OT Demagnitize a shaft

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Model T Ford Forum: Forum 2015: OT Demagnitize a shaft
Top of pagePrevious messageNext messageBottom of page Link to this message  By Scott Owens on Tuesday, May 05, 2015 - 11:36 pm:

Hi all. My buddy has a driveshaft that is magnetize. What can be done to fix this? Thanks, Scott


Top of pagePrevious messageNext messageBottom of page Link to this message  By Frank van Ekeren (Australia) on Tuesday, May 05, 2015 - 11:46 pm:

If you don't wont to heat the crap out of it, the next best thing is to sit it on a piece of wood and hit it with a hammer, might have to repeat a couple of times in between testing it.


Top of pagePrevious messageNext messageBottom of page Link to this message  By John F. Regan on Wednesday, May 06, 2015 - 12:38 am:

If you have a device that normally is used to test motor armatures you have the greatest demagnetizer tool of all. I am speaking of a "growler". There is a cradle on top of it and it puts out a strong AC magnetic field and if you pass anything across that cradle while the cradle is under power and then pull that item away to a goodly distance while the growler is under power the whole time, the device will be dead magnetically. I mean completely dead so be careful you don't pass your credit card near it nor anything you don't want to demagnatize. I use my growler to demagnetize screwdrivers, pliers, and other tools that get magnetized by the rare earth magnets that I use here and there to hold fixturing and tooling in place. You can pick up growlers on ebay for low bucks. Pass the driveshaft along the cradle after first turning the growler on. Pass it completely over and through the thing from end to end and then move the shaft away from the growler before you turn off the growler. If you turn the power off of the growler when you have some tool in the AC magnetic field and the power disconnect happens to occur when the AC waveform is at or near a peak in the AC wave, the result will be that the item will be magnetized but if you remove the item from the field while it is under power then it will completely demagnetize the item. Magnetized tools can be a pain to work with when you don't want them magnetized.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Jim Thode Chehalis Washington on Wednesday, May 06, 2015 - 01:36 am:

Here are three methods I found on another site:

1. You can hit it with a hammer some number of times, since ordinary steel has low coercivity. Hold it at one end in a vise and hit the other end, or hold one end on a hard surface and hit the top end so that the hammer energy is transmitted though the shaft.

2. Wrap a bunch of turns of wire around the shaft to make an electromagnet. Wire a 120 watt incandescent household lamp in series with the electromagnet to limit the current. Use a household lamp dimmer to power the series combination. Slowly bring up the current using the dimmer, then slowly bring the current down to off. The more turns of wire, or the greater the load (say a 400 watt space heater) the stronger the demagnetizing field will be.

3. You can use another magnet to stroke the shaft with an opposing magnetic field.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Bud Holzschuh - Panama City, FL on Wednesday, May 06, 2015 - 09:01 am:

An ac magnetic field will do the best and easiest job of demagnetizing. John's growler or Jim's method #2 will both work.

One caveat, be sure you turn the power on to the coil or growler BEFORE you bring the shaft near, and be sure you keep the power on until you have the shaft well away (several feet) from the coil.


Top of pagePrevious messageNext messageBottom of page Link to this message  By John F. Regan on Wednesday, May 06, 2015 - 04:45 pm:

If there is a TV repairman nearby he might still have among his tools a degausing ring to restore color purity in old picture tubes. Those could be bought at Radio shack too for a time. Thuse plug directly into the wall and have a switch on them. You can then simply pass that ring all around the shaft and then move it well away from the shaft before turning it off. The ring is typically about 8" in diameter and there is no need for it to have a tight fit around anything. You can degauss about anything that you bring near it in most any direction.

I think Jim's method number 3 would be just about impossible to control since you would be far more likely to magnetize the thing more or in just the opposite polarity. Technically of course it is based on correct theory but just no practical way to implement it with the control needed.


Top of pagePrevious messageNext messageBottom of page Link to this message  By kep on Wednesday, May 06, 2015 - 05:04 pm:

Is being magnetized really a problem?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Les Schubert on Wednesday, May 06, 2015 - 06:04 pm:

I agree with Kep!!!


Top of pagePrevious messageNext messageBottom of page Link to this message  By John F. Regan on Wednesday, May 06, 2015 - 06:08 pm:

Actually I wondered that myself but figured there must be some reason they want it demagnetized.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Scott Owens on Wednesday, May 06, 2015 - 06:16 pm:

Kep and Les, If the shaft is magnetized it may attract any loose metal in the oil and there is a bearing at that end. Thank, Scott


Top of pagePrevious messageNext messageBottom of page Link to this message  By Tim Wrenn-Monroeville OH on Wednesday, May 06, 2015 - 07:36 pm:

My question is, how did it get magnetized in the first place?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Hal Schedler, Sacramento on Wednesday, May 06, 2015 - 07:49 pm:

I noted that John mentioned "Radio Shack". As I understand it, The Radio Shack stores will be gone as of May 31. As the end draws near, the liquidation prices will probably drop and there should be some good deals available...4wiw


Top of pagePrevious messageNext messageBottom of page Link to this message  By Richard Eagle Ida Fls on Thursday, May 07, 2015 - 04:30 pm:

I had followed this thread with little interest until I discovered the tapered leaf rear spring for my Touring is magnetized. I can't imagine a problem. It shouldn't transfer to the differential, but if it did it might trap shavings and keep them out of the gears. I assume it went through a salvage yard at sometime. I will use bronze shackle bushings.

Rich


Top of pagePrevious messageNext messageBottom of page Link to this message  By Richard Eagle Ida Fls on Thursday, May 07, 2015 - 04:49 pm:

I just realized how much fun I can have at car shows turning the switch to mag and then sticking a screwdriver to the rear spring.

Still causing trouble

Rich


Top of pagePrevious messageNext messageBottom of page Link to this message  By kep on Thursday, May 07, 2015 - 08:32 pm:

A magnetized sump plug might draw particles away from the shaft if you run out of options.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Les Schubert on Thursday, May 07, 2015 - 10:07 pm:

If you have a AC welding machine (typical home "buzz-box"), I would wrap one of the cables around the shaft as many turns as reasonable. Then burn a welding rod on a piece of scrap. The AC magnetic fields should do the job quickly
And NO I don't mean to weld to the drive shaft!!!!!


Top of pagePrevious messageNext messageBottom of page Link to this message  By David Dewey, N. California on Friday, May 08, 2015 - 02:46 am:

Rich,
You're a real trouble-maker!! :-)
('course, many of us here are too!)
Hey, I just realized--with such a set-up, you don't need cow magnets!!
:-)


Top of pagePrevious messageNext messageBottom of page Link to this message  By Richard Eagle Ida Fls on Friday, May 08, 2015 - 04:24 am:

Thanks David.
"When life gives you lemons, make lemonade."
I remember a Model A transmission I found at the salvage yard. The case a was OK but all the gears were magnetized. I also have a T drive shaft that is magnetized. Its an odd feeling having your wrenches stick to the parts.

Rich


Top of pagePrevious messageNext messageBottom of page Link to this message  By David Greenlees on Friday, May 08, 2015 - 07:28 am:

If there is an engine rebuilder nearby they can demagnetize it quickly in a Magnaflux machine. This is something that should be done anytime you have anything crack checked using this method.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Scott Owens on Saturday, May 09, 2015 - 04:20 pm:

Hey guys my buddy used the growler and it worked like a charm. Nothing sticks to it now. So thanks for all your help and ideas, Scott


Top of pagePrevious messageNext messageBottom of page Link to this message  By Scott Owens on Saturday, May 09, 2015 - 04:27 pm:

Hey guys my buddy used the growler and it worked like a charm. Nothing sticks to it now. So thanks for all your help and ideas, Scott


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