Magnetic blade??

[Evil D]

I meant to post this a while back and i'm just now getting to uploading pics..

But anyway the first time i reprofiled my Caly 3, during the shaping phase while hitting the edge with a coarse diamond stone, i noticed the metal powder that grinds off was collecting in a magnetic pattern on the edge of the blade. The whole section of blade up to the spine was collecting metal but this spot on the edge in particular was so magnetic it had a halo of spikey shavings formed on it..

Sorry for the crappy cell phone pics but i think you can see what i mean...





Has anyone ever seen anything like this?? Would the sharpening process have something to do with causing it to be magnetic? I haven't tried it but i don't think it's strong enough to feel it attract to another piece of metal but the shavings/powder was light enough to be effected by it.

[THG]

It happens when I use an Aligner clamp and a lot of metallic dust gets all over my stones. The blade isn't necessarily magnetic, though. I've had some blades that are magnetic and others that aren't that still do it.

If you want to demagnitize your blade, put it through the loop of the heating element on a soldering gun. It works some of the time.

[The Mentaculous]

The most logical explanation would be the constant rubbing back and forth separates the charges, creating electromagnetic potential (like when you rub a balloon on your hair and it sticks or picks up dust).

I guess there could be a magnet somewhere in the knife, but I don't see why they'd use one. They use a magnet in the Tenacious to keep the blade in the handle when closed (of course the Caly's lockback spring does that).

[Evil D]

Yeah static would make sense..

[The Mentaculous]

Yeah static would make sense..

It's really the exact same force involved in traditional magnets, so technically you're right, it is magnetic :) . The more you learn about it, the more electromagnetism freaking blows your mind...its how food fuels our bodies, it powers our lights and cars, causes our nervous system to work etc...but that's just a little bit off topic lol

[Evil D]

Yeah magnetic fields are fascinating but honestly way over my head, and i consider myself to be above average intelligence lol.

[Ben_1323]

The most logical explanation would be the constant rubbing back and forth separates the charges, creating electromagnetic potential (like when you rub a balloon on your hair and it sticks or picks up dust).

I have several knives that have very slight magnetic pulls, which I don't think are caused by static electricity because they always have this attraction (not just when they rub/cut something).

For example, my Manix 2 blade has just enough magnetic attraction to get a staple to stick, and it stays even if I turn it upside down.

Also, strangely enough, I also have a Mora knife in 12C27 stainless steel which is attracted to the Manix as well.

[The Deacon]

You can also slightly magnetize a knife by storing it near a magnet. Not enough to pick up another knife, or even a paper clip, but enough to attract its own filings which themselves would be slightly magnetic. Speakers and older TV sets with picture tubes are obvious examples of things which can do that, but there are many others. I see the effect you describe every time I sharpen my kitchen knives. Price I pay for using a magnetic knife rack. :D

[sharpguitarist]

I guess there could be a magnet somewhere in the knife, but I don't see why they'd use one. They use a magnet in the Tenacious to keep the blade in the handle when closed (of course the Caly's lockback spring does that).

:confused:
i have a tenacious and a persistance, and neither one uses a magnet for the purpose you stated. they both have a detent in the blade tang with a ball in the locking liner for closed blade retention.
some one can correct me if i'm wrong, but the only knife i know of that uses a magnet for that purpose is the t-mag.
later,
don

[The Deacon]

...correct me if i'm wrong, but the only knife i know of that uses a magnet for that purpose is the t-mag.
later,
don

T-Mag was definitely the only Spyderco knife ever to use a magnet for that, or any other purpose.

[demtek9]

Maybe it's the steel dust being removed that gets magnetized and not the blade.

[THG]

The most logical explanation would be the constant rubbing back and forth separates the charges, creating electromagnetic potential (like when you rub a balloon on your hair and it sticks or picks up dust).

I don't think that's it. Static electricity isn't produced by a knife grinding on ceramic or diamond/steel plates, and if it was, then it wouldn't be happening fast enough for this to happen. On a belt sander it's fast enough, though, and I think this is why my Delica became very magnetic when I was flat-grinding it.

And also, rubbing causes electric potential, but if I recall correctly, nothing yet to do with magnetism since there is no motion of charges.

Maybe it's the steel dust being removed that gets magnetized and not the blade.

I think this is a more likely situation. If there is a slight bit of magnetism in the steel, you're going to more likely see an effect when you have millions of small particles. Magnetism is caused by the orbiting of electrons, so when you've got millions of small pieces of metal, it's going to be easier to get them to move and align with each other. And then these particles might stick to the knife during sharpening causing the phenomenon you see.

[Johnny Boy]

You can magnetize any steel by striking it continuously in one direction. You can do it even easier when striking with a magnet. Mechanics and like minded people often do this to screwdrivers to retrieve screws and hardware that's out of reach. I don't think this is possible with non ferrous metals but your zdp-189 should be and is apparently affected.

[Evil D]

If the dust itself were magnetic, it wouldn't for the magnetic field pattern, which you may not be able to see in the bad pics but it's a circular pattern at the edge of the blade.

[Netherend]

I just stumbled on this thread after noticing that paper clips kept sticking to my Magnacut native closer to the pivot . I was not able to replicate the magnetism with Lc200n or s30v. I wonder if others had this experience with their Magnacut blades.

[pinchyfisher]

Netherend- love the scientific approach- I think the "does the paperclip stick to the blade" test is certain to become an industry standard.

I noticed when I got my AEB-L Mule awhile back that it seemed strongly magnetic, as did the Lil' Native Slipit S30V I recently bought.

Was able to validate using the paperclip test. Seems like a trend w/ Spyderco's- paperclip stuck to my BD1N- strong (Golden), S90V (Golden), M390- strong (Golden), LC200N (Golden), VG-10 (Seki), K390- weak (Seki), XHP (Taiwan), 8Cr13MoV (China). Did not stick to M4 (Seki)- so its not everything.

Paperclip also stuck to a blade w/ a butterfly in S30V and a D2 blade out of China but many non-Spyderco's did not.

By far Spyderco AEB-L, S30V and M390 were the most pronounced.

Some of these were sharpened on plated diamonds/CBN, but not all of them- so I'm guessing its a function of heat treat?

[Pokey]

Is it martensitic steel or austenitic steel?

https://www.thyssenkrupp-materials.co.u ... l-magnetic

I've noticed I can put blades near each other and sometimes they're attracted to each other.

Me, I'm generally attracted to PM 2's.