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
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 shit 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*
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.
Appreciate any/all input.