@all
can any one tell me what epoxy to use?

I would not use epoxy. Too thick and not uniform sand dispersion.

Try a slow curing high strength resin like this one.

CR-900 High Strength Casting Resin, 26 fl. oz.

If you could do this under a vacuum, that would be even better.

For a vacuum method, I would do the following. Place the black sand into the form, press it in well. Mix the resin and pour into the mold. Apply the vacuum for 15 minutes then release the vacuum and let set overnight. You would get a very nice form doing this with virtually no bubbles if done with care.

Thanks for that information

Peter.
would you be willing to help with this. I am sure you would know a lot about sand cores and also how to make them. so if you do not mind and are not to busy your help would be wonderful thanks. William.

If you are trying to create a vacuum, remember what Tesla showed us how to do: High voltage, high frequency applied to an enclosed container will (I'm pretty sure) cause the gas molecules to bond with the solid molecules, reducing the pressure.

here's an example:
YouTube - Self-pumped vacuum capacitor effect

You could use a microwave to melt the magnetite and then pour it into your mold.

Place a strong magnet on one end to align the fields as you like as it cools.

Dr. John V. Milewski: Growing Gold from Glass in a Microwave - Part 1

YouTube - Dr. John V. Milewski: Growing Gold from Glass in a Microwave - Part 1

IndianaBoys

While that is very interesting, melting the magnetite would probably destroy the effect one is trying to achieve with the small grain magnetite. He's trying to reproduce the effects covered by Peter.

And I would just use a simple vacuum pump if you want to create consistent results.

Try This

William,

This method was developed by the late Bill Muller for his motors. Make a frame or mold of the exact size of magnetite core you wish to cast, and line it with a material that will allow you to get the core out after it sets up. Make sure the end plates are made of .125 inch plastic sheet. Mix your magnetite with a slow curing, high temperature resin. Mix as much magnetite into the resin as possible while it is still malleable. Fill the mold and place the end plates on each end, and then place a strong, NEO magnet on EACH SIDE of the mold. The NEO magnets should be at least as large as the magnetite core you are making, and should face each other in the attraction mode, so that all of the particles of magnetite line up, and TOUCH EACH OTHER as the resin sets. This also aligns the magnetic domains in the iron so they are all parallel in the finished core.

Any other method yields very poor results.

When the resin is set (24 hours), the magnetite disc should be able to magnetize up to at least 2500 Gauss and operate with a very narrow hysteresis curve. It will be a complete "non-conductor" so "eddy-currents" will be very low.

Bill Muller used these cores in his motors as a cheap substitute for Metglas Cores. They have many of the same high-speed switching characteristics, but their magnetic permeability is much lower.

That is it. No more questions. Good luck.

Peter

Thanks!!

Peter.
Thank YOU!! For taking the time to give all that vary good, and useful information.

I wonder whether additives - Nd or some such - can be used to increase the permeability of the cores and whether this would be a worthwhile thing to look at.

Magnetite Recycling

Hi to All Hope Peter can enlighten me on this
Magnetite core from old crt screen .. can it be ground to powder and follow Muller steps to reconstruct ?????
a lot of it is just junk here in China and my muller project hit the dead end for lack of magnetite

Thanks for the support in this thread


totoalas

Hello,

What should be used in the mold to act as a releasing agent with the slow cure epoxies? Corn starch, something else?
Thanks for the help!



Kevin