how to slotting on a bar magnet?

[DreamCat]

Hi all,

I got a lot of linear Hall IC from one of my friend, but it is almost useless. Most of the time, I use logic output type in my designing, not liner type. the only thing that I'm doing with them is making a Hall compass. there are many problem need to resolve(maybe I have to give up it), here are two question:
1, how to sloting on a bar magnet? for collect the geomagnetic.
2, the big problem, how to cancel out the high magnetic field comes with Ferromagnetic objects? of course, I have read some document of honeywell's product. but how I can do?

[Parmin]

Slotting of a magnet could be done with a dremel tool
Cancelling magnetic field is tough, I think it could be done by using another magnet placed behind it in opposite field.

[DreamCat]

@Parmin, It need about 5mm depth of slot, but it will be broken when I cutting the bar magnet. Now, I want try to etch a slot with acid.

[pickit2]

why not make a metal frame and set one or more magnets into it.

[solutions]

Just epoxy it to a bar of plastic, if you must, prior to your slicing and dicing. Wear a mask, because some magnet materials are not conducive to you living very long.

Why are you bothering with this when a flux gate magnetometer is what you should be building, IMO? Hall effect devices are more useless than you seem to think. They mention the Honeywell AN-203 magnetometer used in the iPhone 3GS here http://en.wikipedia.org/wiki/Magnetometer#Fluxgate_magnetometer

[Parmin]

The one time I design retail security system (something line clothing tags) I need magnets with holes on them.
The client wants a non standard sized hole for security reason.
So I have to cut and slots normal ceramic magnet and the newer Neodymium stuff using dremel tool with diamond bit, never crack them unless you are forcing it.
On hard material, you should let the diamond bit do the work grinding out the hole rather than you force it to cut.
Dont forget to drip in some coolant tho! I use water on a spray bottle.

5mm deep is nothing, I have to cut through 20mm thick, and it took about 45 minutes!!

[DreamCat]

all are good idea. LOL, I was too stupid on it.
the bar magnet, I means ferrite materials, I .. forgot word "ferrite", sorry.
It seems that Parmin's method is best, It just need a little hole to place IC. I will try it tomorrow.
the epoxy resin is simplest way, but there are not small package for sale. I think I can use some epoxy glue for it.