Demagnetize a lathe tool......?

[Odie]

I'm noticing fine grinding particles stick to a few of my HSS lathe tools while grinding, and assume a few of them may have become magnetized.

One of the machinists at work said to strike the shaft on a hard surface, but I'm not willing to do that, at this point.

There are electric demagnetizers that I know of, but wondering if there is any way to eliminate this without expense.......?

ooc

 

[MichaelMouse]

Stroke with a magnet. Or buy one of the devices like this if it bothers you. http://www.restockit.com/search.aspx?sid=12E62A5F563B&Ntt=magnetizer&N=0

 

[Harry Robinette]

RE Demag.tools

Odie
I use a hand demagnetizer from Woodcaft works great cost about $8.00 if I
remember right.I use magnetic strips to hold my tools and it leaves just enough
magnetizem to cause the tools to drag on the tool rest I use this demagnetizer and all the drag is gone.Works good.
I believe it works on tools up to 5/8 or3/4 round.
Harry
Ps just saw Michael's post thats what I use there cheaper at that web site the Woodcraft

 

[Odie]

Stroke with a magnet. Or buy one of the devices like this if it bothers you. http://www.restockit.com/search.aspx?sid=12E62A5F563B&Ntt=magnetizer&N=0

Odie
I use a hand demagnetizer from Woodcaft works great cost about $8.00 if I
remember right.I use magnetic strips to hold my tools and it leaves just enough
magnetizem to cause the tools to drag on the tool rest I use this demagnetizer and all the drag is gone.Works good.
I believe it works on tools up to 5/8 or3/4 round.
Harry
Ps just saw Michael's post thats what I use there cheaper at that web site the Woodcraft

OK, thanks MM and Harry........

I see the Woodcraft version is $4.99 right now, so I put it on my wish list there.....will get one on my next order. I haven't noticed any drag on the tool rest, but it would make sense to eliminate it for that reason. The real reason I would like to eliminate the magnetism is for visual inspection purposes while grinding and honing the edge......not having those clinging metal particles would make things a little easier to see, that's all.

Thanks, ooc

 

[James E Gaydos]

demag

Hi Odie,
That hard surface could be a piece of wood. I also noticed this when I was working as a production turner. I used to slam my gouge or skew or what ever tool, down on a moving blanket that was on top of my work cart. Works every time. Not a permanent solution, but it works.
Jim

 

[Odie]

Hi Odie,
That hard surface could be a piece of wood. I also noticed this when I was working as a production turner. I used to slam my gouge or skew or what ever tool, down on a moving blanket that was on top of my work cart. Works every time. Not a permanent solution, but it works.
Jim

OK, thanks for the additional input, James.......

I had thought striking on a steel surface is what was meant, and I really didn't want to bang on my good lathe tools!.......but, I'm going to try some other things, like a block of wood. A temporary fix would suit the need just fine. If it works, I may just duct tape a scrap piece of wood to the grinder pedestal column for this purpose.......

ooc

 

[MichaelMouse]

Way magnetism works, you probably wouldn't detect any "drag" on the rest unless you were checking with the very end of the tool. Remember those iron filing lines from middle school? I can pick up perhaps three-four 1/2" brads with the end of my gouge which has been hanging by a magnet for fifteen years, but cover the first inch and nothing sticks.

 

[Gretch Flo]

Magnetism

Thanks for the post, Odie-I have one Ellsworth tool that was magnetized from the get go-must not have been demagnetized in the machining . It is irritating some times when I am making fine cuts and it "slams" onto the tool rest. Lyle Jamieson noticed it when it was new and I was at one of his hands on courses.May have more magnetism than what you all are saying. Will try the slamming trick, and then buy one on my next woodcraft order if that simple doesn't "work". ( have 5 Ellsworth gouges used at the same time (several of them were when they were "spent" using a sorby fingernail grind jig, and then I bought a wolverine and got 1 more inch out of the old dead ones-knew I saved them for a reason). It's #3 when I sharpen. Gretch

 

[Odie]

Thanks for the post, Odie-I have one Ellsworth tool that was magnetized from the get go-must not have been demagnetized in the machining . It is irritating some times when I am making fine cuts and it "slams" onto the tool rest. Lyle Jamieson noticed it when it was new and I was at one of his hands on courses.May have more magnetism than what you all are saying. Will try the slamming trick, and then buy one on my next woodcraft order if that simple doesn't "work". ( have 5 Ellsworth gouges used at the same time (several of them were when they were "spent" using a sorby fingernail grind jig, and then I bought a wolverine and got 1 more inch out of the old dead ones-knew I saved them for a reason). It's #3 when I sharpen. Gretch

you bet, Gretch........

Magnetized lathe tools is a subject I don't recall being discussed before. I produced one small bowl yesterday, and made it a point to watch for magnetized gouge......but, didn't find one! The gouge that inspired this thread must be one of the other gouges I have.......

Comment on your Wolverine: Just wondering at what distance you've set the length of protrusion for gouges in your Vari-grind jig......? I'm posting from memory here, and I believe the minimum distance is 1 1/4". Whatever that number is, it is what I have gone with. This way, I'll always be getting the maximum use out of gouges before they are too short for the Vari-grind jig. At this minimum distance, I've run the jig into the corner of the grind wheel quite a bit at first, but now that seems to have abated some......I guess there will be no further grinding on the jig itself, and since the Wolverine is built very thick and sturdy, I don't foresee any problem with that.....

ooc

 

[Bill Boehme]

Stroking a piece of steel with a magnet is a technique for magnetizing it.

The machinist was correct about striking it to help demagnetize it. It needs to be a really high impulse strike, so lay it across an anvil and whale the heck out of it with a medium size hammer. Be advised that once magnetized, there will always be some residual magnetism.

Another technique is to anneal the steel and then temper it to the desired degree of hardness. However, this will not work with powdered metal steel.

The way that I would demagnetize it is to use an old filament transformer (bet you can't guess what a filament transformer does) and wind a large coil about six inches diameter and about a hundred turns or so of Formvar insulated wire (the stuff used to wind motors and transformers). Turn the power on and very slowly bring the tool towards the coil and pass it through the loop and then very slowly move the tool away from the loop until it is about three feet away before turning the power off. This procedure may need to be repeated numerous times to reduce the residual magnetism to near zero.

Finally, why the heck are you worried about a magnetized turning tool anyway?

 

[n7bsn]

....
The way that I would demagnetize it is to use an old filament transformer (bet you can't guess what a filament transformer does)

Wanta bet? (I traded my tube tester to another turner for wood)

Finally, why the heck are you worried about a magnetized turning tool anyway?

I certainly don't, my thin parting tool is stored on a strip, and is getting fairly magnetized. Doesn't effect it's cutting

 

[john lucas]

I have several tools that are magnetized. I never noticed it being a problem. Bill is correct about the wire field method of demagnetizing. I have one of the devices that I bought when doing Camera Repair. Sometimes you really need a magnetic screwdriver and sometimes it's a real nuisance. We would place the screwdriver in the field of the coil and turn off the unit. That would magnetize them. If you insert it into the field and pull it out about 3 feet before turning off the unit it would demagnetize it.

 

[Bill Boehme]

Wanta bet? (I traded my tube tester to another turner for wood)

Well, actually, I knew that my comment would draw you (and possibly other hams) out of the woodwork.

At one time, I had a huge supply of filament, power, audio, RF, IF, isolation, and flyback transformers. Since filaments have become an endangered species, I no longer transform them. Instead, I just push "dopey" holes and electrons around.

I certainly don't, my thin parting tool is stored on a strip, and is getting fairly magnetized. Doesn't effect it's cutting

I have a bunch of nickel size supermagnets that I use for holding tools. I have not used them yet for holding turning tools except for a parting tool, but have experimented to see how well they would work for this use.

 

[Mark Warden]

I made a rack for my chisels that attachés to the back of the bed with 2 of these. http://www.kjmagnetics.com/proddetail.asp?prod=BY0X08
Every now and then I hit 1 of the magnets while trying to put chisels back in and the only way to get them off is to slide it off the end of the magnet. This magnetizes them to the point that you can definitely feel drag on the tool rest. I use a bulk tape eraser machine and it totally demagnetizes them. So if your having magnetism problems you can't fix you pay shipping both ways and I'll demagnetize it for ya.

 

[Gretch Flo]

Magnetized gouge

Finally, why the heck are you worried about a magnetized turning tool anyway?

I used #3 yesterday . When it gets 1 1/4-1 1/2" from the rest it "clunks down"/ . I tried wackong it on a piece of woof, and then a steel burnisher.-not reeeeal hard-no effect. Occasionally I have the tool rest right next to the wood, and once (long time ago I think), I think I made an uncontrolled cut. at first. Another time I was cutting at the back of the blank .near the chuck, , truing up the eventual face so I could determine the outside curve. The chuck lured it, but with lightening like reflexes I didn't get it knicked by the chuck.. (or vica versa) It's just irritating that's all. Gretch

 

[Bill Boehme]

I used #3 yesterday . When it gets 1 1/4-1 1/2" from the rest it "clunks down"/ . I tried wackong it on a piece of woof, and then a steel burnisher.-not reeeeal hard-no effect. Occasionally I have the tool rest right next to the wood, and once (long time ago I think), I think I made an uncontrolled cut. at first. Another time I was cutting at the back of the blank .near the chuck, , truing up the eventual face so I could determine the outside curve. The chuck lured it, but with lightening like reflexes I didn't get it knicked by the chuck.. (or vica versa) It's just irritating that's all. Gretch

That is a pretty impressive magnetization -- almost supermagnet quality. I am wondering how it became so strongly magnetized in the first place. I think that your tool would need to be electrically demagnetized. While mechanical shock might help it probably won't be very effective. If the steel happens to be a type that has a high intrinsic coercivity (meaning basically hard to demagnetize) then it may always have some residual magnetism.

Maybe this is actually a good feature -- an automatic mechanism for the first step of the three step ABC turning rule (anchor).

By the way, the mechanical shock that was mentioned earlier needs to be far greater than tapping the tool with a piece of wood or a burnisher. Think in terms of a 2-lb. blacksmith hammer. Lay the tool on the blacksmith's anvil and then hit it with the hammer using a full windup swing as hard as a blacksmith would be able to deliver. If the tool does not break or bend, it might be demagnetized after about fifty or so of these "taps".

 

[Odie]

Finally, why the heck are you worried about a magnetized turning tool anyway?

Only reason for me is to see the sharpened and honed edge of the tool closely and clearly.......without the steel particles clinging to the tool.

Magnetized lathe tools really hasn't been much of a problem for me, but I saw it within the last week, or so......It's not a constant problem. There is a gouge in my "arsenal" somewhere that is magnetized, but I didn't see it when I was turning on Saturday.

Next time I happen to sharpen the offending tool, I plan on whacking it on a piece of wood. If that doesn't demagnetize the tool, it still may be satisfactory if the steel particles are bumped off with the hit........we'll see.

In any case, I will not be whacking any of my tools on steel.......I can only imagine dents on the shank resulting from that.

ooc

 

[Odie]

I used #3 yesterday . When it gets 1 1/4-1 1/2" from the rest it "clunks down"/ . I tried wackong it on a piece of woof, and then a steel burnisher.-not reeeeal hard-no effect. Occasionally I have the tool rest right next to the wood, and once (long time ago I think), I think I made an uncontrolled cut. at first. Another time I was cutting at the back of the blank .near the chuck, , truing up the eventual face so I could determine the outside curve. The chuck lured it, but with lightening like reflexes I didn't get it knicked by the chuck.. (or vica versa) It's just irritating that's all. Gretch

Now....THAT......is more than just irritating........it's definitely a safety concern, Gretch.......

Glad you caught things in time!

A lathe tool that is magnetized to such a degree should be demagnetized for sure........

ooc

 

[Harry Robinette]

demag by whacking

I use mostly D.Thompson tools, Whacking them on wood or metal or anything is a BAD idea.Use a demag. it's only $4.99. I'm pretty sure any manufacturing company will tell you not to WHACK your turning tools on anything.
Just MHO
Harry

 

[n7bsn]

I use mostly D.Thompson tools, Whacking them on wood or metal or anything is a BAD idea.Use a demag. it's only $4.99. I'm pretty sure any manufacturing company will tell you not to WHACK your turning tools on anything.
Just MHO
Harry

The Harbor Freight one is $3.99

(Harbor Frieght, your source for cheap, disposable tools)

 

[MichaelMouse]

You can still use the method of stroking N-S with a magnet oriented E-W. Spinning a bar magnet from a string over the tool or vice-versa will do, or turning it round and round over the windings of a motor that's running.

I still have never seen any of my tools which live on magnetic bars (admittedly running E-W) gather enough to bother with, especially anywhere behind the absolute end. Strength of the attraction depends on curve of the field, right?

 

[Bill Boehme]

The Harbor Freight one is $3.99

(Harbor Frieght, your source for cheap, disposable tools)

Those permanent magnet widgets that supposedly magnetize and demagnetize tools are mostly a joke. The advertising is misleading because it implies that it can impart a magnetic "charge". Since there is no such thing as a magnetic monopole, there is no such thing as a magnetic charge as the advertising states. This trinket can be used to slightly magnetize a screwdriver or screws which can be useful when working with tiny screws in tight places, but is essentially useless for demagnetizing tools. The reason that this device is not effective in demagnetizing is that it would need to be able to produce a greater coercive force than that used to magnetize the tool. In addition, unless one also knows the polarity of the magnetized tool, a permanent magnet such as this would not be very effective.

 

[Dale Miner]

Not only would the coercive force of a permanent magnet need to be strong enough to eliminate the magnetism in the piece, it would have to be just strong enough, or it would reintroduce a magnetic field in the oppostite direction. A strong diminishing AC field is the best way to demagnatize. Next best is a reversing DC field with incremental drops in the field strength (current).

If one has a soldering gun (the pistol looking type), take the tip out, make a coil of 12 or 10 gauge wire with about 15 to 20 turns large enough to pass the tool through and connect it where the soldering tip would ordinarily go. Pull the trigger, pass the tool in one side of the coil, through the coil, and out the other side until the tool is a couple of feet away, release the trigger. The coil will get hot. Increasing the distance between the coil and the tool is the diminishing field part of the formula.

 

[Odie]

Was working on a "Japanese style" bowl this evening, and found the gouge that has some magnetism. As I ground the edge, those pesky little pieces of metal dust were clinging to the gouge. Tried whacking the gouge on a block of wood........didn't do anything to eliminate the magnetism, but it cleared the gouge of the metal particles.........success!

The magnetism in this particular gouge is fairly weak, so eliminating it isn't that much of a priority.......getting the metal dust off the edge was the whole point!

Thanks to all for the help........sometimes solutions come unexpectedly! :cool2:

ooc

 

[Bill Boehme]

You can still use the method of stroking N-S with a magnet oriented E-W.

If I understand what you are saying, I can't see how this would be effective. Also, consider that the tool is a magnet too -- so which one becomes demagnetized ... and, why? Do they demagnetize each other? Or, perhaps further magnetize each other? The right answer is neither. See my earlier post and the one by Dale Miner.

Spinning a bar magnet from a string over the tool or vice-versa will do, ...

Well, if it were on a string, it would not spin -- the magnet would simply pull towards the steel tool like a compass needle pointing towards the magnetic north pole.

... or turning it round and round over the windings of a motor that's running.

That won't work either as there is very little flux leakage outside the motor. If that were not the case, the efficiency of a motor would be reduced by the lost energy. The magnetic field is almost entirely contained within the iron laminations except at the magnetic gap between the field and rotor. The gap distance is only a few hundredths of an inch so the flux density outside the gap region is quite small. Additionally, even if there were any stray magnetic field, the steel housing of the motor is a very effective magnetic shield. Reducing any stray magnetic field within a motor is important for more reasons than efficiency -- stray fields would induce currents in the ball bearings at each end of the rotor and result in rapid deterioration due to pitting caused by ion migration.

I still have never seen any of my tools which live on magnetic bars (admittedly running E-W) gather enough to bother with, especially anywhere behind the absolute end.

I have not found a problem either. The reason that the tip of the tool is where magnetic attraction takes place is that the field is contained entirely within the bar except at the ends.

Strength of the attraction depends on curve of the field, right?

I am not clear about what you are saying. Would there be a possibility that you are confusing it with "curl"? Curl is a vector calculus operator used to calculate magnetic field strength, but has nothing to do with curvature. Flux density is the the term that gives the strength of a magnetic field at a given point.

 

[MichaelMouse]

Alternative methods for inducing competing lines of magnetic force to randomize particles and therefore demagnetize. Simple as that, done thousands of times a day in earth science demonstrations in schools everywhere.

Perhaps you remember back in school where you learned that the lines of force could be revealed by filings? Then learned that where the lines of force were curved the most, the most attraction was present? On a bar magnet like a lathe tool, if you get any distance behind the nose where the lines of force are parallel to the body of the tool attraction is nearly nil. Once again, an old elementary and middle school standard demonstration.

I make no claim, nor have I, that it is the most efficient way to do things, merely that it will do them, if, for peace of mind or perceived resistance you would like to.