Magnetic base adventure this morning!

[cathead]

My Mitutoyo magnetic base has been pretty good for quite a few years until just lately when the
handle broke off that turns the magnet inside the base. It's just plastic and snapped off without
applying what I thought was too much force. I ended up taking the unit apart and pulling the
magnet to clean out any chips that may have dislodged inside. After cleaning, removing and
regreasing the base, the magnet was somewhat weaker......After a lot of experimentation
with some neodymium 1/2 x 1 x 2 magnets, I found out how to restore the magnet to even better
than new. The flat sides of the neodymium magnets apparently are the poles, at least that is
the way they are on my magnets. I placed one magnet on each vertical side of the mag base
using north pole on one side and south pole on the other. After rubbing the magnets back
and forth several times, I removed them and found the mag base was indeed better than ever.
The broken plastic handle was heated with a torch to melt the broken surfaces and pressed together
while the plastic edges were still melted. I reinforced the plastic handle with some aluminum bent
over the plastic and glued it on with some Gorilla glue.
When the glue hardens, I will clean off the excess and maybe even paint the handle, not sure yet on that.
Here is the mag base and the two magnets I used to restore the magnet inside the mag base. I can tell you, you DO NOT want to get those
two magnets stuck together! I had to mount them in a vise and pry them apart with a piece of wood after which I will be sure they stay some distance apart.


Anyway, it was a fun experience this morning so I thought I would share for those of you who have had similar difficulties.

 

[brino]

Very interesting.
I had heard that disassembling those bases could cause loss of magnetic holding power.
I am still not sure why, but glad to hear of a fix.
Thanks for posting!
-brino

 

[graham-xrf]

Magnets (used to) die if you disassembled the kit!

The original magnet materials from 1930's was magnetic carbon steel, alloyed with tungsten, and also came to include chromium. Widely used in magnetos, they depended on the metal magnetic "circuit" through the armatures to remain magnetized, and they were prone to weakening. Those who did not know would disassemble a magneto, and lose more than 2/3 of the magnetism in fractions of a second. Sadly, I did exactly this. Re-magnetizing is by imposing an overwhelming field. You always needed a "keeper" of soft iron across the pole of these

Later we came to know "AlNiCo" magnets, letting you know the elements in them. Much stronger, and capable of being more permanent, they were a game changer, and still outperform modern magnets in that they remain magnets even when heated beyond red. Now, of course, we have Neodymium, another game changer. The principle behind what is in those DTI stand switch-on-able/switch off-able magnets apparently has some subtle design aspects. Getting it to work with some power may be a matter of some adjustment, because it seems unlikely the one shown would have Tungsten steel magnets.

Here is a picture of my magneto restoration - doing the wrong thing! Nearly all the magnetism was lost in milliseconds!



And then forcibly re-magnetizing using two neodymium magnets, plus all my screwdrivers to help complete the magnetic circuit. I had to leave them in there as I pushed a circular keeper disc in from the other side. Then I pushed the armature in. I have since learned one can re-magnetize from the outside, putting the powerful field across the magnet, and then putting in the armature.



.. and what it took to work with these things, strong enough to injure!



I have several of those stands, but I never took one apart yet. I am thinking you should not have had the "lose all the magnetism" syndrome, but something like that must have happened, because you were able to restore the strength. Absolutely agreed on handling these things. They can fly together and break fingers, or squeeze on your hand to pain. Especially do not let them pinch you! I could only safely introduce them to each other using the MDF tool!