Magnetic chuck

[amateur]

I have a 110 volt surface grinder chuck that is missing the controler.Can one make there own or is it cheaper to buy one in the long run ?

[rmuell01]

I would try getting one at an auction. that's where I got my suburban.

[PeteM]

Mine is cobbled up with a bridge rectifier. Seems to work fine, though I don't have half-power etc. control.

[Bill Pace]

My 6x18 magnet is also working off one of the little, common, cheap rectifiers with a common cheap toggle switch controlling it - may be $15 cost. As said, obviously its either on or off, no fancy varying of the field and the release time is possibly a tad slower than the high dollar units -- like 4-6 secs? But for a home shop what a good inexpensive way to go.

[Evan]

It's very easy to make one. I will trade you a controller for a motor. :D

[amateur]

Good morning Evan
I'm boxing up motor as we speak :),its a .7 hp 12 volt permanent magnet.
It weighs bout 30 lbs.
Also have saem motor in .1 hp and .4 hp if you wanrt to add more,lol.
I have some rectifiers but seen a few controllers that retailer for couple hundred dollars plus with a transformer in them and wondered if just a cheap rectifier would really work.

[Herm Williams]

I made one with a full wave bridge and a dpdt switch. one way (mag on) center (off), (demag) spring loaded to off. Hold to demag position, remove demag the part as you move part from the chuck. Still works after about five years.
re

[john hawkins]

Made mine with a bridge rectifier and a rather high micro farad rating at 600 VDC. As I recall I put a .1 200 watt resistor between the bridge + and the capacitor.

[amateur]

I also had someone tell be that to de-mag it has to be switched to AC using a toggle switch etc.He claimed that by merely reversing polarity the part would still be held to the chuck.
Sound right ?

[PeteM]

Reversing polarity for a bit works for me.

[Bill Pace]

In my application using just the rectifier and a toggle, I did use a switch allowing reversal of polarity and I cannot tell any difference in release time between simply killing power and reversing polarity. I now just turn power off and wait for the few seconds - at most 5-6 - depends on size of the piece on the magnet, obviously the larger the longer the release time. A small piece will release in 2-3 sec. It just doesnt seem to justify pursuing it any further to gain a 1-2 second release.

[tdmidget]

The polarity is reversed momentarily and then off. The idea is that the part is thus repelled as it has residual magnetism of the original polarity. The reversal kills the field in the chuck. In a real controller there is an adjustment for this.