Fixing a Bandsaw Blade.


Traditionally bandsaw blades are resistance welded. Larger bandsaw machines have this facility built in so that the operator can cut internal profiles without starting from the outside edge of the work.

However blades can also be silver soldered or brazed and this has the advantage that the join doesn't need annealing afterwards.

A brazed Bandsaw joint

 

 

 

 

 

 

 

 

To braze a blade, a holder like the one shown on the right can be used. This was made from scraps of steel strip. The key feature was a milled edge which could be used to align the two blade ends. Each blade is held in place with a simple clamp and wing-nut.

The material in the middle of the clamp was removed to allow the join to be made without soldering the blade to the clamp.

The heads of the bolts on the underside could be used to hold the clamp in the vice.

Simple home-made blade clamp

 

Before brazing, the two blade ends should be ground at a matching angle to increase the surface area of the joint. This can be done of the bench grinder. It means the finished blade length will be shorter than before but this should be well within the tension adjustment of the bandsaw.

Grinding should be done carefully and wearing a glove if the blade is sharp. Also ensure the blade is lifted up from the grinding wheel after the cut and not pulled down as this can cause the grinding wheel to catch it and push the blade towards you.

Grinding blade end

 

 

 

 

 

 

 

 

Once the grinding is complete then the blade can be lined up and held in the clamp.

The straight edge of the jig is used against the rear edge of the blade to ensure the ends were lined up and accurately as possible.

The blade ends were pushed together to meet but not overlapped.

Blade join lined up and clamped in place in the brazing fixture.

 

 

 

 

 

 

 

 

Brazing the blade should be quick and easy. The joint should have a small amount of flux applied first.

The blade will have very little mass and so will heat up quickly with a small gas torch. Once glowing dull red, a small touch of the solder rod is all that will be needed to complete the joint.

The blade after Brazing

 

 

 

 

 

 

 

 

Once the blade has cooled, the braze should be filed to make it smooth and flush with the thickness of the blade.

Braze after filing flush

Close up of the finished joint

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