Another electromagnetic chuck question.

[Braeden P]

Using a full bridge rectifier with a capacitor at the end will increase the voltage. so before you connect the mag chuck check to voltage I fried a few things by not doing checking the voltage.

 

[Tim9]

I have very little experience with diagrams of tube electronics. Thanks for the education Jim.

*****
thanks Braeden. I’m going to get out the V/Ohm meter today and sort this out. I know the chuck still has the specs on it so I’ll try to make sure to keep the input voltage/ current a little below specs in order to keep from burning it up.

It’s a little hard to read specs in the picture of the tag on the chuck, but it says 115v dc. I’ll shoot for 100- 105 volts dc

 

[markba633csi]

M

 

[Dabbler]

@JimDawson On my electromagnetic chuck, the circuit is more complex (it isn't tube - yay) because it incorporates demag and a few other features - I was trying to be general in case his transformer isn't centre tapped, etc. (mine isn't)

I published my circuit here for someone else that bought a chuck without the controller, but that was 5 years ago, and is now lost to time.

@Tim9 If you need it, I'll dig it out and document the controller I have.

 

[Tim9]

@JimDawson On my electromagnetic chuck, the circuit is more complex (it isn't tube - yay) because it incorporates demag and a few other features - I was trying to be general in case his transformer isn't centre tapped, etc. (mine isn't)

I published my circuit here for someone else that bought a chuck without the controller, but that was 5 years ago, and is now lost to time.

@Tim9 If you need it, I'll dig it out and document the controller I have.

I actually read a number of threads on electromagnetic chucks and I’m pretty sure I read yours Dabbler. I probably have a browser window still open with that thread, so I’m good. If push comes to shove, I can always get it working with a variac and bridge rectifiers.

 

[Eddyde]

I bought a surface grinder a few years ago, with a vacuum tube power supply for the chuck. When I got it the tubes were loose, rattling around inside the housing, I thought no way this thing will work. However, I simply put the tubes back in their sockets, powered it up and it worked perfectly!

[Grinder] - The Story Of The Grinder That Hitched A Ride With Me

Well, sort of... A few weeks ago, when I was making preparations to move my newly acquired Mill from the dealer to my newly forming machine shop, I figured I would troll Craigslist and see if there were any good deals on other machines. After all, if I was renting a truck I might as well fill...

www.hobby-machinist.com

 

[Tim9]

I will give that a try Eddy. I just figured it isn't going to work with the tubes because the wiring for the Electromagnetic chuck has been disconnected. Maybe I'll get a chance tomorrow. There's a couple of electrical enclosures with relays and some other safety stuff tapping into the three phase power feeding 120 v to the electromagnet. All of that wiring has been disconnected. Anyway my leg acted up yesterday so I was “out of commission”.
Hopefully I’m better today.

 

[Tim9]

Well Eddy it was worth a try. I connected a nice new grounded cord to the transformer. And it actually looked promising at first. One tube had a nice blue glow and my DVOM showed 65 volts dc but the other tube wasn’t even warm. So I wiggled the dead tube and boom !
I regret not having a video camera rolling because it was a very spectacular plume of smoke that followed and then two of the capacitors ignited in bright red flames.
I wasn’t fully surprised so I was ready by having the power cord plugged into an extension cord and I quickly disconnected the power cable from the extension cord at my foot.
The first picture is a before picture and the last four are after the fry job. Looks like the two things with the 3 wires are what fried. I saw an ohm reading on one before the smoke. Anyway I’m guessing that the transformer is good. At least it was. I’m guessing it still is.
Anyone have an idea what those three little tubular things are ?
I thought they were maybe capacitors and I vaguely remember reading that if you don’t want to fry some old capacitors then one should power the device up slowly. But it’s best to just replace a lot of older capacitors. Personally I would have been quite content to have gotten it working with tubes.

 

[Eddyde]

Well Eddy it was worth a try. I connected a nice new grounded cord to the transformer. And it actually looked promising at first. One tube had a nice blue glow and my DVOM showed 65 volts dc but the other tube wasn’t even warm. So I wiggled the dead tube and boom !
I regret not having a video camera rolling because it was a very spectacular plume of smoke that followed and then two of the capacitors ignited in bright red flames.
I wasn’t fully surprised so I was ready by having the power cord plugged into an extension cord and I quickly disconnected the power cable from the extension cord at my foot.
The first picture is a before picture and the last four are after the fry job. Looks like the two things with the 3 wires are what fried. I saw an ohm reading on one before the smoke. Anyway I’m guessing that the transformer is good. At least it was. I’m guessing it still is.
Anyone have an idea what those three little tubular things are ?
I thought they were maybe capacitors and I vaguely remember reading that if you don’t want to fry some old capacitors then one should power the device up slowly. But it’s best to just replace a lot of older capacitors. Personally I would have been quite content to have gotten it working with tubes.

Yikes! Sorry that happened. Those tubular parts look like wire wound resistors. They should be easy to replace. The rectifier tubes should be available as well.

 

[Tim9]

The tubes are available on EBay. Heck, I have an old TV tube service box full of tubes…..somewhere in storage. Even have an old portable tube tester. But it’s been 18 years since I was playing with tubed amplifiers. I forgot most of that limited knowledge that I had. But, the tubes are about 25.00 on EBay. And at most, I need just one.
So I’m not worried about tube availability. These #83 tubes seem to be plentiful. Interesting tube at that. They are Mercury Vapor tubes and seem to be quite durable according to what I’ve read about them.

If it’s just resistors then that wouldn’t be a problem. And Eddie, no apology needed. Like I said, I’d prefer to be able to just get it working with the tubes and maybe at a later date do a transition. FWIW, there’s even an Asian chuck control on EBay for 100.00 bucks. I’m just trying to keep costs down until I see how the grinder works.
Here’s a little info I found on the #83 tube.

Tube of the month. Type 83 tube.
I found the way they filled the tube with mercury vapor gas very interesting.