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Cutting cobalts


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#1 chasbeeman

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Posted 24 February 2017 - 12:22 PM

I'm needing to shorten some .445" long magnets to about .250". Any advice would be greatly appreciated since I'm reluctant to fire up the Dremel and hacking away.

Didn't want to ruin these magnets but I'm sure that they can be cut shorter with care.

Thanks in advance to the pro cobalt cutters out there!


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#2 MSwiss

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Posted 24 February 2017 - 12:33 PM

Advice.

Don't do it.

I'm still in counseling over doing it... and owning both a Fiat X1/9 and a Lancia Beta Coupe 35 years ago.

If you don't follow my advice, at least get a diamond cutting disc for your Dremel and expect about a 50-50 chance of achieving mediocre results.


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Mike Swiss
 
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#3 gotboostedvr6

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Posted 24 February 2017 - 01:04 PM

They crack very very easily.

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#4 zipper

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Posted 24 February 2017 - 01:05 PM

Yep. A diamond wheel is a must - done it. A dentist's separating disk to be precise, with diamond layer on the edge. A mess...


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#5 John Streisguth

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Posted 24 February 2017 - 03:07 PM

Samarium cobalt material is pyrophoric, which means the dust can possibly self-ignite. You need to do the cutting in water. I've been involved with the manufacture of all types of hig-tech magents over the last 30 years, and I can't stress enough this is not a good idea.


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"Whatever..."

#6 MSwiss

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Posted 24 February 2017 - 03:34 PM

I don't dispute any of the above.

 

But for one pair, I doubt you would need to worry, especially considering, at Koford, the slightly bigger volume I did by hand, for multi-mag set-ups.and the large volume, we did, on a surface grinder, for single mags, before we got EDM machines, and you never heard of "The Great Koford Fire of 87."

 

Regardless, I talked to Chas by phone, and I don't think he is going to try.


Mike Swiss
 
IRRA® Components Committee Chairman
Five-time USRA National Champion (two G7, one G27, two G7 Senior)
Two-time G7 World Champion (1988, 1990)
Eight-time G7 King track single lap world record holder
17B West Ogden AveWestmont, IL 60559, ( 708) 203-8003
mikeswiss86@hotmail.com (also my PayPal address) 
Note: Send all USPS packages and mail to: 5858 Chase Ave., Downers Grove, IL 60516
Make checks out to Chicagoland Woodworking, Inc.


#7 kvanpelt

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Posted 24 February 2017 - 04:17 PM

They crack very very easily.

 

As did the head on my Fiat X1/9. Twice!

 

I could have used Swiss's shrink back then, instead I took up slot cars!  :dash2:


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#8 havlicek

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Posted 25 February 2017 - 07:04 AM

There are some very very thin discs that are used by those in the dental field, maybe 1/3 or even 1/4 as thick as the Dremel "thin" discs. They cut very precisely, and while they are fragile (duh!), they do stay together fine if you're careful. I have used them to cut "poly" neos as well as cobalt magnets.

* It is a freakin' mess, but so is cutting creamics, and so is honing.

* As John mentioned, the dust does some weird things. I had a minor "flareup" cutting the solid neos with a diamond disc, but not with the cobalts, and it was an eye-opener!
*They are both fragile, and even ceramics can "toss a chunk" when you get close to cutting-through. Go slow, let the cutter do the work.

Having said all that, I try and avoid cutting or even honing any kind of magnets, but especially neos (solid or "poly") and cobalts. I rarely get to use cobalts at all, so that doesn't come up very often.

 

If anyone asked me, I'd tell them NOT to cut cobalts or neos, but then again, I do other stuff I'd tell people not to do also.


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#9 chasbeeman

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Posted 27 February 2017 - 01:23 AM

Thanks for all of the expert advice. I am glad to have so many knowledgeable builders in one place!

 

Long live Slotblog!


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Charles Beeman

#10 Phil Hackett

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Posted 02 March 2017 - 03:03 PM

Another thing to keep in mind: Cobalt dust. Not good to be breathing. Wear a mask at the minimum AND use water.


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