Existential Angst wrote:

Awl --

I have a old DoAll DBW-1 blade welder (10465106), and for the life of me,
I can't weld 1/2" blades for my 4x6 saws.
There seems to be a fundamental problem between the spring tension that
draws the "holding jaws" together, and the timing piston that stops the
current (basedon blade width).

In the mechanism that I see, the stronger the spring tension (for a wider
blade), the *shorter* the weld time...!!
If you have taken one apart, you'll see exactly how this works.
But this seems counter-intuitive: the wider the blade, the more
collapsing
spring presure you want, AND the longer the weld time.... it would seem
to me.
I've used the Do-All welder at work, and it was amazingly good, so I never
had reason to look at the inner workings.

I managed to snag a German-made welder on eBay, the original blade clamps
had been removed and new ones jury-rigged. The blade width knob
adjusts pressure on the blade and also sets taps on the transformer for
the right weld current. The welder keeps running until the blade ends
melt together, that collapse trips a mechanism that turns off the current.
It definitely does not work as well as the Do-All model, but it makes quite
acceptable welds for the 4x6" saw. WAYYY better results that I had silver
soldering blades with a homemade jig. After some fiddling with that
jury-rigged blade clamp that came with the welder, to get the ends of
the blade to stay aligned and not slip sideways over the other end,
I now get blades that usually fail at another point other than the weld.

Jon