels, especially stainless, and you need a stronger flux.  Next, make your joint as tight as possible with a little room at the back, and surgically clean and bright.  Sounds like your heating correctly, the way I do it is to clamp the blade sideways and heat from the back side of the guard with a strip of solder on the front side.  I take a strip of solder, about 1/32" diameter, lightly run it through some 220 or 320 sandpaper to take any oxides off, bend into a U shape and fit as close to the joint as I can.  Wet with liquid flux, it comes with the kit, and heat till the solder flows.  Don't over heat.  After all is said and done and I've scraped the guard close with a brass chisel and clean up a bit I boil in a can of water with baking soda to kill any flux residue.  If you don't you could have trapped flux and it'll weep out and cause rust spots in the future.  After that I finish everything up.

The aggravation of going back over a blade and solder joint to finish and having to neutralize acid flux is one reason I've went to solderless guards.  The only one I don't do it on is the Loveless style full tang guard that fits into a notch on one side and is open at the top, I haven't been able to get as close a fit as I want for solderless yet.

[gote]

I assume that you know that the guard on a real tanto is held buy the hilt

[ThomasPowers]

and the habaki !

[gote]

and fuchi and seppa if we want to get technical

[ThomasPowers]

If you make a 3 line 17 syllable poem about hilting parts of a japanese blade would it be seppaku ?

[JHCC]

1 hour ago, ThomasPowers said:

If you make a 3 line 17 syllable poem about hilting parts of a japanese blade would it be seppaku ?

Seppa, habaki,
Tsuba, fuchi, mekugi,
Ito, kashira.
 

[ThomasPowers]

E I, E I, O

Quote

 

 

[JHCC]

On 1/31/2017 at 4:59 PM, ThomasPowers said:

E I, E I, O

 

E I, E I, O-1

[Will W.]

Gote

I did not know that actually. Japanese techniques and styles are pretty foreign to me (for lack of a better term.) I just wanted to try one. Thanks for the clarification though. 

Will52100

I figured the solder and flux were probably improper. Naturally though, it was all I had around the shop at the time. I'll try some different solders in the future, like the one you recommend. I appreciate the in depth response, thanks. 

 

[will52100]

One other suggestion I learned recently at a hammer in, use a sharpie to color all around the face of the guard except maybe 1/16" where the ricasso goes.  Apparently the sharpie will keep the solder from sticking and make clean up a lot easier.  Haven't tried it yet, so not sure how well it'll work.

[Will W.]

Interesting. I'll keep it in mind. 

Have you seen it done anyway? The only problem I can think of is the heat simply cooking the sharpie ink away. This is just speculation though. Thanks for the tip. 

[will52100]

I imagine it does cook it away, but would leave a residue that the flux has a hard time eating away, or at least that's the theory.  Most likely will turn to carbon and tarnish the surface, and as much as I hate to sand tarnish off, I hate sanding solder off even more.  Lora Schwarzer was where I got the idea from, she makes beautiful Scagal style knives.

[Frosty]

Just use a solder stop and heck, buy the correct solder. It's fun to play with products made for other than what we're trying to make them do but it's at risk to the project. It's to the maker of course up but what do you want, a good working knife or time playing with solders? Playing with solders is what test coupons are for.

The information about doing these things correctly is commonly available though you'll have to spend some tie reading the knife making section here or elsewhere. None of the questions you're asking are mysteries or need to be figured out unless you want to.

Frosty The Lucky.

[Will W.]

Frosty

I agree. I enjoy improvising, when it is appropriate. I assumed from the start the solder I was using was incorrect, but it's all I had, and I wanted the opinions of the people who have far more experience than I on the subject. 

I also did read through a lot of what I could get my hands on regarding soldering the guards on. That's where the small bit of knowledge I have on this subject came from. That's why this great archive of info is here, after all. I was just looking for specific answers regarding this specific situation. I meant no disrespect. 

[Frosty]

I don't know which solder or the correct technique to use. I'd have to read some and probably call the local welding supply and ask. The guys at the local welding supplies and I know each other well, I've sent them to their books more than once. Then I tell them what works and doesn't.

It's a lifelong learning curve.

Frosty The Lucky.

[gote]

If you want to call it a tanto, perhaps you should look up how they are made in the world where the word is appropriate. They are made in the same way as a katana just smaller.

You have not shown any pictures so it is difficult to have some good idea about it. I would assume that if the guard is a thight fit it would be easy to use any solder that creeps in by capillary action. When you examine the pieces, Where did it come loose? Did the solder not "take" on the blade?  or on the guard?  A thight fit over the whole surface is very important when soldering or brazing (How is your filing?) and you need to have CLEAN surfaces. With a good fit and a guard that is not too flimsy you would even be able to use tin solder. You heated on the tang. Was the guard hot enough?  

[will52100]

The solder is less important than a flux that will etch the metal.  Regular old past flux won't cut it on higher alloy and stainless steels, and a good solder like stay brite will not only flow well and have more holding strength than lead solder, but it stays bright and shiny longer instead of turning grey.

I've never used a solder stop, but I would be willing to bet that the sharpie trick works well as it came from a maker that I respect both as a person and there craftsmanship.  If they say it works then I'd be willing to give it a try.  I have a feeling it's pretty much doing the same thing.  Also, I have sharpies on hand, would have to go and buy solder stop.

The argument on tanto's is unending.  What your talking about and others are is the American tanto vs. the traditional.  Or as some would call it, a knife with a tanto point.  I love the traditional blades, and really don't much care for the American tanto, but if that's what you want to make then there is no rules saying you can't, so call it what you want and make what you want.

[ThomasPowers]

They make hard solders and fluxes for use with stainless alloys but they are WAY TOO HOT for soldering a guard onto a blade and will mess up the heat treat big time.  So be careful if you ask at a welding supply place for solder for stainless....

[Frosty]

1 hour ago, ThomasPowers said:

They make hard solders and fluxes for use with stainless alloys but they are WAY TOO HOT for soldering a guard onto a blade and will mess up the heat treat big time.  So be careful if you ask at a welding supply place for solder for stainless....

You'd have to solder SS before heat treating the blade.

OR, make the pieces interference fits and sweat them on. Say make the guard (I don't know any of the Japanese names, barely know the American ones actually) Anyway, make the guard a few thousandths too small to slip over the tang, make a SLIGHT shoulder on the tang the guard has to slip over. Chill the blade and tang in a dry ice alcohol bath and warm the tang to say 300f in the toaster oven. Quickly drive the guard into position on the blade. When the temps equalize the guard isn't going anywhere.

Interference fitting has zero effect on heat treatment.

Frosty The Lucky.

[Will W.]

Gote

I'm not trying to make a world class, traditionally made, japanese masterpiece. I just wanted to try that style.

 I didn't put any pics up because I was just trying to solder two pieces of mild, and they are in some random scrap bin by now. The fit was tight. Both metals were pretty clean. It "took" onto the blade and guard. The guard was hot. By heating from the tang, I meant that I slowly wove my flame from tang to guard, right in the corner where they meet, to heat evenly. I tried to solder it three times and it broke off from the guard once and the blade twice by just tapping the guard with a hammer. Had it broken from one or the other every single time, it would have pointed me to where the problem originates, but it seemed random, hence me asking on here.

Will52100

I think this is likely. The flux is cheap, and frankly, so is the solder. It's meant for copper pipe, not mild steel. Honestly though, I figured it would work. I've read up on the stay brite, and it sounds more like what I'm looking for. I'll give it a try sometime. Along with the sharpie trick. Like you were saying, I have sharpies everywhere haha. 

Thomas

I will keep that in mind. Thank you.

Frosty

I assume you meant to heat the guard in the oven? So as to cause it to expand?

That's fascinating though. I can honestly say I would have never thought to put a guard on this way. Haha. 

 

 

 

[ThomasPowers]

I heat shrunk a head onto a warhammer about 1992; but left the handle protruding a bit so I could "rivet it on" when it worked loose.  Still waiting and it's seen a lot of abuse! (I mean why have a war hammer without *hitting* stuff with it!"

[will52100]

I am no expert by any means on stainless, do only a handful every so often as I much prefer carbon steel.  Anyway, I would not sub zero a blade and slip a hot guard on, might be OK, but could cause the stainless to fracture at the junction from thermal expansion.  Like I said, it might work, but my experience with cryo shows that the critical point is not the cooling down, but the warming back to room temp where if it's shocked it likes to break.  Should work fine at regular refrigerator/freezer freezer temps and warming the guard.

I'm not up on stainless braze, I use silver braze on some applications like adding on to a stick tang, but all I've used flows in the 1400-1500 deg range and the last stainless blade I heat treated was at 2000 deg. so it would not work to braze the guard before heat treat, and would damage the heat treat post heat treating.  I have seen stainless guards made of the same material as the blade TIG welded on with strips of blade metal prior to heat treat.  Good idea to check the temp ranges to make sure everybody is on the same page as to solder/braze.