Make your own spot welder

Make your own spot welder

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Reply to
Jan Panteltje
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Grant does neat project videos. Have you watched his Scariac video?

Mikek

Reply to
amdx

I made one of those as a kid. IME they don't provide enough current for welding anything decent sized unless you deliberately use low contact pressure so that the resistance is much more than the bulk resistance of the steel being welded. I found this to be not very repeatable, since with only light contact pressure, the resistance (and heating) is very sensitive to the surface condition of the metal to be welded. Also I doubt it would be possible to do a second weld right next to the first weld because the second weld is partially short-circuited by the first. With a proper spot welder that can be done, because it has enough current that it does not need to rely on anything more than the bulk resistance of the steel.

Really it would be good to have at least 10kA welding current (and a lot more if you want to weld aluminum or copper). A bank of 3000F Maxwell ultracapactors (which are rated for 1900A each) seems like a reasonable way to get that, though the capacitance is so high that switching it off after the weld is necessary, and a pain since most cheap MOSFETs are rated for only about 100A. Probably a bunch of (100x) switched mode 100A constant current regulators in parallel would be useful, if they could be made compact enough. It would be quite fun to make such a cordless spot welder, but although you could get a few welds out of one charge of the capacitors, they would go flat too quickly to make it really useful as a cordless tool. I guess the ultracapacitors could be recharged slowly from some lithium cells.

Chris

Reply to
Chris Jones

On a sunny day (Wed, 3 Feb 2016 08:55:09 -0600) it happened amdx wrote in :

I have seen it now :-)

In my school days for the school party we used 2 fluorescent light tubes, cap cut of one once side, and filled with salt water. droped a piece of iron on an electric water in it to control the stage lights. move wire down for more light | \ / lights ----------------- X --------- mains | | | | | | | FL tube without cap, | | | filled with salt water | 0 | | | | | | | | | | | | | | | -|- ----------------------------- mains

Reply to
Jan Panteltje

You are correct. But you can use about 4 microvave oven transformers ( MOT ) Put two primaries in series and parallel that with the other two primaries in series and run it on 240 volts.

Dan

Reply to
dcaster

I wish someone would make a plasma cutter and stick the design up on yt.

Reply to
Cursitor Doom

On a sunny day (Thu, 4 Feb 2016 02:20:19 +1100) it happened Chris Jones wrote in :

Them little wires in them chips should work !!!!

Reply to
Jan Panteltje

On a sunny day (Wed, 3 Feb 2016 16:42:35 -0000 (UTC)) it happened Cursitor Doom wrote in :

Finnaly killed the scope?

Reply to
Jan Panteltje

Nope, it's merely back on the shelf until I can find time to test its HV transformer - something I should have done much earlier because if that's toast, the whole smps is as good as finished. I'm currently working on a mystery problem with a different scope smps...

Reply to
Cursitor Doom

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