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Registered Member #102
Joined: Thu Feb 09 2006, 08:15PM
Location: Raleigh, NC
Posts: 169
I usualy buy my parts form a surplus CB radio tech here. And he didnt have diodes that woudl be large enough, so SCR's were almsot as easy to use.
Heh, only reason. Though the SCR's do allow me to play around with phase modulation and such.
Well this project is actually only a side to my more major project. A self wound plate transformer for arguably one of the larger VTTC's ever. However, that will be far down the road.
Registered Member #97
Joined: Thu Feb 09 2006, 05:40PM
Location:
Posts: 61
Ok so I am building an arc welder out of 4 rewound MOTs and I was wondering a few things. First off what open circuit voltage should I be looking for? What size rods can I use? Is an HF HV arcstarter necessary or just very useful? Should I remove the shunts? Is it alright to have more turns on one transformer than on the others?
Thanks
Graham
Edit: few more questions made it a lot of questions.
Registered Member #102
Joined: Thu Feb 09 2006, 08:15PM
Location: Raleigh, NC
Posts: 169
Weee, I dont care, my project is done, I juut dropped the pilot arc idea. I was told; at my current, estabilishing an arc will not be an issue. This weekend I'm going to cut a lawnmower frame in half to get some much needed practice with this thing.
G^3 there are many things to consider. Most consumer arc welders rise to about 40VAC when unloaded. Were you to use MOT cores, you would be limited in a few ways. 1: 40V's worth of wraps might be hard to get on one MOT with any serious current handleing ability. 2 MOT's are rather easy to saturate to the point to being overly lossy.
So, with that in mind. If you're going to try to get 40V you may find putting two MOT's in serise, and then a set of those in parralell might suit you best. As far as your number of wraps goes. unless you want one MOT, or pair of MOT's doing all the work; I would defiantly not sujest having more then 1/2 wrap differnace between the 4 MOT's.
Welding rod size depends on two things: the type (and thickness) of material you're bonding to, and the number of RMS amps.
I think the final thing to consider here, is that welding works much better when your using DC. AC causes poor deposition of molten iron, but DC will have a very obvious direction of flow. (durr)
All in all, I would sujest a single transformer, with one set of high current windings. therefore paralelling secodnaries; and thus inductance, isnt an issue. Well that's about all I ahve to say.
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Carbon Arc Cutter
