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demagnetising chisel

S

Sean Boyle

Joined
Feb 22, 2012
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I recently purchased a Robert Sorby round nose chisel and have been storing it on a magnetic holder on the wall behind my lathe. I went to use it the other day and it has picked up a noticeable magnetism as it really like to stick to the tool rest making it almost unusable any suggestions on how to demagnetise it
 
any large coil or a little heat

Any large coil will both magnetize and demagnetize ferrous metal depending on which way you pass it over the coil. Also fairly low heat, long before concerns of changing the temper of the metal, will take most or all the magnetism out the metal too. If the handle comes off the chisel readily and you don't have anything else handy you might try ten minutes in the oven at 350 degrees, lightly buttered with just a sprinkle of salt. Oops! Cancel the butter and salt, wrong recipe.


Hu
 
Could you describe why it's unusable. Since I lay all my tools on the tool rest and sliding them around is quite easy even when they are magnetic It's hard for me to visualize this being a problem. I store several tools on a wall magnet and have never had a problem with them. Having been a camera repairman I own an electric demagnetizer. It's simply a coil that you put the tool into the field and it looses it's magnetizm. You can of course also magnetize with it which is really handy when you have a tiny screw that you have to install deep in the bowels of the camera.
 
Edward Weber said:
You can get an inexpensive degaussing tool primarily made for screwdrivers. Depending on the size of the gouge, it should work. Just google Magnetizing and Demagnetizing Screwdriver
Example
http://www.amazon.com/Magnetizer-De...rds=Magnetizing+and+Demagnetizing+Screwdriver
Hope this helps
Click to expand...

Those are a hoax -- but they sell well. You could use it to magnetize things, but even then it is wasted money because any old magnet can be used to do the same thing. Demagnetizing is a much more complicated problem and unrealistic to hope that a permanent magnet can be used to demagnetize anything. The BS behind the device is that you can apply a magnetizing force in the opposite field direction to demagnetize something. The problem is that without applying the precisely correct amount of magnetizing field strength, it will only result in changing the magnetization of the tool. As mentioned in a prior post a tape demagenetizer can be used with some success, but they are designed to demagnetize very low residual magnetization levels so the tool may be too magnetized for it to work. There are basically two types of demagnetizers -- one is a bulk eraser for reels of tape and the other is a wand type tool with a tip that is held close to read/record heads to remove residual magnetization.

hu lowery said:
Any large coil will both magnetize and demagnetize ferrous metal depending on which way you pass it over the coil. Also fairly low heat, long before concerns of changing the temper of the metal, will take most or all the magnetism out the metal too. If the handle comes off the chisel readily and you don't have anything else handy you might try ten minutes in the oven at 350 degrees, lightly buttered with just a sprinkle of salt. Oops! Cancel the butter and salt, wrong recipe.


Hu
Click to expand...

The first part of your answer needs a caveat -- the voltage applied to the coil needs to be AC. If DC current is passed through the coil, it becomes a magnetizing device. For most effective use, the coil should be fairly small diameter, but just large enough for the tool to pass through it and not much larger than that for best performance. I you wind your own, you will need lots of wire -- the type used to wind motors and transformers not the kind with plastic insulation. You will need enough wire to have at least a thousand turns. The electromagnet also will need to be able to produce a field strength greater than the magnetization of the tool in order to be completely effective. This means that the wire has to be sized for adequate current to achieve the desired field strength. If you follow my drift, it isn't too hard to see by now that the cost of buying or building a demagnetizer will be enough to buy a whole set of chisels plus a roll around tool chest to store them. If Sean decides to build one anyway, I can tell him how to use it -- using it incorrectly can wind up exacerbating a bad situation.

Your second suggestion is much better, but I don't know for sure that it won't affect the temper -- probably not much if at all. I have used 450° F for 30 minutes to temper O-1 steel after it has been quench hardened.

I was starting to write down your recipe. I think that it might just work if you put a nice sprinkling of Tony Chachere's Creole seasoning after the butter. I prefer to let each person do their own salt to taste.
 
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john lucas said:
Could you describe why it's unusable. Since I lay all my tools on the tool rest and sliding them around is quite easy even when they are magnetic It's hard for me to visualize this being a problem. I store several tools on a wall magnet and have never had a problem with them. Having been a camera repairman I own an electric demagnetizer. It's simply a coil that you put the tool into the field and it looses it's magnetizm. You can of course also magnetize with it which is really handy when you have a tiny screw that you have to install deep in the bowels of the camera.
Click to expand...

If you haven't had the fun of dealing with the nickel sized rare-earth super-magnets, they can put an amazing magnetization into a piece of steel. Also, not all tool rests are created equal. Some cast iron rests have a flat top that is about a half inch wide. Cast iron tool rests, being somewhat soft are very prone to become less than smooth (of course we already know that and it is the reason that Robust tool rests are so popular). Combine rough surface with magnetized tool (and magnetized rest, by the way) and there can be problems. dressing the rest with a file and then sanding up to at least 600 grit will help a lot. Putting paste wax on the rest and tool shank will make it even better.

Sean, if you check the tool rest and see if it is less than glass smooth and same goes for checking the tool shank then maybe it could be time for some maintenance work.
 
john lucas said:
Could you describe why it's unusable. Since I lay all my tools on the tool rest and sliding them around is quite easy even when they are magnetic It's hard for me to visualize this being a problem. I store several tools on a wall magnet and have never had a problem with them. Having been a camera repairman I own an electric demagnetizer. It's simply a coil that you put the tool into the field and it looses it's magnetizm. You can of course also magnetize with it which is really handy when you have a tiny screw that you have to install deep in the bowels of the camera.
Click to expand...

John.......The problems I've had with magnetized lathe tools is having metal particles stick to it while sharpening. It won't keep you from doing the sharpening, but it does interfere with your visual of the sharpening process, and they need to be removed before returning to the lathe. As you know, metal particles introduced onto your workpiece can be a source of rust later on, especially when roughing bowls with high moisture content. As with you, I don't think there is much problem with magnetism interfering with using the tool on the lathe.

I bought one of the tape demagnetizers that Rob Wallace suggested, and used it on a couple of gouges.......it works! This isn't something I'll have to resort to very often, but it's nice to be able to take care of the problem in short order. The thread linked in James Seyfried's post #2 is a good thread, and explains the use of the tape demagnetizer....... (Rob's suggestion of the tape demagnetizer, and instructions can be found on page 6, post 60, and page 7, post 65 of that thread.)

ooc
 

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Give it a hard rap

I use the small neodymium (read: STRONG) magnets around the shop, and they'll put a bit of a magnetic charge into most my screwdrivers, saws, wrenches, gouges, etc. In my experience, if the tool is 'lightly' magnetized, a sharp strike upon a hard object will demagnetize it. I do this each time I sharpen, as there are metal bits everywhere at the grinder. Here, I hit the tool upon the 2x4 supports of the grinding station. At my lathe, I'll strike the ways (I know, bad boy) near the edge at the end. It does the trick, and my Delta 46-460 has no dents or nicks. The 2x4 hasn't faired so well...
Maxwell
 
john lucas said:
Could you describe why it's unusable. Since I lay all my tools on the tool rest and sliding them around is quite easy even when they are magnetic It's hard for me to visualize this being a problem. I store several tools on a wall magnet and have never had a problem with them.
Click to expand...

John,
I hate magnetized tools. For me they don't slide freely on the tool rest they are sort of sticky on the rest and don't glide.
I just feel a resistance that should not be there. It just doesn't feel right.

We just a workshop last month and one of the students had a magnetic gouge and it was not comfortable to use.

My 2 cents
Al
 
Thanks. I just haven't noticed the problem with the few tools I have on the magnet. Maybe my magnets are too weak. Could also be that most of my tool rests are round so there's very little metal touching metal.
 
I was indeed talking AC, didn't consider DC current

The old big Forney crackerbox style welders like the CB had tons of copper in them, maybe close to a hundred pounds, monster coils. Taking the top cover off and staying away from the huge capacitor that could make you a few inches shorter if you got into it you could powerfully magnetize things. A shop owner thought this was so cool that he magnetized pretty much every hand tool in his shop! A week later the novelty had worn off and he had to be shown how to demagnetize everything except a few screwdrivers.

Wondering about magnetism but I'll start a separate thread.

Hu
 
Bill Boehme said:
Those are a hoax -- but they sell well. You could use it to magnetize things, but even then it is wasted money because any old magnet can be used to do the same thing. Demagnetizing is a much more complicated problem and unrealistic to hope that a permanent magnet can be used to demagnetize anything. The BS behind the device is that you can apply a magnetizing force in the opposite field direction to demagnetize something. The problem is that without applying the precisely correct amount of magnetizing field strength, it will only result in changing the magnetization of the tool.
Click to expand...
I wasn't trying to "hoax" anyone.
 
john lucas said:
Thanks. I just haven't noticed the problem with the few tools I have on the magnet. Maybe my magnets are too weak. Could also be that most of my tool rests are round so there's very little metal touching metal.
Click to expand...

I was thinking magnetism would not be felt as much on a Robust style rest because the hardened rod raises the tool a bit above the mass of the metal.
Any chance you have stainless steel tool rests? most stainless steels are not magnetic

If we really understood magnetism and gravity we could magnetize the tool rest with an opposite polarity from the tool which would then float over the rest. 🙂

Al
 
hockenbery said:
If we really understood magnetism and gravity we could magnetize the tool rest with an opposite polarity from the tool which would then float over the rest. 🙂

Al
Click to expand...

Al:

We would need to magnetize the tool and rest with the same polarity (North-North or South-South) so that they would repel each other providing opposing forces causing "levitation" - opposite polarity would attract, and make tool movement even harder. Additionally, at least one of the magnets would have to be adjustable to provide variable repulsive force and still be able maintain control. This same principle is already being used on some high-speed trains to "float" the train above a magnetically-inducible track to overcome friction, and also to provide propulsion for the train in the desired direction. I would suspect that there would be some serious magnetic flux densities needed (and correspondingly high current use) to be able to float our tools above such a tool rest; both would have to be fairly predictable and stable in terms of magnetic field induction (Gauss/Teslas) to be able to have enough tool control, and still be able to transfer the rotational turning forces into the tool rest when needed.

Phascinated by physics,

Rob
 
Rob Wallace said:
Al: We would need to magnetize the tool and rest with the same polarity (North-North or South-South) so that they would repel each other providing opposing forces causing "levitation" - opposite polarity would attract, and make tool movement even harder. Additionally, at least one of the magnets would have to be adjustable to provide variable repulsive force and still be able maintain control. This same principle is already being used on some high-speed trains to "float" the train above a magnetically-inducible track to overcome friction, and also to provide propulsion for the train in the desired direction. I would suspect that there would be some serious magnetic flux densities needed (and correspondingly high current use) to be able to float our tools above such a tool rest; both would have to be fairly predictable and stable in terms of magnetic field induction (Gauss/Teslas) to be able to have enough tool control, and still be able to transfer the rotational turning forces into the tool rest when needed. Phascinated by physics, Rob
Click to expand...

Of course! Opposites attract.

Read what I mean not what I write! 🙂

There are all sort if possibilities.

Al
 
Rob Wallace said:
Al:

We would need to magnetize the tool and rest with the same polarity (North-North or South-South) so that they would repel each other providing opposing forces causing "levitation" - opposite polarity would attract, and make tool movement even harder. Additionally, at least one of the magnets would have to be adjustable to provide variable repulsive force and still be able maintain control. This same principle is already being used on some high-speed trains to "float" the train above a magnetically-inducible track to overcome friction, and also to provide propulsion for the train in the desired direction. I would suspect that there would be some serious magnetic flux densities needed (and correspondingly high current use) to be able to float our tools above such a tool rest; both would have to be fairly predictable and stable in terms of magnetic field induction (Gauss/Teslas) to be able to have enough tool control, and still be able to transfer the rotational turning forces into the tool rest when needed.

Phascinated by physics,

Rob
Click to expand...

Have you considered the implications to ABC?

INSTRUCTOR: Before you begin, what is the first step?
STUDENT: Anchor the tool to the tool rest.
INSTRUCTOR: OK, do it -- right now, the tool is hovering an inch above the rest.
STUDENT: I'm trying, but it keeps popping up.
INSTRUCTOR: Here's the problem, you forgot to shift the magnetic resonance interferometer into forward drive
STUDENT: Doh!I feel so dumb for forgetting about that.
​
 
Sean, just run your chisel over the top of a Growler a couple of times or more depending on the amount of magnetism in it and you will be in business. A quick cheap fix for the trouble you are experiencing. I'm surprised some of the professionals on here didn't suggest this. Good LUCK....
 
Bill Boehme said:
What's a Growler, besides what I found in the Urban Dictionary. Surely that isn't what you mean. 😉
Click to expand...

Sorry Bill, but perhaps I should of explained what a Growler is and believe it or not that is what they are actually called.
A Growler is a test instrument used for perform various tests on an Armature. It wouldn't be worth your while to
purchase one for your own use. Check out some of the local shops that repair automotive or truck starters, they
certainly would be equipped with such an instrument which are quite often mounted to their workbench. Don't
bother with the dealers as most of them are not familiar with starter repairs, besides that it is usually more economical
to replace the entire starter with a new or rebuilt unit. Sean pay a visit to small shop that has been in operation for
a few years or visit your local community college (automotive repair dept.) and I'm sure they will be able to solve your
magnetism trouble. A Growler is really only an open frame transformer with a "V" cut in the laminations where the
armature is placed to perform the test. Hope this helps out.
 
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