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.
I used to silver solder them, with mixed results. Some held for the life of
the blades, some let go in minutes.
I have welded blades on the Do-All saw at work, and it is AMAZING. No
training, just clamped a blade in there, set the dial and pop, beautiful
weld. If you can get one of these, do it.
I have an antique German blade welder that apparently has home-made blade
clamps. They are pretty good, but not quite right, and sometimes one blade
end climbs up on the other one. I keep fiddling with it, and it gets a bit
better. But, I can usually get a weld that will work for a couple months,
but they often fail before the blade is completely worn out. I make my
blades extra long so I can re-weld them a couple times before they get too
There are a ton of posts in the archives (Google groups) on welding band
saw blades. There are 2 ways: welding with a dedicated machine and
silver brazing. For occasional use, the machine is too expensive and
brazing is just as good, but slower. For details, search the archives.
Sounds like a candidate for a HSM project. I wonder how much current
blade welders deliver. Don't know if a 105-amp MIG would be enough
but a re-wound microwave oven transformer surely would be.
On Wed, 14 Sep 2016 12:15:17 -0400, "Jim Wilkins"
This email has been checked for viruses by Avast antivirus software.
Before I snagged a German blade welder on eBay, I had built a very bad
homebrew one. I found a transformer that had a lot of available "window"
still open, and wound a couple turns of battery cable through that, and made
up a clamp for the blade. It worked remarkably well for a total jury-rig
setup. I know if I had kept on working on it, it could have made decent
blade welds. The transformer in a Do-All welder is remarkably small, but
obviously purpose-built for the job.
Looks like 1 to 3 volts at 100 to 200 amps. Looks like a primary of
354 turns of #15 or two paralleled #18 wires, tapped at 150 and 200
turns. Laminated core center post area of 3.65 in^2. Secondary
winding of four rectangular formex wires each .105 x .165, 4 turns.
On Thu, 15 Sep 2016 17:36:34 -0500, Don Foreman
This email has been checked for viruses by Avast antivirus software.
Which one -- the home-brew or the Do-All?
From personal experience with an import version of the welder
(came from eBay a few years ago), the weld pulse is too quick to get a
reasonable reading with a clamp-on ammeter. Add an electronic meter
which can measure the peak current very quickly and you will do better,
but that is typically lab bench equipment, not hand-held. Maybe a
storage oscilloscope, or a digital one and you could look at the
waveform out of the clamp-on probe.
Now -- if you operate it from perhaps as low as 6V or so, you
can measure the input and output voltages and calculate the turns ratio.
Then, from that, you can look at the fuse rating in series with the
primary to calculate the maximum current out of the secondary. Assume a
very low resistance load. Remember, the blade forms a complete loop as
it is being welded, so the resistance between the clamps and the ends
has to be a lot lower than the resistance though the blade the long way.
I did that to a spot welder I had in the lab Used my 1000 amp HP clamp
on into a HP meter.
The current was just shy of 1000 amps and the voltage was 1.5 open
That was a 1/4" spot weld into a sheet of Al.
I think in the way back mode of this group, a home brew was made and
worked. Maybe Don made it or second sourced the design... :-)
On 9/15/2016 8:43 PM, DoN. Nichols wrote:
I believe so -- but it was not I. IIRC, it was a young fellow
who was at first making the mistake of drawing arcs off carbon rods
without eye protection. Not sure what happened to him, but he was
fairly active here for a while.
I kludged together a jig to hold blades for silver soldering. It has
been improved over the years.
Two pieces of a hardwood slat. two bolts and two wing nuts make a jig
to grind an equal shallow angle on the ends.
Two pieces of scrap shallow Al chanel were fixed together, flat side to
flat side and offset. and a square hole milled in the middle and the
fence formed by the side of the upper channel, four hold down bolts
were afixed to hold the blade. If you don't use two on each side the
natural bow of the blade will give a bad weld. Two pieces of thin
approx 1/4 wide metal are used to hold the blade up so that the set of
the blade does not tilt it [the metal strips from a Peneflex hanging
file folder are fine]. This is mounted on a piece of channel. This last
is what I think makes it succesful. A 1/2 inch ferrul type Cu fitting
is fixed below the weld point. The ferrul is split to take 1/2 in
carbon rod. The end is flatened and raised level with the lower flat.
Grind you blades, place them in the jig. Carefully align on top of the
carbon rod, do not leave any gap.
Gently raise up one side and flux [I am using 50 year old]. Cut a thin
[probably 5 mil] piece of silver solder the shap of the ground surface
and place it between the ground surfaces. Take your propane torch heat
the weld until you see the solder melt, remove the flame as you press
down on the weld with another piece of carbon. This presses out any
The next is what I saw at a saw shop many years ago when they made
bades for me. I was a half round maybe 10/12" in dia. with two toggle
clamps. they put the welded blad over the half round and clampd it
down one side at a time and cleaned up the weld. Mine is just a piece
of plywood half rounded on one end with two toggles and held in a vise.
I don't do a lot with bandsaws, but what I do is some times pretty
rough. Mine seem to last.
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
Polytechforum.com is a website by engineers for engineers. It is not affiliated with any of manufacturers or vendors discussed here.
All logos and trade names are the property of their respective owners.