Now that the cheapest Capacitive Discharge welder on the market is priced at about $2,500, I figured it is time to build another home-brewed CD welder. 

 I built one about 15 years ago, using about 3 Farads worth of high grade 220,000mfd / 25 Volt (or maybe 40V ?  I don't remember for certain) surplus mainframe computer supply capacitors.  I got them at a great scrap yard in Phoenix ; Davis Salvage for about two dollars each.  Try THAT today. 
The cheapest I could find  on eBay recently were like 25 dollars each.. Plus $6.00 shipping each..

The one I built 'way back then' weighed about 85 pounds and didn't work as well as I wanted it to; mostly due to poor electrical engineering and materials choices.

Well, I'm not much better at engineering, and far away from any good salvage and surplus shops, but I HAVE learned a few things, and managed to find all the parts I need at the local Walmart, Radio Shack, and Ace Hardware stores in my little 'Podunk' town, and from eBay.

 


This first 'episode' will show you how to build your own very 'bare bones', but effective, Capacitive Discharge welder for about $100.00.  Much less if you are a good scrounger or packrat and maybe a little more if you don't shop around for the best deals.  In later installments, I'll show some improvements on components, engineering and maybe even aesthetics. 

 


The key ingredient is a powerful capacitor.  The minimum I'd recommend is 1(real) Farad.  3F or more would be much better, I think.
Now that good surplus electronics power supply grade capacitors are rare and expensive,  we are fortunate that 'stiffening' capacitors used in car stereo systems are getting cheaper and widely available.
I got a 1.5 Farad cap off eBay for about 40 dollars including shipping. 

  
(Most photos can be clicked on for a larger view)

You have to be kind of careful about buying these capacitors;  There is a LOT of exaggeration of the specifications by the sellers and manufacturers.  I don't have a way to measure it, but I think this one is closer to 1F than 1.5F.  And the supposed '3 Farad' one I got a couple of days ago wasn't even half the power of the 1.5 F above. (HINT: stay away from the Pyramid brand of capacitors.)  The 1.5F in this description is a Volfenhag brand.

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