On 4 Jan 2008 03:42:06 GMT, "DoN. Nichols"
wrote:

On 2008-01-03, Harold and Susan Vordos wrote:

"DoN. Nichols" wrote in message
...
snip----

I think that in *that* situation -- the welder is depending on the
current through the back loop to trigger the solenoid which brings the
ends of the blade into firm contact to make the weld. I've never
bothered to actually trace out the circuitry for the stand-alone blade
welder which I have, however.

My unit is pretty primitive. The motion that brings the blade ends together
is manual, a lever that is depressed. I'm mystified by this thing, DoN.

Interesting. Mine has a solenoid which unlatches the blade
holders to slide together -- or which draws them together. I would have
to clear the space to open it up again to verify which in this case.

Unplug the unit and press the button, and the holders stay
separated. (And yes, I think that they all are rather primitive -- but
if that does the job -- who cares? :-)

All the older ones I've used are mechanical in nature.

The one we had at my previous employer was really old from the way
it was designed. On that one you set a dial to the insert position and
put the blade in. You then dialed in pressure according to the blade
width (there was a scale). It had three heat settings on another
switch. Once all was set you pulled a trigger looking switch down (it
was designed so that you pulled down and then your finger slipped
off). You then hoped it had a good weld. This particular welder took a
lot of experience to get a good weld with though it improved once I
took it apart and adjusted the switch that broke contact once the
blade holder moved. Once you had the weld you unclamped the blade and
moved the dial to the tempering position (the jaws where farther
apart) and then flipped the weld switch repeatedly till you got the
annealing temp you wanted.

That one was mounted on a DoAll saw but definitely wasn't a DoAll
design. It was much older than the saw was. The one I have now is
built into my DoAll saw and my saw is a good bit older than my
previous employers. On mine I set the blade in place and depress a
lever. The lever both turns on the current and moves the clamps
together at the same time. There is a current setting on it as well.
Once welded you move the blade to the outside of the jaws which have a
set back cut into them for the annealing witch is done with a push
button on the welder.