Recent content by Ricka

Skeptic2: Thank you for your interest. The SCR's in the diagram are rated at 90a and I don't exceed about 60a (I only need this current control for TIG welding on thin stuff) and on a low duty cycle, so I would't think I'd overheat them. But assuming I stay within the design limits of the...

I wonder if I can get some opinions on this circuit before I go looking for the parts. It seems simple enough even I can build it. Alternatively, does anyone have any dope on making a saturale core reactor (magnetic amplifier) to control an AC welder? All I can find on the web is theory. As...

I once saw a 90* motion transfer mechanism that had been used in lineshaft systems. It's input shaft drove a reciprocating arm via a ball joint which, in turn, caused a central shaft to oscillate. This oscillating motion was imparted to a second reciprocating arm which drove the output shaft...

Jim: Been awhile, but I finally solved my problem. A guy was giving away a couple of mobility scooters on CL and I took the 24v DC motor out of one and powered it with a rewound MOT and couple of 35 amp bridge rectifiers in parallel and an old treadmill choke. It seems to work fine, but I...

Yeah, I can't believe the starter was made with three brushes; I'd guess someone removed it, but who would go to the trouble of drilling out rivets, rather than just leave out the brush? I separated the fields from the brushes as he described but haven't got the motor to run that way, with...

A lawnmower battery crossed my mind, being small but holding enough charge to run a starter. Of course, I'd have to BUY it, which I always try to avoid! I think I have a mower starter kicking around, too. Today I was rewiring my starter to run in reverse IAW this...

Jim: Don 't assume I know more than you! All I know about things like this is what I've learned on the web (like all Will Rogers knew was what he read in the papers). I used a MOT to make the choke for the DC conversion of my welder. I used bare copper cable and wrapped electric tape...

Thank you, Jim; wouldn't have thought of that. I also got to thinking how big the transformer is in a good sized battery charger and it would seem that one that would power a starter motor would have to be bigger yet, much bigger than a MOT. Maybe it wouldn't get too hot during the short...

Old Jim: Could you also answer another question? I've been looking on E-bay for a rectifier big enough to run this starter motor, and most of the bigger ones are three phase. The internal wiring looks similar; do you know if one would work with single phase? Thanks. Rick A

You can make a spot welder out of one: http://www.5bears.com/welder.htm I looked for the website that told me how to make the soldering gun, but no luck. I used a piece of 1/4" carbon arc gouging rod- it's cheap at a welding supply store. I just extended the small middle winding, put an...

Yeah, even these treadmill motors will give a pretty good twist; I clamp them in the vise. Wasn't aware of the idea of resistances on the rectifiers. I'd read about the problem of unequal load sharing but haven't observed any problem with my welder yet. I've fooled with MOTS enough to...

Jim: That sounds like a logical explanation for my problem- asking too much of the motor. In theory, you'd think lifting the table on a 9" X 42" mill at the rate I do wouldn't tax a motor like that. Before I tried the treadmill motor, I had a .5 hp AC wash machine motor, which lifted the...

Jim: Yeah, I can do that; have a clamp on meter. Although, don't know if the classic hp formula applies to a treadmill motor- they seem to rate them HIGHLY optimistically! Rick A

Jim: Yeah, they turn at about 6600 rpm. Knowing that, I built a worm and pinion reduction gearbox, plus there's about a 3:1 reduction from the treadmill belt and pulleys. It worked well until the first motor fried. It turned the handcrank a lot faster than I could by hand. It takes 240...

Didn't get a chance to do more than spin the motor with a drill today, but it put out current as predicted. I'd think the welder open curcuit voltage wouldn't matter, it's still below the motor's rating. Hope to try that tomorrow. Thanks. Rick A