The Unofficial Mamod and Other Steam Forum

Reid · Posted: Sun Jan 27, 2008 7:02 am Post subject:

Any such magnet can be fully recharged, no special fixtures necessary.

You dismount the magnet.

have a compass on hand.

Obtain some enameled copper wire of stout gauge such as 16 or 14.

Wrap the magnet edges with masking tape if the paint is delicate and needs to be preserved.

starting at one end of the magnet, begin winding it tightly with one layer of the wire. I suggest 16ga. as being suitable.

Wind until you reach near to the other end of the horseshoe, taping the wire so it won't unravel at those two ends.

OK, now establish the magnet polarity the simple way for us beginners:

Use the compass to find which pole is which,
and now, test to know the polarity, the which-way to connect the wire ends to a car battery.

DO THIS TEST with a torch cell of 1.5V or so, and see:
which of the two possible polarities AUGMENT the power of the magnet end (N or S, we don't know, and that does not matter) to attract the compass needle.

Ah, so say wire end A, going to D cell + is the ticket;
that connection strengthens the magnet.

OK, now you know how you're to connect to the massive current supply of a car battery.

Here's where care and caution must be used: Wear eye protection, a face shield, just on the off chance of a battery explosion.

Put a keeper, a bit of steel strap, across the pole ends of the horseshoe (this will maximize the charge, better than factory new)

Wear leather gloves because the wire will get so hot in just a trice, that it may well FUSE or burn suddenly apart.

When you make the connections: One connection may be clamped to the battery.

PUT A LEAD ONTO THE OTHER BATTERY POST, and strike your wire to the end of that heavy lead, not to the battery post proper (for you increase the risk of a battery gas explosion.

Don't do this to a battery that's just come off the charger
(Explosive hydrogen gas present)

THE KEY to a recharge is the passage of high current (high ampere-turns in this case) for even a tiny fraction of a second.

The BANG comes by sudden breaking of this instant-on-off circuit.

YOU DO NOT need or want to hold the connection.
It's all done in a flash.

THE RESULTS come when the circuit breaks -instantly-
BEST is if the wire fuses/burns in half at some place.

About equal results come by your striking the contact by a flying pass of the connection wire. Bang, bang, you're done.

You may now unwind the wrapping wire and throw that into the recycle bin.

Your magnet will be at least as strong as when new.
The great initial magnetism will soon fall off though, and continues to fall of as the magnet ages and as it is vibrated in use.

Really good magnet steel of the era was high tungsten carbon steel, fully hardened, hard as glass.
That steel took the best charge and held it longest.

Your motor may now be reassembled.
If you can keep the keeper on until after assembly, so much the better.

And for long-time storage, replacement of the keeper will keep the magnet in prime condition longer.

It's so easy to recharge permanent magnets of the old steel type.

Every one of you now knows how to do it.

The factories had magnet chargers for mass production purposes.
For the one-off job, you can get even superior results by the direct winding of the magnet and use of a 6 or 12V magnet.

Remember: its the -instant breaking- of the current circuit that BANGS the steel molecules into magnetic alignment.
This is why a sudden fusing of either the wire or of a high current fuse, gives, in theory, the best results.

I've charged a dozen or so old radio type horse shoe magnets this way with splendid results every time.

It will get hot. Wear gloves. One bang will do it.

HTH,
_________________
Reid

Steve_S · Posted: Sun Jan 27, 2008 12:20 pm Post subject:

Good stuff Reid, I'll try that. Thanks!

scorpion2nz · Posted: Mon Apr 28, 2008 10:15 am Post subject:

it is a trix motor but the holes along the bottom do line up with meccano but not enough power to be of any great use