resistance soldering

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zotdoc
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resistance soldering

Post by zotdoc »

Anyone out there know if you can use aluminum or steel for the contacts of a resistance soldering unit? The unit I have uses copper clad arc gouging rods but the solder sticks to them and this requires frequent cleaning. I want to make a special tool to solder the ends of a 1 inch nichrome wire to 2 16 guage copper wires for fireworks ignitors and I need to make a large number of them, thus even a few moments saved by not having to clean the contacts will be significant when multiplied by a thousand or so! Thanks.
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Chris Smith
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Re: resistance soldering

Post by Chris Smith »

I would try SS based on your other combinations of metals. <p>Chemistry plays a big part here, and Aluminum might reject bonding and flow of the solder. <p>The Higher the SS number, the less cleaning you will need.
terri
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Re: resistance soldering

Post by terri »

I wonder if you could get those model rocket ignitors in bulk from Estes Industries in Penrose CO and sub them for your ignitors. Don't know the material used in the wire, but it might be more easily solderable with conventional methods. You can get a set of rocket motors from most hobby shops (the package includes the ignitors) for only a couple of bucks to test this concept. Of course, if they're nichrome, that doesn't solve the soldering problem you have.<p>I know some of the pyros around here used 1/8 W resistors of a low value (10 ohms?) with 12 v applied to them to ignite some effects. These, of course, have tinned copper leads --which are, again, easily solderable with conventional methods.<p>Both the above suggestions are for one-shot ignitors. If you are intending to re-use the ignitors (like perhaps igniting and re-igniting a gas stream, for instance) these won't work for you.<p>Have you tried spot welding? Not hard to make a small spot welder for purposes like this. I welded iridium wire to molybdenum support posts using a small custom-built spot welder on a semi-production basis a couple of decades ago. <p>The electrodes were just 1/4" copper bars with small grooves cut into them to position the two components before the welding pulse was applied.<p>[ May 21, 2005: Message edited by: terri ]</p>
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jwax
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Re: resistance soldering

Post by jwax »

Spot welding is the way to go. For a dozen, crimp them, but for hundreds, go like the production guys do- spot weld. Several hobby types are available, but building your own is possible too!
Problem with nichrome is the chrome- solder will not wet it, so at best, you end up with an "iffy" connection- totally unacceptable in pyro!
I'd like to see pics or video of your display, zotdoc! I've worked pyro at Six Flags parks, and "dabble" in pyro myself! Any "recipes" you want to share? :D
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ProboticsAmerica
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Re: resistance soldering

Post by ProboticsAmerica »

Sounds like the Spot Welders there have the best ideas, but if you do want to avoid the contact issue in other projects, American Beauty resistance soldering equipment uses carbon pliers on all of their larger units. Not sure if its the answer but it might be worth trying. FYI, Their smallest units use copper covered stainless tweezers which have exactly the same issue as you're running into now.<p>http://www.americanbeautytools.com/prod ... ?cat=plier
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jwax
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Re: resistance soldering

Post by jwax »

However you're heating the joint, you will not make a proper connection to nichrome by soldering with tin-lead. Period. Look inside your toaster, hair dryer, electric broiler. Crimped or welded.
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rshayes
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Re: resistance soldering

Post by rshayes »

Try looking on the "amateur scientist" web sites for resistance and arc welders. Here is one example (http://www.sas.org/E-Bulletin/2003-10-3 ... /body.html). There are probably others.
zotdoc
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Re: resistance soldering

Post by zotdoc »

Thanks to all. I'm going to make a spot welder and do ot that way. Jwax, all the stuff I do is consumer class, so I don't make any of the pyro stuff. I looked into it but I don't want to have to go thru all the BATF stuff. I get them from [url=http://www.bigfireworks.com,]www.bigfireworks.com,[/url] which have reasonable prices if you buy in fairly large quantities. Once I finish the project I'm going to try to post some pics!
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