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View Full Version : silver soldering vs soldering of bandsaw blades



Elninio
04-15-2013, 06:55 PM
Can regular electronics solder do the job?
http://softsolder.files.wordpress.com/2009/07/cimg3641-resistance-soldering.jpg

darryl
04-15-2013, 07:03 PM
Not enough strength, and poor bonding.

GEP
04-15-2013, 07:10 PM
Silver solder is the only way if you solder. Make your self a fixture to hold the bade together. Grind the ends on a curf

GEP
04-15-2013, 07:23 PM
I had some plans for a home build blade welder some where. I look a little harder maby your interested

J Tiers
04-15-2013, 08:49 PM
In a word, NO. Not even close.

Silver soldering is weak enough, no way 60:40 lead solder is likely to work for more than a few seconds if you can even tension the blade.

It probably WILL "wet out" OK on the steel, so it will "bond"... the problem is the lead won't stand up to the stresses.

Plumbers no-lead is stronger, but still not good enough. Might last a bit longer. Welding, or silver solder if you must, is the way to go.

SGW
04-15-2013, 10:16 PM
Nope. Even if you succeed in grinding fairly long and tightly overlapping tapers on the blade ends, the amount of overlap area for bonding is quite small. Silver brazing (a.k.a. silver soldering) can provide the required strength if done well, but there is no way ordinary tin-lead solder is going to. There has to be a minimal amount of solder so the blade thickness isn't increased; otherwise the joint will bind in the saw kerf.

vpt
04-15-2013, 10:50 PM
Local hardware store rewelds my broken blades for like $5.

JoeLee
04-16-2013, 12:31 AM
The guys are all dead on, electrical solder will never work.
I've silver soldered my blades in the past and it always worked well for me. I've also TIG welded them too but you have to aneal after welding or the joint will break.

Your jig should have a gap where the blade halves meet or most of the heat will be sinked out or you may end up sticking it to the jig if you use sliver solder.

JL.....................

Elninio
04-16-2013, 12:37 AM
No stores around here to weld bandsaw blades, but would like to know how many amps to weld bandsaw blades. How many?

JoeLee
04-16-2013, 12:45 AM
No stores around here to weld bandsaw blades, but would like to know how many amps to weld bandsaw blades. How many?

I never paid much attention to the amp setting, using a foot pedal it was what ever it took to fuse the blade halves. Maybe 10 amps ???
Also when welding you don't want a gap in you jig or you'll burn through. It's the one instance when you do want something under the blade to prevent fall out.

JL.....................

Elninio
04-16-2013, 02:37 AM
I never paid much attention to the amp setting, using a foot pedal it was what ever it took to fuse the blade halves. Maybe 10 amps ???
Also when welding you don't want a gap in you jig or you'll burn through. It's the one instance when you do want something under the blade to prevent fall out.

JL.....................
I burnt a 20A output transformer today, it's gotta be more than that?

Elninio
04-16-2013, 02:49 AM
I had some plans for a home build blade welder some where. I look a little harder maby your interested

got one in the making, it's almost done, just gotta rebuild my transformer

JoeLee
04-16-2013, 09:07 AM
I burnt a 20A output transformer today, it's gotta be more than that?

What type of welding caused your transformer to burn out???? I doubt it was TIG. I would guess your trying to duplicate some form of resistance or spot welding like a true band saw blade welder would do.

JL.........................

J Tiers
04-17-2013, 08:45 AM
Depending on the size of the blade, I'd W.A.G. the current as easily in the hundreds of amps..... Spotwelding runs to thousands of amperes...... but has more possible conduction paths for heat to leave the joint (all directions in the sheet metal, plus into the tongs). The saw blade may not need as much since it has less conduction of heat away.

Spotwelding 0.030 aluminum for electronic device cases took about 2500A, as near as I can tell from the ammeter and ratio on the spotwelder we use at work

JoeLee
04-17-2013, 09:13 AM
Spot welders for band saw blades also have timers that cut the power before the joint is blown away. I believe the time is calculated by the width and thickness of the blade and the power requirements.

JL.................

bosox
04-17-2013, 02:45 PM
You can never go wrong with 40% silver content. IMHO, I don't think soldering band saw blades will save you money.

Evan
04-17-2013, 04:29 PM
This is what a spot welding transformer looks like.

http://ixian.ca/pics10/xformer1.jpg

http://ixian.ca/pics10/xformer2.jpg