Machining Magnets
 

Hi guys. I need to machine away the corner of a neodymium magnet that needs
to go into a hole in a mold. One of the passages for a core intersects the
hole the magnet is going to get pressed into. There really isn't any other
place to put the magnet, and the core is a necessary part of the casting.

Any tips or suggestions?

The best thing I can think of is to just use the little bench top belt
grinder.

The problem is if the prototype is satisfactory I may find myself making a
bunch of these molds. Hand grinding one is no big deal. 20 or a hundred...
well that could be pretty time consuming.

I know they are fragile. That's why I think grinding is the best option for
just one. I do not want to put a grinding wheel on one of my mills, and the
little no-name mill drill still comes in handy from time to time (I used it
today), so I'm not crazy about filling it up with grit either.

Machining Magnets
 

On 18/10/17 22:05, Bob La Londe wrote:
Hi guys.Â* I need to machine away the corner of a neodymium magnet that
needs to go into a hole in a mold.Â* One of the passages for a core
intersects the hole the magnet is going to get pressed into. There
really isn't any other place to put the magnet, and the core is a
necessary part of the casting.

Any tips or suggestions?

The best thing I can think of is to just use the little bench top belt
grinder.

The problem is if the prototype is satisfactory I may find myself
making a bunch of these molds.Â* Hand grinding one is no big deal. 20
or a hundred... well that could be pretty time consuming.

I know they are fragile.Â* That's why I think grinding is the best
option for just one.Â* I do not want to put a grinding wheel on one of
my mills, and the little no-name mill drill still comes in handy from
time to time (I used it today), so I'm not crazy about filling it up
with grit either.




What I've read about those magnets is that they aren't recommended for
machining as the dust is easy to ignite. Also if using to hold a core in
a mould IIRC the magnetic properties are lost at low temperature of less
than 100C so you may be better off looking for another solution.

Machining Magnets
 

"David Billington" wrote in message
...
On 18/10/17 22:05, Bob La Londe wrote:
Hi guys. I need to machine away the corner of a neodymium magnet
that needs to go into a hole in a mold. One of the passages for a
core intersects the hole the magnet is going to get pressed into.
There really isn't any other place to put the magnet, and the core
is a necessary part of the casting.

Any tips or suggestions?

The best thing I can think of is to just use the little bench top
belt grinder.

The problem is if the prototype is satisfactory I may find myself
making a bunch of these molds. Hand grinding one is no big deal. 20
or a hundred... well that could be pretty time consuming.

I know they are fragile. That's why I think grinding is the best
option for just one. I do not want to put a grinding wheel on one
of my mills, and the little no-name mill drill still comes in handy
from time to time (I used it today), so I'm not crazy about filling
it up with grit either.




What I've read about those magnets is that they aren't recommended
for machining as the dust is easy to ignite. Also if using to hold a
core in a mould IIRC the magnetic properties are lost at low
temperature of less than 100C so you may be better off looking for
another solution.


https://www.kjmagnetics.com/neomaginfo.asp
"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."

Machining Magnets
 

"David Billington" wrote in message ...

On 18/10/17 22:05, Bob La Londe wrote:
Hi guys. I need to machine away the corner of a neodymium magnet that
needs to go into a hole in a mold. One of the passages for a core
intersects the hole the magnet is going to get pressed into. There really
isn't any other place to put the magnet, and the core is a necessary part
of the casting.

Any tips or suggestions?

The best thing I can think of is to just use the little bench top belt
grinder.

The problem is if the prototype is satisfactory I may find myself making a
bunch of these molds. Hand grinding one is no big deal. 20 or a
hundred... well that could be pretty time consuming.

I know they are fragile. That's why I think grinding is the best option
for just one. I do not want to put a grinding wheel on one of my mills,
and the little no-name mill drill still comes in handy from time to time
(I used it today), so I'm not crazy about filling it up with grit either.




What I've read about those magnets is that they aren't recommended for
machining as the dust is easy to ignite. Also if using to hold a core in
a mould IIRC the magnetic properties are lost at low temperature of less
than 100C so you may be better off looking for another solution.

***********

Igniting dust could be an issue. Thanks.

If it holds until the mold closes its fine. No its not holding the Teflon
(or sometimes brass) core pin in place. ;^) They just both need to occupy
the same space at the same time, and since I have not yet mastered phasing
matter, then grinding some away is the next best option.

Using a magnet in this type of application is a tried and true technique.
Most just don't use it because they are mass producing and time is money.
For custom its well worth it. Maybe less so if every magnet has to be
customized.

Machining Magnets
 

"Jim Wilkins" wrote in message ...


"David Billington" wrote in message
...
On 18/10/17 22:05, Bob La Londe wrote:
Hi guys. I need to machine away the corner of a neodymium magnet that
needs to go into a hole in a mold. One of the passages for a core
intersects the hole the magnet is going to get pressed into. There really
isn't any other place to put the magnet, and the core is a necessary part
of the casting.

Any tips or suggestions?

The best thing I can think of is to just use the little bench top belt
grinder.

The problem is if the prototype is satisfactory I may find myself making
a bunch of these molds. Hand grinding one is no big deal. 20 or a
hundred... well that could be pretty time consuming.

I know they are fragile. That's why I think grinding is the best option
for just one. I do not want to put a grinding wheel on one of my mills,
and the little no-name mill drill still comes in handy from time to time
(I used it today), so I'm not crazy about filling it up with grit either.




What I've read about those magnets is that they aren't recommended for
machining as the dust is easy to ignite. Also if using to hold a core in a
mould IIRC the magnetic properties are lost at low temperature of less
than 100C so you may be better off looking for another solution.


https://www.kjmagnetics.com/neomaginfo.asp
"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."


*********

Well since it looks like ordering a shorter length magnet to go in the hole
is a better option I looked and found that KJ magnetics has rare mags rated
for high temperature use. Now to see if there is somebody who can get them
here in a day or so for less than $74 shipping.

Machining Magnets
 

"Bob La Londe" wrote in message ...

"Jim Wilkins" wrote in message ...


"David Billington" wrote in message
...
On 18/10/17 22:05, Bob La Londe wrote:
Hi guys. I need to machine away the corner of a neodymium magnet that
needs to go into a hole in a mold. One of the passages for a core
intersects the hole the magnet is going to get pressed into. There really
isn't any other place to put the magnet, and the core is a necessary part
of the casting.

Any tips or suggestions?

The best thing I can think of is to just use the little bench top belt
grinder.

The problem is if the prototype is satisfactory I may find myself making
a bunch of these molds. Hand grinding one is no big deal. 20 or a
hundred... well that could be pretty time consuming.

I know they are fragile. That's why I think grinding is the best option
for just one. I do not want to put a grinding wheel on one of my mills,
and the little no-name mill drill still comes in handy from time to time
(I used it today), so I'm not crazy about filling it up with grit either.




What I've read about those magnets is that they aren't recommended for
machining as the dust is easy to ignite. Also if using to hold a core in a
mould IIRC the magnetic properties are lost at low temperature of less
than 100C so you may be better off looking for another solution.


https://www.kjmagnetics.com/neomaginfo.asp
"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."


*********

Well since it looks like ordering a shorter length magnet to go in the hole
is a better option I looked and found that KJ magnetics has rare mags rated
for high temperature use. Now to see if there is somebody who can get them
here in a day or so for less than $74 shipping.

*********

McMaster to the rescue. LOL. They were typically outrageously more
expensive, but they had some much higher temperature neodymium mags that
will work ok, and I needed to order some fill in drill bits, teflon rod, and
a couple other things from them anyway.