Need a new rheostat for my welder, need help

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I burnt the rheostat out on my homemade portable welder which uses a B-17 bomber generator, I have no Idea what kind of rheostat to get, the old popular mechanics article states a 5.75 ohm 100 watt rheostat for the 300 amp welder and a 6 ohm 11.1 amp for the 200 amp, well I google rheostats for with these specs and all I can find on the internet is instructions on how to build this welder out of the generator ahahahahaha and yet it was so hard before when I was looking for them and searching "homemade portable welder with aircraft generator" ahahaha.Any Idea on what a suitable rheostat would be, I have no idea about this aspect of electronics.My uncle and I came to the conclusion that the rheostat was junk from sitting outside for over 30 years?  Are we right ahahaha?
Reply:What does it look like?  does it have one diameter wire wound around ceramic moon like thing or does it have three different diameters for more variation?  The guys that scrap welders probably have a decent selection.  I found one on ebay for my foot pedal which I had adapted to use one out of a scrap welder.  Then it got damaged and the places that seemed to sell that kind of rheostat didn't want to deal with folks without setting up a business account.  If it is the kind with the wire they can actually be glued back together in some cases if the wire itself isn't broken.I may be wrong but I have the impression that wire is a high chrome alloy, maybe the same stuff or close to the stuff used in resistance heaters or electric toaster type applications.  It has got to turn and a graphite kind of wiper has to be still electricly connected to a terminal and have a bit of spring force on it.  The part that holds and pressurizes the graphite puck might need repair if I interpret your post correctly.FranLast edited by fran...k.; 03-17-2012 at 02:04 PM.
Reply:Some pictures would really help herewww.georgesplasmacuttershop.comPlasma Cutter and Welder Sales and Repairs--Ebay storeTec.Mo. Dealer Consumables for the PT and IPT torch's
Reply:this is the one I was using on my welder, this particular rheostat had been sitting outside for 35 plus yearsthis is the style that was on my welder when I got it, but whilst trying to to remove the roll pin holding the knob on, I broke the shaft(get your minds out of the gutter aahahahahahahahaha)  found another one today at a friends place, his dad used to sell military surplus
Reply:I think this one might do the trick,How should I clean it? Or will it even need to be?
Reply:What is the resistance in ohms,that you need ?
Reply:I have no IDEA lol, that is what I am asking you guys lol,  Its a 28volt 200amp aircraft generator.200 amp popular mechanics welder build calls for a 6ohm 11.1amp300 amp welder build calls for a 5.75 ohm 100 watteverytime I google these specs all I get is the instructions on how to build these welders.So what can I use instead of these specific numbers?  will a 10ohm 150watt rheostat work?
Reply:Any resistance that was higher would probably work,but the range of motion would be reduced.It would probably be better to use a 5ohm and make a trimmer resistor(.75 or 1 ohm) out of a piece of nichrome wire.
Reply:That looks like a tough one to match exactly.  It appears there are two different diameter on the windings.  It also appears burnt through around the four oclock position.  Not sure how that big loose loop of wire figures in but  I put rheostat into an ebay search there are closer matches than what you found.Fran
Reply:To me it looks like a 5ohm rheostat with a larger diameter coil of wire to trim it.
Reply:In the meantime if I want to use the one in the latter picture, can I use it as is?  Or should I clean it, and if so, how do you clean it?
Reply:You might check the resistance of the old rheostat and the big coil of resistor wire.If it is close to what the new one is try it.The resistance wire will probably get pretty warm,but red hot is too hot.
Reply:I don't have anything or any access to measure it.   How does one clean the spring stype rheostat, or do I need to?
Reply:mechanic416 you wanted pics....no comments? evidentally pics have still not helped me with this thread lol
Reply:Sorry, I thought you would have an ohm meter of some sort.I suppose I would wipe it clean with some contact cleaner and run the wiper back and forth a few times.You might ask duaneb55 how to clean them.  http://weldingweb.com/member.php?u=28431He works on the miller engine dive type welders,some of which have sat outdoors for ages.
Reply:You can get one at surplus city Lincolin NE. You can use about any thing you can find. I played with diffrent ones on my welder. If I have one you can have it if you want it.
Reply:well found out the hard way why my generator is burning out rheostats, my field wire is grounding somewhere inside the generator, so I guess I get to pull it apart......................yay............not
Reply:It has got to turn and a graphite kind of wiper has to be still electricly connected to a terminal and have a bit of spring force on it.
Reply:Switched generators, managed to get the one that was sitting outside for 35 plus years flashed after trying half a dozen times, ended up running my engine whilst spinning the generator, and trying to flash it, finally worked, and WOW DOES IT EVER WELD NICE!, .  Just had the field wire hooked direct to the + terminal so was running a full 200 amps lol.  Just finished building a rheostat out of the two wrecked ons, one was burnt out and the other had the shaft broken. So I will take some pics and videos in the next few days!P.S. what a difference with the arc stabilizer!