Can you cut Rare Earth mags with a hacksaw?

[Doug Shepard]

Has anyone ever tried cutting the rod-type rare earth magnets with a hacksaw, and if so does it work? I found some info online that says you really cant grind them as the heat can destroy the magnetic field plus apparently they can catch fire too.
I've been thinking up a way to make a standoff spacer for the lower guide mounting bar on my MM16 to solve this particular issue
http://www.sawmillcreek.org/showthread.php?t=31486

What I'm contemplating is two rare earth mag rods straddling the guide bar slot and held apart by something still-to-be-determined. The whole arrangement would go between the bar and the saw frame and needs to be the same length as the factory bolt-on spacer. This would let me quickly attach or remove this standoff and force the bar to keep the same plane at all height positions. I've got to check the length of the bolt on spacer, but doubt I'll find the rare earth rods in the exact length I'll need. Dont know how hard these things are, so thought I'd ask if anyone has ever tried cutting them.

[Brian Dormer]

Interesting question....

If I recall a misspent afternoon in High School Physics class, you CAN cut a magnet in half - but they were pretty crumbly and you tended to get only one good piece out of every 2 or 3 attempts.

BTW - cutting a magnet doesnt create a mono-pole (which is only a theoretical concept), it makes two bi-polar magnets - or it would make two if you manage to not break the original magnet in the process.

I think the magnets we cut were cheap common magnets, not the rare-earth ones. The rare earth magnets I've seen seem pretty sturdy.

I also recall that the shavings from the magnet get everywhere and stick to all your tools (messy, messy, messy) - so you might want to get a cheap hacksaw and a small vise (or visegrips?) dedicated to this and try it outside.

bd

[Bryan Somers]

I may be wrong but seams like I recently saw or read rare earth magnets were made from cobalt. If thats right cobalt is some pretty tuff stuff. My instructer at school will know, I'll ask him Monday morning.

[Doug Shepard]

I may be wrong but seams like I recently saw or read rare earth magnets were made from cobalt. If thats right cobalt is some pretty tuff stuff. My instructer at school will know, I'll ask him Monday morning.

Well I was able to find the following:
Neodymium magnets are a member of the Rare Earth magnet family and are the most powerful permanent magnets in the world. They are also referred to as NdFeB magnets, or NIB, because they are composed mainly of Neodymium (Nd), Iron (Fe) and Boron (B).
Neodymium material is brittle and prone to chipping and cracking, so it does not machine well by conventional methods. Machining the magnets will generate heat, which if not carefully controlled, can demagnetize the magnet or even ignite the material which is toxic when burned. It is recommended that magnets not be machined.

Doesn't sound super encouraging, but I may give it a spin anyway to see if I can get something to work. Sounds like power machining is definitely out though.

[Joe Judge]

The rare earth magnets I picked up from Rockler broke easily.

So, maybe you can score them and break them ??

[Jim DeLaney]

Check Ebay for different sizes of magnets. They come in dozens of sizes, thicknesses, and shapes. There may be a 'stock' size that will work for you.

There are several 'stores' that sell on Ebay, so you might want to check the actual store sites as well.

BTW, I just bought forty (40) half inch diameter by one-eighth inch thick - the same size as sold by Rocklers, Lee Valley, etc. - for $20.35, including postage. That's less than half of what the woodworking catalogs are getting for them. They're gold colored, instead of silver/chrome, and are N38 (stronger) than the more common N35's.

[Boyd Gathwright]

.... Interesting thread, thanks ;).

.

[Norman Hitt]

Check Ebay for different sizes of magnets.

BTW, I just bought forty (40) half inch diameter by one-eighth inch thick - the same size as sold by Rocklers, Lee Valley, etc. - for $20.35, including postage. That's less than half of what the woodworking catalogs are getting for them. They're gold colored, instead of silver/chrome, and are N38 (stronger) than the more common N35's.

Jim, did you find those on E-bay?

[scott spencer]

I would think your hacksaw blade would stick to the magnet posing additional issues, but I've never tried it.....it'd be interesting to see how you make out.

[Jim DeLaney]

Jim, did you find those on E-bay?

Yeah, I did. Seller's id was NINTEACH. he has numerous listings for various sized magnets. Really good deal on a hundred half-inchers, among others.

Just do a search on 'neodymium' or 'magnets.'

[Doug Shepard]

Interesting question....
If I recall a misspent afternoon in High School Physics class, you CAN cut a magnet in half - but they were pretty crumbly and you tended to get only one good piece out of every 2 or 3 attempts.
...
I also recall that the shavings from the magnet get everywhere and stick to all your tools (messy, messy, messy) - so you might want to get a cheap hacksaw and a small vise (or visegrips?) dedicated to this and try it outside.
bd

I would think your hacksaw blade would stick to the magnet posing additional issues, but I've never tried it.....it'd be interesting to see how you make out.

You guys do bring up some good issues that I hadn't really thought of. When I found the online info regarding the brittleness, I thought I'd try drilling a long hole through a scrap block, putting the rod magnet through the hole and cutting through the whole block to support the cut. That may help out with the shaving problem and the hacksaw blade sticking too ??? The other thought I had later was maybe trying one of those copper pipe cutting tools that you tighten and then spin to cut through.
I might get lucky and find something just the right size but I'm not counting on it. I'd be willing to bet the Minimax bolt on spacer length is some metric length. I also want to try putting a layer of Slik-Tape across the ends if it doesn't affect the magnetic pull too badly. That's also going to muddy up the length matching a bit.
I've also got a few of the flat disc type rare earth mags from LV I may experiment with today. I think a continuous magnetic rod(s) between the saw frame and bracket is probably a better fix for what I'm trying to do. But, maybe a small wood block with disc types on either side may work out too? At least I wouldn't have to cut the mag that way. All the fitting could be done to the wood block.
I did find a pretty decent online source with a lot of different sizes - but I'll check the eBay tip too. Here's the one I found.
http://www.kjmagnetics.com/categories.asp

[Rod Upfold]

Here some info on rare earth magnets...Lee Valley site.


http://www.leevalley.com/wood/page.aspx?c=1&p=40077&cat=1,42363

[Norman Hitt]

Yeah, I did. Seller's id was NINTEACH. he has numerous listings for various sized magnets. Really good deal on a hundred half-inchers, among others.

Just do a search on 'neodymium' or 'magnets.'


Thanks, Jim.

[Russ Filtz]

Most of the small rare earth magents are plated because they're so brittle and crumbly. I've chipped a lot of them just playing around clicking them together. Don't think cutting will bring much luck.

As suggested, just do a goggle searth on rare earth and buy a pre-made size. They're made in upteen sizes/shapes.

[Doug Shepard]

I couldn't find anything the right length. I measured the spacer on the MM16 and it's 40mm (around 1-9/16"). I ended up ordering some 1/2"x1/2" and 1"x1/4" that I'll mount in a block of something that I can machine to the right thickness. I'll end up with about 13/16" between the mags on either side, but at least I wont have to cut them. I could have found something longer and tried to cut it, but realized once you start getting into the longer lengths the prices really start going up fast.