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Soldering brass
- Thread starter MBurks
- Start date
Stacy E. Apelt - Bladesmith
ilmarinen - MODERATOR
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I assume you are using a low temp solder, like Stay-Brite or TIX.
The first thing is to prevent excess solder. Use the smallest amount possible. I hammer the solder into a thin ribbon, then clean the strip with a few strokes through a folded piece of 120 grit sandpaper. Clean the guard and blade like it was a surgical implant. Assemble and flux with the proper flux for your brand of solder. Use sufficient flux. Apply heat gently. Too much heat makes the flux burn, makes oxides which prevent the solder from flowing, and makes the solder flow away from the joint. Use the heat sparingly and remove the heat as soon as the solder starts to flow. Coerce the solder down the joint with a soldier pick. I use a titanium pick, but a piece of 18 gauge piano wire with a needle point works just as well. Drag the point down the joint while applying just a little heat from the other side. The solder will follow the pick point.
After soldering, remove any excess solder with a brass graver. Any scrap piece of round/square brass stock can be put in a wooden dowel type handle and sharpened like a flat graver. It will cut away the solder, but won't mar the blade or guard.
I have a piece of 1/4" square bronze in the one I use. It gets a bit sharper than a plain brass graver.
Once you have removed the excess, carefully sand or buff the guard to remove any thin remnant of the solder. If all the solder isn't removed, the spot will turn dark with exposure to the air. Putting a layer of tape on the blade before doing any abrasive processes prevents Oopsies. I use soft 3/4" bristle wheels in my flex shaft and ZAM polish to clean up the joint. Then I buff first with 1" muslin buffs in the flex shaft, then with a 6" fine combed cotton wheel spinning at around 500-700 RPM on a low power buffer.
The first thing is to prevent excess solder. Use the smallest amount possible. I hammer the solder into a thin ribbon, then clean the strip with a few strokes through a folded piece of 120 grit sandpaper. Clean the guard and blade like it was a surgical implant. Assemble and flux with the proper flux for your brand of solder. Use sufficient flux. Apply heat gently. Too much heat makes the flux burn, makes oxides which prevent the solder from flowing, and makes the solder flow away from the joint. Use the heat sparingly and remove the heat as soon as the solder starts to flow. Coerce the solder down the joint with a soldier pick. I use a titanium pick, but a piece of 18 gauge piano wire with a needle point works just as well. Drag the point down the joint while applying just a little heat from the other side. The solder will follow the pick point.
After soldering, remove any excess solder with a brass graver. Any scrap piece of round/square brass stock can be put in a wooden dowel type handle and sharpened like a flat graver. It will cut away the solder, but won't mar the blade or guard.
I have a piece of 1/4" square bronze in the one I use. It gets a bit sharper than a plain brass graver.
Once you have removed the excess, carefully sand or buff the guard to remove any thin remnant of the solder. If all the solder isn't removed, the spot will turn dark with exposure to the air. Putting a layer of tape on the blade before doing any abrasive processes prevents Oopsies. I use soft 3/4" bristle wheels in my flex shaft and ZAM polish to clean up the joint. Then I buff first with 1" muslin buffs in the flex shaft, then with a 6" fine combed cotton wheel spinning at around 500-700 RPM on a low power buffer.
I have one more question.
I have been fitting the guard tight ,and peeking the bottom so I have a press fit, then hearing the tang with the blade upright in a vise , wet rag wrapped around the blade.
All my studying so far seems to back this up as the preferred method, but the heat seems to travel through the guard faster than the blade.
Am I doing something wrong?
I have been fitting the guard tight ,and peeking the bottom so I have a press fit, then hearing the tang with the blade upright in a vise , wet rag wrapped around the blade.
All my studying so far seems to back this up as the preferred method, but the heat seems to travel through the guard faster than the blade.
Am I doing something wrong?
Stacy E. Apelt - Bladesmith
ilmarinen - MODERATOR
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I don't suggest wrapping a wet rag around the blade, as this acts as a heat sink, making it hard to get the blade past 212F. If the blade is heated evenly along with the guard, they both come up to the flow point of the solder together. Since this is below the temper of the blade, no harm is done. This is why some folks use a heat gun to solder their guards.
The solder flows from the point oapplication toward the heat. Heat the blade and guard from the blade side, not the tang. Heat the blade a tad more than the brass guard if necessary. The brass has a higher coefficient of heat than the steel. Again, if they are heated evenly, they both come up to the flow point together.
The solder flows from the point oapplication toward the heat. Heat the blade and guard from the blade side, not the tang. Heat the blade a tad more than the brass guard if necessary. The brass has a higher coefficient of heat than the steel. Again, if they are heated evenly, they both come up to the flow point together.
One thing I've found helpful in preventing solder "overflow" stuck onto the blade or front of my brass bolsters (on chef knives) is to 'mask' the areas where you don't want solder. The logic: if, to get solder to stick, the surfaces must be clean -- well, then, if they're not clean it shouldn't stick, right? Research turned up using (a) a paste of yellow ochre or red jewelers' rouge powders (both iron oxides), and (b) welders' soapstone stick. So far I found soapstone to work pretty well; yellow ochre not as much; haven't tried rouge.
That said, seems pretty smart to try hard to avoid having too much solder in the first place - no excess, no spillover. I've had good results with a tip from the 4-part BoseKnives vids on YouTube: tinning the bolsters in advance. Clean & flux the mating surfaces, heat 'em up, apply some solder to get an even thin coating. (Bose does a practiced 'fling' to get excess off; I've got mine in a vise so I've used a piece of 1/16" brass rod to kind of wipe it off if I overapply the solder.) Then re-clean everything; pin, peen, and/or clamp it all together; and heat it up (again, slowly!). Put wee bits onto the joints so you can see the flow point happen and to fill any gaps at the edges. I'd also recommend positioning it so any overflow runs down onto the tang or spine/belly - those you can sand/file off and clean up, vs. at the base of the blade where it meets the bolster (DAMHIKT).
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Hard Le$$on$ You Can Avoid Learning Your$elf: silver solder (I use Harris Stay-Brite w/ Stay-Clean flux) seems almost perfectly engineered to be impossible to remove excess cleanly other than with brute grinding - it's somehow both gummy and hard as hell. After just the obvious small needle files (cf: "gummy"), I've tried rubber abrasive grinding points, diamond riffle files, tiny strips of ceramic abrasive paper glued around popsicle-stick edges, heating the area and trying to suck it up with copper de-soldering wick - you name it. Generally I've come to the conclusion that it's not worth it "chasing a mistake down the rabbit hole"* Better to just scrap the bolster (e.g. bandsaw it off; grind remnants off; touch-up the blade surface; re-drill the pin holes, etc.) and re-do with a new one -- or just scrap the whole blade and move on to the next.
* my term for the trap of trying to fix something, then fix the fix, then fix that, then swear a lot, etc., instead of just being smart by accepting reality, cutting losses, and backing up, at the beginning.
That said, seems pretty smart to try hard to avoid having too much solder in the first place - no excess, no spillover. I've had good results with a tip from the 4-part BoseKnives vids on YouTube: tinning the bolsters in advance. Clean & flux the mating surfaces, heat 'em up, apply some solder to get an even thin coating. (Bose does a practiced 'fling' to get excess off; I've got mine in a vise so I've used a piece of 1/16" brass rod to kind of wipe it off if I overapply the solder.) Then re-clean everything; pin, peen, and/or clamp it all together; and heat it up (again, slowly!). Put wee bits onto the joints so you can see the flow point happen and to fill any gaps at the edges. I'd also recommend positioning it so any overflow runs down onto the tang or spine/belly - those you can sand/file off and clean up, vs. at the base of the blade where it meets the bolster (DAMHIKT).
-------------------------------------
Hard Le$$on$ You Can Avoid Learning Your$elf: silver solder (I use Harris Stay-Brite w/ Stay-Clean flux) seems almost perfectly engineered to be impossible to remove excess cleanly other than with brute grinding - it's somehow both gummy and hard as hell. After just the obvious small needle files (cf: "gummy"), I've tried rubber abrasive grinding points, diamond riffle files, tiny strips of ceramic abrasive paper glued around popsicle-stick edges, heating the area and trying to suck it up with copper de-soldering wick - you name it. Generally I've come to the conclusion that it's not worth it "chasing a mistake down the rabbit hole"* Better to just scrap the bolster (e.g. bandsaw it off; grind remnants off; touch-up the blade surface; re-drill the pin holes, etc.) and re-do with a new one -- or just scrap the whole blade and move on to the next.
* my term for the trap of trying to fix something, then fix the fix, then fix that, then swear a lot, etc., instead of just being smart by accepting reality, cutting losses, and backing up, at the beginning.
Bill DeShivs
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A #2 pencil can be used to mark areas where you don't want solder to flow.
I just realized that a Sharpie marker could probably be used with more precision on mirror polished parts. Will have to try it, but I see no reason it wouldn't work.
I just realized that a Sharpie marker could probably be used with more precision on mirror polished parts. Will have to try it, but I see no reason it wouldn't work.
- Joined
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They wrote you all about how to soldering the guard.
I add only this: after soldering, prepare a pot full of water and saturated with bicarbonate, bring it almost to boiling and dip the blade. In this way you will go to neutralize the acidic effect of the flux. It 's very important, otherwise after a few months or even years later you can find the blade with rust!
I add only this: after soldering, prepare a pot full of water and saturated with bicarbonate, bring it almost to boiling and dip the blade. In this way you will go to neutralize the acidic effect of the flux. It 's very important, otherwise after a few months or even years later you can find the blade with rust!
Bill DeShivs
Knifemaker / Craftsman / Service Provider
- Joined
- Jun 6, 2000
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A simple dip in water with a little ammonia will neutralize any acid flux.
Stacy E. Apelt - Bladesmith
ilmarinen - MODERATOR
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On damascus, I do the boil in water thing. On mono-steel blades, I just rinse well with hot water, spray down well with Windex ( ammonia and water) and rinse again.