"Existential Angst" wrote in message
...
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.

This mechanism seems so out of kilter, when I set the blade width knob for
1/2" (or max width), the weld time is ZERO!! Clearly DAT can't be!!

So what I did was jump out this timer contact, so that the operator can
control the weld time by holding down the weld *lever*. And boyoboy, you
sure cain't hold it down for long!! Mebbe a cupla "blips"....

I also was able to switch xsformer primaries, for a lower welding current,
since the welder is rated at 220, and I"m operating at 240. I also
"supplemented" the spring pressure with insulated channelocks, to get more
of a collapse upon heating.

I basically get two results: an instantly breakable weld, or a totally
fried blade, resulting in about 1/8" of the blade being burned away.
Typically, if the blade did weld, the flash would appear on only one side,
instead of symmetrically on both sides. And ergo a very easy break.

The annealing works fine, on the welds that do take, fragile as they are.

Many many moons ago, when I had access to a university machine shop, I
used their DoAll blade welder, very similar to mine, and it worked
flawlessly, a no-brainer. I welded dozens and dozens of blades, without
failure.

I also have a Grob blade welder, which is useless -- inneresting, but
useless -- afaict....

So am I basically too far out of my element, screwing around with these
for naught? Can I get it fixed? Is it worth getting fixed? Buy an HF
cheapie?? If I go ebay, how do I know it will work?

I also borrowed a DBW-15 (iirc), a 1" max blade welder, a big sob. There
was sumpn wrong with the alignment block, so that even tho I could finagle
a decent blade weld (nothing like the old days, tho), the g-d blade would
not be welded in a plane..... and would beat the **** out of the saw
pulleys/blade guides, and thus prematurely break.

I have some innersting stats, tho, if anyone is innerested.
Weld current seems to vary between 90 amps and 140 amps, depending on the
primary wired in. Anneal current is about 60 A. And strangely, altho the
unit is rated at 8 kV-A, the primary draw I measured was only 1 amp!!!!
Ie, really only 240 V-A, not 8,000 V-A!!! BUT, the plate does say "220
V, 30 A", which calcs out to 6,600 V-A, at least in the neighbohood of 8
kV-A. Also, the input wire is incredibly small, 16 ga *at best*, certainly
consistent with 240 V-A, so where do they get 8,000 kV-A from ??

The Grob works a bit differently, really weird, and has switchable
primaries from the front, for 3 different welding currents: about 75 A
(also used for annealing), 130 A, and 170 amps.... talk about fried
blades. But what a coccamammy system.... I'l be scrapping it, unless
someone wants it.

So does anyone have some advice?? Mebbe I should learn to silver solder
my blades?? I hear people do that effectively.
I just can't believe I've had all this bad luck, after having welded so
many blades flawlessly, back when.
Could it be cheap blades, cheap alloy??

I'm at a loss over here.
What I might do is visit some local machine shops (if there are any left,
it's been a while), and ask them to give a sucka a break, and let me try
their blade welder, if in fact they do their own blade welding.
Goodgawd.....

Appreciate any/all input.


You have to anneal the blade after welding it either by giving it a series
of short bursts further and further apart in time or by using a torch and
slowly backing it away from the blade.