On Mon, 17 Jan 2011 13:22:29 -0500, Bob Engelhardt
wrote:

Jon Danniken wrote:
...
On a side note, I played with the little transformer I posted pics of
earlier, using it as a lifting magnet. ...
I turned the power on, and it lifted all 30 pounds, ...

That was my big fun for the day.

Well, I just had some big fun of my own. Based on your report, I had
pretty much dismissed the idea of MOTs being converted to any kind of
serious magnet. But, what the hell, I was curious about the MOTs that I
had converted, so I did some testing.

Mine is a MOT that I had cut in half & used the secondary. The cut
surface was bandsaw flat, but not machined. The core is 2+ x 4+ & I put
a 3/4" plate across the poles. I applied 120v, full wave rectified.

I started out about where you had been: 20-30 lbs. No problem, so I
started adding more. Well, I overflowed the bucket that I was putting
weight in (my MOT collection), switched to a milk crate and filled that
with all the MOTs, plus all the lead I had. Beefing up the lifting
system as I went. I got to 207+ pounds and had to stop 'cause the milk
crate was full and near its breaking point, and the lift system was also
at its limit.

So, I'm going to bring in my engine hoist, scrounge up some more weight
and see just what this baby will do. Not because I think that it might
actually be strong enough for a magnetic brake (it won't be), but "I
gots to know" (Dirty Harry).

Bob

It would also be interesting to see how much force you get when a
non-ferromagnetic gap of 1/16" or so (e.g., .062 aluminum) is
introduced.