magnetic chuck controller question

[bll230]

I have an old Electro-Matic chuck controller. 115 VDC output. The momentary contact release setting is simply 115 VDC in the opposite polarity. So when I hit release all it does is fully magnetize in the opposite polarity. I don't have a manual for it. What am I missing? it is very difficult to release parts, this situation would not have been practical for a business, not being able to quickly release one part to get to work on the next part.

 

[michiganbuck]

Some /many you just bump the switch in the other direction for a short time, that bump may release.

often you pull on the part as you bump the switch.
Larger and smaller parts may take a different bump time

 

[Leg17]

Try moving switch to opposite side then quickly bringing back to 'center'.
All those I have used had a 'spring' loaded action to bring the de-mag cycle to center, or 'off'.

 

[bll230]

It is monetary contact as I mentioned above, but the voltmeter shows full voltage in release and even a bump just keeps it magnetized. Sometimes I it loosens, sometimes it doesn’t , sometimes I have to slide the part off scratching the chuck. I just don’t see how this was an acceptable product, even in the 50s. I have now read that modern controllers do a diminishing plus-minus voltage application to bring the mag power down. Maybe I can get a smart friend to design that circuit for me.

 

[michiganbuck]

Here is an old thread in chuck switches, I have not read it.

Wiring up a magnetic chuck for surface grinder

 

[CarbideBob]

You have to "bump" it say six or eight times with each bump getting shorter.

Sometimes you have to back to "on" for a few seconds and do the bump thing again.
Actually faster than most "modern" controllers once you learn to use it.
Bob

 

[michiganbuck]

Does your switch reverse the voltage?
Perhaps is wired wrong, and just the same polarity on both sides of the switch.
You might pause at the switch center, and then bump it for a half-second..and then proceed to bump a little more for the 6 or 8 times like Bob recommended.

put a voltmeter on it for each side.

 

[bll230]

It is reverse polarity in release. I am sure it is a technique thing as CB says, I'll just keep working on it.