How to repair...

--My drafting machine finally died. One of the two tensioning bands failed at the original join point. Would silver soldering be adequate or should it be spot welded? The material is incredibly thin; maybe 1/4" wide, maybe .010" thick. I'm thinking if I heated it enough to hard solder it I might cause general annealing; not sure if that's good or bad. Anyone ever fixed one of these things??

Reply to
steamer
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adequate or

Anyone ever

We used to spot weld small stuff like that with a charged capacitor, adjusting the charge voltage to adjust the oomph. This lets you practise on a scrap bit before comitting yourself

AWEM

Reply to
Andrew Mawson

--Hey neat idea! Must go fiddle.. ;-)

Reply to
steamer

We welders are a talented group. Now, why is it that they won't let us be in the driver's seat of this nation for a year or two? We'd figure it out, get it fixed, and probably do it cheaper.

Steve

Reply to
SteveB

A friend used to have some very small silver solder, about 1/32" dia. He would cut off a very small piece, (less than an 1/8") to do delicate tasks. He would then flatten this piece with a small hammer. He cleaned the pieces to be joined, applied Silfoss flux, and then laid the tiny piece of silver solder (almost pure silver) on the joint. He would then take a small propane bottle torch and being very sensitvie heat the joint from the bottom, until the solder melted. The solder would flow into the joint... worked great.. The solder he used was much more softer than the refrigeration solder I was used to. His was, I believe, a jewelry solder. This is also a good way to mend broken band saw blades.

Reply to
pintlar

steamer wrote in news:49590974$0$1613$ snipped-for-privacy@news.sonic.net:

Ed,

What kind (make-model) of drafting machine is it? I have an old one (but no scales), sitting in my office at work, looking for a home.

Ken

Reply to
Ken Moffett

Yes. What he was using is Jewelers' Hard Silver Solder. It has a much higher silver content than most general use solders. The technique he was using is called Chip Soldering. Where you place the solder chips directly into the joint.

Jewelers' Solder comes in 3 grades, Hard, Medium, and EZ (easy flow).

If you start with Hard solder, you can do at least 3 solder actions on a single piece by using progressively softer solders.

However since every time you heat solder it burns out a few alloying elements, and therefore requires a higher temp to remelt it, you can actually get a lot more solder actions on one piece. I have known jewelers who could get 4 solderings on each grade, for 12 total solderings on one piece of jewelry.

That takes very good heat control. Traditionally Batters Flux is used, but any high temp Silver Solder flux should work.

The other trick is to boil the water out of the flux without ejecting the solder chips. Again it takes good heat control.

Reply to
Ernie Leimkuhler

--It's a Mutoh. No sweat tho; I've got the ebay replacement together and working fine.

Reply to
steamer

--Would that be the 56% stuff? I might have some in the shop..

Reply to
steamer

56% silver content is still in the repair solder category. Jewelers Solder is more like 70% - 90%.
Reply to
Ernie Leimkuhler

--Yikes! Where to get??

Reply to
steamer

I tend to get mine from Rio Grande.

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I used to buy from Swest before they were bought out.

Reply to
Todd Rich

My favorite dealer is Indian Jewelry Supply

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Rio Grande is OK too.

Reply to
Ernie Leimkuhler

Wow, Swest was big. I am surprised they got bought out.

Reply to
Ernie Leimkuhler

It was few years back, but if I remember right, they were bought out by Stuller. Which was a pain, because they wanted a business license just to talk to me. I buy my bulk silver from Hoover & Strong now.

Btw, moving the laptop out to the shop is nice. I can read newsgroups while I'm waiting for the mill to run a pass on the power feed.

Now I just need to get heat out here other than the forge...

Reply to
Todd Rich

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