Silver soldering/ brazing bandsaw bands

[mattthemuppet2]

I'm sure this has been covered before, but I figured I'd share what I learned. Lots of YT vids on this, most covering almost all of what I found out.

Anyway, first you need a jig to hold the ends of the band together and straight. I made mine out of some stainless angle, scrap and 1/4-28 wing nuts I had lying around

Grind both ends of the break square, then chamfer each end so the scarf is around 1/4" long. Coat both ends in liberal amounts of brazing flux (I used Harris Black high temp flux).

Align the ends in the jig and clamp down. You should have a very small void at either end of the overlap.

Heat the joint with a propane torch until the flux melts and the band turns red all around the joint. Carefully feed in some silver solder (45-55% silver, I used 50%) and play it along the joint. It should wick into the joint. If it doesn't melt, you don't have the joint hot enough. Only add enough to fill that void.

Grind off the flux and excess silver solder with a dremel or equivalent. It'll look something like this:

that was my first failed attempt, shouldn't look like that

Let it cool then sand about 1" either side of the joint until the metal is bright and clean. Put your torch on a lower setting and play it over the bright area until it starts to turn straw/ brown colour. You need to do this annealing step or the band might not be flexible enough and cause the joint to fail.

So after the 3rd or 4th attempt, I got the band to stay together!

and after the 4th or 5th attempt I got it to stay together while cutting metal! Woohoo! The joint looked a bit ugly, but it held

and then I could finally finish cutting through the piece of stock on the bandsaw

pretty darned pleased with myself!

 

[Ulma Doctor]

nice work Matt!

many moons ago, we made sawblades for meat cutting saws
we used a resistance blade welding machine and a purpose built grinder to remove the hump welding produced
i have bronze brazed meat cutting bandsaw blades in a pinch, but i wouldn't recommend it for metalworking saws

 

[Janderso]

Nice work on a unique subject.
Isn’t it amazing how the old saws came with a blade welder.
How the hell did that work so well?
I don’t go through enough blades to buy a 100 ft roll.
But, it’s really cool that you figured it out

 

[f350ca]

Have a jig very similar to yours, have silver soldered quite a few blades. Had been doing it for some time with usually good results. Then read you should anneal them, never had a blade hold if I annealed it. Quit annealing them and went back to probably 80% success rate. Need to make a beter jig to grind the bevels more consistently.

Greg

 

[mattthemuppet2]

thanks all, it was a pretty steep learning curve! I'm not 100% sure that annealing is necessary, as the first joint make well have broken due to the short scarf joint. But if the recipe holds, I'll keep doing it Maybe the fact that the 4x6 puts alot of twist through the blade might make a difference?

Greg - a jig to hold the ends for grinding the correct angle would be really helpful!

To celebrate I bought a nice Simonds 10/14tpi 1/2 x 0.025" band - 283 feet ahem, inches, for $10 off Amazon That's enough to make 4 bands for my saw!

 

[f350ca]

I've wondered if my annealing problem might have something to do with the solder Im using. Have had the coil for decades and can't recall what the silver content is. If the melting point is on the low side, maybe annealing it affects the bond somehow?
I've started buying pre made blades as of late. Can't find stock as cheap as the welded blades now.

Greg

 

[mattthemuppet2]

Maybe, but I'm about as far from an expert as you can get!

For me this was mostly about being able to get out of a pinch when a band breaks, plus I've been having a run of broken bands and it starts to get expensive. We'll see how this works out, but it was a neat learning experience. I have a carbide boring bar to make soon too!

 

[brino]

Great price for the new blade stock.
Thanks for sharing your experience!

283 feet for $10 off Amazon That's enough to make 4 bands for my saw!

70 foot long blades?! That is a biiiiig saw!


I smell a typo...........................

-brino

 

[jwmelvin]

a jig to hold the ends for grinding the correct angle would be really helpful!

I thought the idea was to put the ends together and grind so the angles match. That way the actual angle doesn’t matter.

 

[Flyinfool]

Matching is more important that the actual angle, to a point. There is a range of acceptable angles. Off hand I do not know what that range is.
Using a jig just means you will have consistent angles and there for consistent results.