Help soldering broken bandsaw blade


Obviously I'm doing something wrong here as my joints are brittle
and don't hold worth squat. I ground the ends of the blade to about
45 degrees and cleaned the ends with sandpaper. I put on plenty
of flux and wedged a small piece of silver solder in the scarf joint.
Both ends are held in a jig so nothing moves during the soldering.
The saw blade is 3/16 wide and .025 thick. I'm using oatey 53013
silver solder. I'm using a propane torch w/ pencil tip burner.
I've tried heating just till the solder melts & flows, and hotter, up to
the blade turning a cherry red. Nothing worked.
So what am I doing wrong? technique? Wrong solder?
Art
Reply to
Artemus
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Never having done that, I feel qualified to advise that this guy *has* done that:
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Scroll about 75% down the page.
[Spoiler] The scarf must be *very long*; cut at a shallow angle. This guy advises a 1/2" long lap, not 0.025" long.
--Winston
Reply to
Winston
I've only welded blades, not brazed them, but I'm going to guess the blade is cooling fast enough to quench it, making it brittle. After you've made the joint remove it from your jig, shine it up with sandpaper, then heat it gently by waving your torch flame around 'til the steel turns blue. You've tempered the steel enough that it should no longer be brittle.
Reply to
Ned Simmons
Winston fired this volley in news: snipped-for-privacy@news2.newsguy.com:
Winston! Winston... Winston...
50313 is a lead-free plumbing solder. It's NOT "silver solder" in the sense of brazing alloys, even if it might contain some silver (which Oatey does not state in the specs)
First of all, get some 'real' silver solder -- the stuff you buy in the Forney section of an ACE hardware, or at a welding shop. Second, be prepared to see the metal red before the solder will flow. The Oatey 53013 will flow at about 700F, which will barely make the blade smoke, much less glow dull cherry red.
LLoyd
Reply to
Lloyd E. Sponenburgh
Silver solder (low silver content) or silver braze (high silver content)?
Wes -- "Additionally as a security officer, I carry a gun to protect government officials but my life isn't worth protecting at home in their eyes." Dick Anthony Heller
Reply to
Wes
IIRC We always welded them and then did some annealing process to soften the weld so it wasn't brittle by giving shots or current after the weld and grind. Been a long time since then...LOL
I've only welded blades, not brazed them, but I'm going to guess the blade is cooling fast enough to quench it, making it brittle. After you've made the joint remove it from your jig, shine it up with sandpaper, then heat it gently by waving your torch flame around 'til the steel turns blue. You've tempered the steel enough that it should no longer be brittle.
Reply to
Josepi
Aha! Thanks Winston, that's a nice site. He's using 1/2" on a .035 blade so 3/8" on my .025 ought to be in the ballpark. Now to figure out how to do it - the Dremels out for sure. I've give it a shot on the grinder or beltsander. Art
Reply to
Artemus
Ill come in here, Ive silver brazed my band saw lades for 40 yrs. as linked, the scarf joint needs to be minimum 3/8ths in long, you do this scarfing on the top wheel of a band sander set up vertically. Jig as also described, but bend the lower blade end up a little and he top blade down a little. You need to use a 50% if you can get it silver solder in foil form, 5 to 10/1000 in thick. cut a piece exactly to size, place between the 2 blade ends. mx up some easyflo flux paste preferrably s/steel grade, apply arround the joint area. heat gently till the flux goes clear, continue to heat till the joint goes a dull red under the flux and the silver solder flows to wet the scarf area. allow to cool clowly. Remove from jig, fftle up and grind both sides of blade so that the thickness is the same overall, as you said .025 thick. dont over tension the saw blade. Hope this helps. Ted. Dorset UK.
Reply to
Ted Frater
It is soldering and not brazing that I'm trying to do so I don't *think* I need the 'real' stuff. I'm attempting to do what these guys are doing without buying their package.
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they use a butane torch I doubt they really are brazing. Art
Reply to
Artemus
If you don't have foil, a clean hammer face and anvil surface can make some foil for you with a blow or two. :)
Wes
Reply to
Wes
That's kind of what I was thinking to make the scarfs. Thanks. I don't have an OE torch. Can I use propane with the 50% silver solder? Mapp? Mapp/oxy? Art
Reply to
Artemus
Heh! I asked Ernie about reassembling my 10" chef's knife with *Real* silver solder. He advised the use of the *barely* silver solder rather than the real stuff because of possible temper loss.
Ergo, I figured that my Oatey 5% lead-free, cadmium-free would be plenty good for bandsaw blades.
Now I'm confused. :)
Relurking.
--Winston
Reply to
Winston
:Xns9D93DEAA4F54Blloydspmindspringcom@216.168.3.70...
Lloyd is right. You're using a soft solder and it=92ll never hold for this job. The real silver solder that you need is a hard solder and melts at a brazing temperature. Usually you use oxy-acetylene for silver soldering. You just have the wrong tools to do this job properly. See:
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Reply to
Denis G.
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As they use a butane torch I doubt they really are brazing.
You can count on it. True silver solder is not gonna melt with that joke kit. At the very least you will probably need propylene fuel, if not oxy/acetylene. Quit clowning around and invest in a welder.
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nb
Reply to
notbob
For a piece that small your propane torch should work . Dad silversoldered that way - though not bandsaw blades . Bigger pieces he put on mom's gas range plus the torch .
Reply to
Snag
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As Lloyd and Ted mentioned, the higher silver content solder (ca. 45-50%) is probably what you really want.
Beware though!
Compatible flux is critical. Match the flux to your solder WRT temperature or be very frustrated! DAMHIKT
--Winston
Reply to
Winston
You CAN silver solder band saw blades, very well, with a propane torch and hard silver solder. Been there, done that with never a break. You don't have to weld them.
CP
PS: I have only done it up to 1/2".
Reply to
Pilgrim
This is the best flux for silver solder. You need the Stay-Silv white. Note the temps. A propane torch should get you there. Still better off with the welder. Good luck.
nb
Reply to
notbob

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