View Full Version : demagnetizers

08-15-2011, 12:38 PM
I am considering getting:


a surface type demagnetizer. Yeah, it's a import, but just can't justify a US made at 10x the price for the amount I would use it.

Do these work well?

I have a little http://www.use-enco.com/CGI/INSRIT (handheld thing) that is the most useless piece of crap. Supposed to demagnetize and it does just the opposite for every time I have tried it.

08-15-2011, 12:59 PM
If you are wanting to demag things like small wrenches and screwdrivers then all you
need is a soldering gun. Just poke the screwdriver through the loop formed by the
copper tip, while the gun is turned on, and pull it out and away about as far as you can
reach before turning off the soldering gun.

The AC field in the soldering tip reverses 120 times/second thus reversing the field on your
screwdriver. When you pull it out and away the field diminishes to close to zero while
the field is reversing. Thus no residual magnatism.

Did that make sense??

If you need to demag a bigger part, replace the soldering tip with a loop of AWG 10 copper
wire sized to suit.


08-15-2011, 01:05 PM
And he means one of these:


Not a soldering iron.

08-15-2011, 01:17 PM
If it is just wrenches and screw drivers you don't need to buy anything - just hit the metal part of the screw driver or any part of the wrench against the side of your bench vice or any metal object a couple of times.

08-15-2011, 02:13 PM
Do these work well? In general, they do. I have one by Eclipse. As for the chinese one, they'd really have to work hard to find a way to make it unusable. It's just a simple transformer with an open core.

08-15-2011, 02:20 PM
Just strip an old 110V motor down and throw away everything except the main housing and the field windings. put a 50 watt bulb in series with the wires from the field windings and a wire with a plug to plug it in and your in business. anything that will fit inside the hole where the rotor used to be will be demagnetized when it's plugged in.

08-15-2011, 02:22 PM
I am considering getting a surface type demagnetizer.

Do these work well?I can not speak to the efficacy of the product featured in the link, but I
have an Eclipse 956 Demagnetizer that is somewhat similar in form and
dates back to the late '50s. Its principal purpose was to demag ferrous items
that had spent some time on a surface grinder. It continues to work well.

Mine is older than this one, but has the same split table design



08-15-2011, 03:36 PM
I have to demagnetize all my machine tooling about twice a year and some more often. They become covered in "prickly fuzz" if I don't. Almost unusable. I don't have the name handy but it's old. Maybe from the 40s.

08-15-2011, 03:40 PM
To the OP, I have the same unit you posted. I've only used it to demag calipers, screwdrivers etc. Works well.

08-15-2011, 04:32 PM
I picked up an American-made one similar to (though newer than) the one posted by EddyCurr. I got it at the big yard sale held by Jeff of Tools4Cheap.net (last year?) and paid $5 for it. I did have to replace the busted switch, no big deal.

A new import one for $20? Why the hell not. I blow more than that on lottery tickets and get nothing for those.

08-15-2011, 04:52 PM
I have that unit from ENCO the only thing wrong with it is the switch, it should be spring off but its not. If you leave it on it will over heat, catch on fire and there goes your shop. So just take it apart and replace the switch.

08-15-2011, 06:53 PM
My Eclipse demag. does not have a spring loaded switch either. Haven't forgotten to turn it off yet. Why do you believe that leaving it on for a prolonged period would cause it to start a fire? If it overheats, I think the likely outcome would be an open in the windings and zero current flow. One could always add a fuse holder to the unit.

08-15-2011, 07:12 PM
A demagnetizer is a transformer with an open magnetic circuit. It's missing one of the pole pieces. As such, it draws maximum current all the time it is energized. If it doesn't have thermal protection this will cause it to burn out and it is very likely to catch fire before it blows the fuse. Many older units do not have any protection. The duty cycle is usually no more than 10 percent or less.

08-15-2011, 07:22 PM
With all the racket mine makes, it would be difficult to leave it on by accident. Must be a built-in safety device. :D

Geez, what's wrong with this keeyboard?

08-15-2011, 07:24 PM
Delete duplicate.

John Stevenson
08-15-2011, 07:30 PM
My Eclipse one has a button on it, might not be original as mine came out of a college.

08-18-2011, 11:33 AM
The answer to your question is that there is nothing to prevent the demagnetiser from burning out. The audible buzzer is there to remind the operator that the unit cannot be left on for constant use. The unit can only be used for 2 minutes out of every 4 to allow it to cool.

Mark Ward

Sales Manager - Magnetics and Industrial Products
442 Millen Road, Unit 9, Stoney Creek, ON, L8E 6H2
Tel 905 664 5585 Fax 905 664 7090

08-18-2011, 11:57 AM
I think I'd be inclined to use a lamp dimmer to generate the least field necessary (keeps heat low) and a timer to ensure it turns off after a reasonable interval.

In the oldy days as a student I worked for a Hamilton-Standard propeller shop in California and occasionally needed to Magnaflux parts. The degausser was a huge thing that looked like a motor case and could run all day to it had to have had a current limiter in place. I like the light bulb idea mentioned earlier as they are nearly perfect current limiters once they begin to glow.

08-18-2011, 12:46 PM
Perhaps they should just be equipped with a winding-down timer like a cheap old microwave oven has? How much money could something like that add to the cost of the unit?

08-18-2011, 01:12 PM
You could wire one of these in line with the cordset: http://www.intermatic.com/products/ec%204%20layer/in%20wall%20timers/spring%20wound%20auto%20off%20timers/ff%20spring%20wound%20commercial%20series.aspx

08-18-2011, 03:08 PM
The best way to run a demagnetizer is with a momentary on foot switch.