So I Bought A Surface Grinder ...

The specs for the magnetic chuck and controller that came with my DoAll Grinder: input is 110v DC @ 50 watts. When I first looked over the controller and saw it used vacuum tube rectifiers, I thought uh, I'll need to replace it. I looked into replacements and indeed they all seem to put out 100-120v DC but are priced north of $300. So I cleaned it up the ancient tube unit, hooked it up and it worked perfectly! I found tubes are still available so I have no plans to replace the controller. Here are some pictures, hope it helps. IMG_8469.jpgIMG_8470.jpgIMG_8474.jpg
 
woo hoo .. learning a lot here . i powered up the magnet with a 48 volt battery charger . it works . yaaaay .

im not in any kind of hurry so i think i'll keep an eye open for a machine with a controller on it at the scrap yard before i get to carried away with it .

todays effort is going to be to get the motor mounted back on and see how the bearings sound in the arbor ... i dont for see any issues .. everything feels tight and spins easily without any noise .
 
John Hasler said:
If you ever do need to convert it to solid state you can simply plug silicon rectifiers directly into the tube sockets.
Click to expand...
Thanks for the tip!
 
If you decide not to mess with the mag controller, I have a 6x18 Brown&Sharpe permanent magnet chuck that I'll sell cheaper than what it cost to get yours going. I'm just on the other side of the state.
 
derf
why thank you for the offer , i am going to keep my eyes open for a few months before i take you up on that offer though .
i know it powers up and and i can make it work ,.. good enough for me at the moment .

i put the motor back on ,.. everything seems to be good to go ... arbor spins quiet as a church mouse with no run out .

next week im going to head to the scrap yard and see if i can come up with a one shot oiler of some type a contacter and some switches to turn it on and off with .
 
One thing to keep in mind if you hook up a simple DC power supply to the chuck. Electromagnetic chucks retain a considerable amount of residual magnetism after the power is turned off, thats why they need a demagnetizer circuit. I think it works by pulsing the magnetic field in reverse and slowly diminishing its power until the residuals are gone. Probably not too hard to build, but I suppose you could get away without it for a while...
 
Mine was missing the one shot oiler too, and I ended up using a mini grease gun with a slight modification to the piston.
 
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