Cutting Alnico Magnets?

[ken]

Hello...

Have any of you tried to cut Alnico magnets?

I have a pile of long stick magnets I got from somewhere, if I can cut them down I can use them.

Ken

[WolfeMacleod]

You don't. They will shatter.

[Possum]

Cut alnico yes....

Well yeah you can, you'll have to buy a lapidary diamond saw, the bad news is diamond saw blade for a small 6 inch lapidary liquid lubricating saw are expensive, the saws are expensive. The other bad news is that alnico is really hard material and trashes diamond blades real fast. I think magnet manufacturers use some kind of diamond slurry they buy by the barrel to cut the stuff. There's other ways you could do it, scoring the alnico with a carbide cut off disc in a dremel or Foredom then whack it to break it off but thats pretty crude and you'd have to grind and sand the break to make it acceptable.

I have a band saw from Micromark that will also use a diamond band saw blade with water coolant, the blade costs a hundred freaking dollars....cutting 3 or 4 bar magnets into shorter sections trashed the blade in short time.

Probably more info than you want to know eh? You could also try buying a $99 tile cutting saw at a hardware store, its likely you'll trash the blade in that thing pretty quick but the saws are liquid lubrication and designed to cut stone, I thought about it but never tried that one........Dave

[ken]

Ken

I looked at some 'Harbor Freight' tile saws, one of the cheaper ones that look like little wood saws might work. I looked at the 'big' ones too, I can't afford $400.00+ just for the saw, never mind the blade. At least I got some good ideas.

Ken

[Possum]

tile saws

I'm not sure what kind of blades the tile saws have, they might be carbide or something, but I've seen cheap ones go for $80, you could probably cut a fair amount of alnico rod with one since they're not real thick. I used to cut alot of quartz crystals, their hardness rating is 8, I think alnico is around 12 or something, its very hard material, it was difficult enough to work with quartz and quartz eats diamond grinding plates up real fast. Cheaper to have your magnets cut to size....

[ken]

An Alnico rod I use is 1/4" diameter tops... I can live with the expense of sawblades if I can get a good result. I wonder if an aluminum oxide wheel will work? When I went to HF to look at the saws, I saw some of their 'diamond sawblades', tiny pieces of diamond in the blades and not very many of them either. Maybe if I used a good quality blade, I would get more life out of them.

It's worth a try anyway,

Ken

[Possum]

cutting

1/4 inch is pretty thick, it might be smarter to score around the rod then break it and grind smooth on a cheap grinder, then sand on a disc sander. Hope this doesn't turn out to be more trouble than its worth, alnico is really hard material.....

[David King]

I can't say I've spent any time doing this but I don't think the diamond grit wears out quite so quickly, i think there is something in the alnico that must be clogging up the grit.

[mkat]

I know you're looking for ways to cut the magnets on the cheap. However, here is an extract from one site to consider:

"Alnico magnet material is very hard and brittle. On average the materials hardness is 45 Rc and conventional machine tools and cutters are not appropriate. Abrasive grinding and electrostatic discharge machines (EDM) are the typical means of fabrication for this magnet alloy. Most magnet materials are machined in the un-magnetized state. Once the fabrication and cleaning operations are complete the magnet is then magnetized to saturation."

http://www.duramag.com/magnet-materi...co/default.asp

According to the above extract, how much will it affect magnetism if the magnets are cut in a magnetised state?

Regards,

Michael

[Joe Gwinn]

How do the magnet manufacturers do it? They cannot be chewing $100 diamond blades up after four little magnets, and sell yet magnets for a buck or two.

[Joe Gwinn]

I know you're looking for ways to cut the magnets on the cheap. However, here is an extract from one site to consider:

"Alnico magnet material is very hard and brittle. On average the materials hardness is 45 Rc and conventional machine tools and cutters are not appropriate. Abrasive grinding and electrostatic discharge machines (EDM) are the typical means of fabrication for this magnet alloy. Most magnet materials are machined in the un-magnetized state. Once the fabrication and cleaning operations are complete the magnet is then magnetized to saturation."

http://www.duramag.com/magnet-materi...co/default.asp

According to the above extract, how much will it affect magnetism if the magnets are cut in a magnetised state?

Not at all, unless the magnet is heated almost to red heat. Cutting wet will keep the magnet cool. The dust from cutting may be a nuisance, as it will try to stick to the magnet or magnets.

[ken]

I've been checking on this, and it seems lots of oil coolant is used to keep the alnico cool while cutting, also very light cutting force and a high blade speed is used too. Only after cutting is the magnet charged.

Did anyone ever notice on 1960's Fender pickups the magnets have large cutting marks across the faces? They must have used a sawblade with coarse grit.

Ken

[Spence]

Why not send them to a magnet manufacturer and negotiate a price to cut them to the lengths you require.

[ken]

Well, there's a couple of reasons...

1) I asked a couple of magnet vendors to cut them for me, and they weren't interested.

2) If I can cut these with accuracy, I can do the same with mild steel rods for ceramic mag pickups.

3) I can save much $$$ by ordering whole rods, also I can cut my own unground/unpolished magnets to a length I need. Ever get magnets that varied in length in the same bag by .015 or so?

Ken

[SK66]

I've always scored the outside with a dremel and reinforced cutoff disk then grind them. I will also demagnetize them and remagnetize them. I use a large tool demagnetizer to demagnetize and Neo Bars to remagnetize. If you need to make many the exact same length you can get a piece of steel plate drilled and then hardened, leave in full hardened state. The you put the rod(s) in the hole(s) and apply to a sanding disk until the steel hits. The large face of the steel plate will prevent from ginding too far and help keep things cool and holdable. You can do this without first demagnetizing, but remagnetizing might be a good idea.