There are 2 ways . You can cut a bevel arross the thickness and
silversolder them or you can build or buy a resistance welder (similar to a
spot welder) that fuses the ends together under compression . And here's a
link to one made by Ernie Liemkuhler that uses a TIG welder to fuse the
Hold the two ends together, one atop the other, with the teeth facing
in opposite directions, and grind the ends straight and even. Freehand
is fine, the angle across doesn't have to be 90 degrees because if the
blade edges are held parallel when ground their 'supplementary' angles
will add to 180 degrees.
Clamp the ends in the welder and set the energy level for the blade
width. Weld, then anneal the joint.
Grind down the welding flash on either side only enough that it
doesn't foul the guides. Run the grind scratches lengthwise so they
don't concentrate tension stress.
The grinding wheel should be dressed straight. I prefer a pedestal
grinder to do the ends, though the little one on some blade welders is
more convenient to remove the flash.
Folding them into three smaller loops:
I couldn't preview it with my XP, IE8 and dialup.
The 1-1/4" x 16' blades for my sawmill are a real challenge to fold. I
unfold them by throwing them onto the lawn.
Be aware that blade welders are rated for the maximum blade width they
are capable of welding. It would be wise to purchase a welder with extra
capacity. Avoid the china blade welders.
Is your spool bi-metal or single material? If a single
material, there are lots of welders which clamp the two blade ends to
large electrodes, and when you hit the button, the ends are slammed
together while a lot of current is pulsed through them to melt them into
one piece. There is typically a grinder mounted in the same thing to
remove welding flash so it will pass through the guides properly. You
also have an "anneal" button, which puts a lower current through the
joined ends (it gets at least to red, and you give in successively
shorter pulses so it cools slowly.)
However -- many of these don't put enough current to handle the
bi-metal blades (an edge of HSS welded onto the main backing and that
takes more current to weld the HSS part. Usually it will work as long
as your blade is a width or two below the maximum for the welder.
Another approach is to take the two ends, grind a shallow angle
onto each so they partially overlap, and then use a torch to join them
with silver solder. I've read (here) from people who made their own
jigs to both hold the blades to grind the same angle on both, and to
hold them together for the Silver Soldering.
If you have a big vertical bandsaw (and *you* likely do), those
often have a blade welder mounted in the left column, so you may already
have that -- it is just a matter of learning to use it. One reason for
that is so you can cut a (good) blade, thread it through a hole drilled
in a workpiece, weld it back together, thread it back into the bandsaw,
and use it to cut out a hole which does not reach the outer edge of the
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