Silver soldering band saw blades

[garyphansen]

What are the secerets of the black art of silver soldering the ends of a band saw blade together. Also what is the best way to cut bulk band saw blade to length? Is using a band saw blade welder better than silver soldering?
Gary P. Hansen

[Jpfalt]

Step 1 is to grind or file a taper on both ends of the blade. On an .031 thick blade, the chamfer was about 1/4". The chamfer has to be clean.

You need a jig that will hold the blade in lline and the chamfers ovelapping. Borax flux and silver solder is slipped between the two blades. Then heat until the solder wicks over the joint.

When the solder is wicked through the joint, quickly grab the joint area with a pair of pliers to squeeze the joint.

At this point the joint will be brittle because the pliers quench the bandsaw steel. You then heat the joint with a torch until it just starts to show very dull orange in near total darkness.

Then the excess solder can be filed off and the joint filed so that it is smooth on both sides and the back. The teeth in the joint are also sharpened at the joint.

[gizmo2]

excellent response! I would add one step, and that is to measure the thickness of the joint, after it is completed, and grind it until it matches the rest of the blades' thickness. I haven't broken a silver solder joint in about 30 blades now since I've taken care to get the joint thin enough.

[darryl]

While you're at it, try to get the tooth pattern matched so there's no irregularity in the cutting action.

I found that after grinding the angle and the overlap on the ends of the blade, a pre-heating and cleaning made it easier to silver-solder it after that. If I just cleaned without heating the ends first, it was harder to keep the junction clean and get a good solder flow.

It pays to get or make a decent jig to hold the blade for soldering. Try not to clamp the blade too tightly, as it needs to slide a bit as it cools to lessen the stress on the solder join.

[electromotive17]

This boric acid flux will it work on all types of silver solder,and where can i buy it.

[garyphansen]

What about cutting bulk band saw blade to length and welding vs silver soldering?
Gary P. Hansen

[Your Old Dog]

I cut mine with a Dremel and one of those thin brown wheels they have. It's likely overkill but it does work well. Maybe there is an easier way that I don't know about. Using the Dremel you can cut them on a bias using a guide if you wanted to.

[garyphansen]

What about welding vs silver soldering?
Gary P. Hansen

[x39]

Gary, at one of the shops I worked at years ago, I used to get the guys in the welding department to TIG weld my bandsaw blades for me, so yes it can be done. The joints were very durable, I don't recall ever breaking one. If memory serves me right, I think they said they were using nickel rod.

[skeeter]

Hey Electromotive17,

You can find the flux an any welding supply.

Might even find at a home center.

[portlandRon]

I cut mine with a pair of tin snips then grind the ends square.
Welding down with a blade welder.

[Jpfalt]

Boric acid flux is just borax in water. You can get boric acid at a pharmacy, use 20 Mule Team Borax mixed with water, or go to a welding supply and get silver soldering flux. They all work. I have even picked up anhydrous borax from a chemical supply company.

Silver soldering blades works well for wood cutting blades, but I question the quality of thhe results for metalcutting blades because you soften the teeth on a carbon steel blade through the length of the solder joint and heat affected zones on either side of the braze. On a bimetal blade it shouldn't make much difference because the heat treat on the HSS teeth isn't affected much.

Tig welding and resistance welding work well for both wood and metalcutting blades as long as the weld and heat affected zones get tempered well enough to avoid brittleness, but not enough to soften the cutting teeth.

[Your Old Dog]

I get my blades from a supplier who welds his own for metal and wood. So far I can't see much differance in cutting ability due to softer metal. I suspect the secret might be to get in and get out. Take a lot of time and you might ruin a large enough section to cause weakness to become apparent.