Blade-welding blues....

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 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*, 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.
--
EA




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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.
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Annealing is fine.... it's the weld that's disastrous.
But Sam, you don't have any saws, right? So you don't use a blade welder, eh?? :) :)
--
EA


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Admittedly, I haven't welded one in many many years now...I buy them pre-welded either from Saw Service or off ebay..
I have a DoAll C58..
http://www.equipmatching.com/uploads/images/ibj14jg4ac.jpg
--takes 144 x 1 blades and I use 3-4 pitch which minimizes clogging beings as generally I stack bars for an 8in wide minimum cut.
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On Wed, 5 Dec 2012 23:16:21 -0500, "Existential Angst"

I have (4) blade welders. All of them are old. And all of them do pretty much as yours do. I took one to a guy who actually repairs them..and he told me it was frankly..worn out. My DoAll is good for up t 5/8" stock and it may weld..but the welds are so poor that even decent annealing wont save them. They Will break. Sometimes putting them on the saw..sometimes within the first dozen cuts.
So now I heliarc them with the TIG. That was a learning experince....shrug
Ive heard the Harbor Freight welder works well enough. Id suggest buying one and trying it. Or find a shop close by that will let you knock off a half dozen or dozen blades on their machine.
And only..only buy Lennox bi-metal blades. Chinese blades suck and the Starret arent much better.
Gunner
The methodology of the left has always been:
1. Lie 2. Repeat the lie as many times as possible 3. Have as many people repeat the lie as often as possible 4. Eventually, the uninformed believe the lie 5. The lie will then be made into some form oflaw 6. Then everyone must conform to the lie
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wrote:

Indeed, very unimpressed with Starrett.... Inneresting you've had similar experience.... I too have a feeling that this thing is just "worn out". I've heard silver soldering does a very good job, once you get the technique down.
Can't find the HF blade welder!!
--
EA



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On Thu, 6 Dec 2012 01:53:20 -0500, "Existential Angst"

Silver soldering does indeed work, and very well.
Simply grind a taper on the inside of each end, put a bit of GOOD silver solder between them and heat with a torch.
http://weldingweb.com/showthread.php?t03
Lots more on the web.
I couldnt find the welder at HF either
http://www.use-enco.com/CGI/INLMPI?PMPANO 33808&PMKBNO10&PMPAGE
The methodology of the left has always been:
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I would like the Grob blade welder. I have a Kalamazoo but off saw that could stand a new blade. And would like to try to reserect the Grob blade welder. I get up near you every once in a while. My son lives in Peekskill.
Silver soldering blades is not too hard. Flip one end of the material and clamp it to the other end so you can grind a taper on both ends at the same time. Then clamp the ends so the ground parts are against eath other. Use plenty of flux. Some sort of jig to hold the blades while silver soldering is good. I made one from a short piece of angle iron. Milling a bit away so as to have a straight edge to align the blades, And milling away some material so the ends being soldered do not have any of the jig sucking up the heat.
Dan

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I would like the Grob blade welder. I have a Kalamazoo but off saw that could stand a new blade. And would like to try to reserect the Grob blade welder. I get up near you every once in a while. My son lives in Peekskill. ==================================================== Peekskill is nice, an overall scenic area, Bear Mountain bridge, etc. iirc, they landmarked some old, old small factory buildings somewhere around the park, really interesting. It's been a while since I've explored around there.
At its working best, I don't think this welder could handle over 3/4", and the clamp itself seems to be for a 1/2" blade, with no alignment stop in the back -- kinda odd. The face plate is bent, the grinding motor frozen, wheel-less -- seen better days, f'sure. But the main stuff works.
This fellow made his own blade welder: very impressive:
http://www.youtube.com/watch?v=X6c0qlDghEs

Not sure if it's really that easy to make and "get right", or if he just lucked out with the right xsformer/current, etc.
So, yeah, you can come by, pick it up, but it's not a freebie: I'm going to hand you a testimonial to my character, very good looks, and superlative shop skills, that you'll have to post on these here ngs on a regular basis.....
Silver soldering blades is not too hard. Flip one end of the material and clamp it to the other end so you can grind a taper on both ends at the same time. Then clamp the ends so the ground parts are against eath other. Use plenty of flux. Some sort of jig to hold the blades while silver soldering is good. I made one from a short piece of angle iron. Milling a bit away so as to have a straight edge to align the blades, And milling away some material so the ends being soldered do not have any of the jig sucking up the heat. ============================================================ Yeah, I'm going to have to practice some.... lord knows I have enough blades.... lol I would mebbe just heat the fixture from underneath, before heating the blade itself, toward the end of more uniform heat to the blade. Right now, tho, I'm just despondent.... lol
--
EA


Dan




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Existential Angst wrote:

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
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