Hello Everybody,
I am new to this forum, and was going to wait until I was further along with this project before I posted anything on it, but with all the activity around tranny winding lately, I decided to go ahead and put my ideas out here.
I have been intrigued with the idea of a powdered core audio tranny for some time. The cost of producing a core suitable for audio seems to be prohibitive, since I’m not aware of any. That doesn’t mean they don’t exist somewhere, I just haven’t seen them. Either way they’re not readily available to the diy’er.
I hope to change this injustice.
The first step was to find a suitable material. It has to be iron, not iron ferrite (the material most “iron powder” cores are made of), it has to be readily available, and most importantly (to me anyway), it has to be cheap. The answer to this problem came from a surprising place…your local brake shop. Brakes are made from a material called “grey iron”, and every time a brake drum or rotor is turned, a pile of granular iron drops in a tray. I searched the net to find out the composition of grey iron to see what was added to the raw iron, and the main additive is…wait for it…SILICON. It seems that silicon not only helps or tranny to avoid saturation, it helps are breaks from warping from the heat. Now, I don’t know the exact composition of the iron, but it no doubt will work. And the price ? How about FREE!! Its just waste to the shop owner.
Before I go any further, a word about safety. Iron dust is not to be breathed, even our un-processed bucket of iron has dust in it. ALWAYS wear a dust mask if your playing with it.
The next thing is to process our bucket of dirty brake turnings into our iron powder. I first tried wacking the stuffing out of it with a hammer and cast iron pan. A weekend of effort netted me about pound of dust fine enough for my purpose. This will not do. The solution, I believe, is a simple device called a “ball mill”. Basically it is a small drum filled with steel balls that spins on rollers (I hope to have mine finished this weekend). As it spins around the balls smash the grains to powder. Before it goes in the drum (or frying pan if your more inclined to beat it into submission), I heat it up in my metal furnace ( I have a hobby aluminum foundry) to a cherry red heat, and while hot, pour it into a metal pot. As the iron hits the air, it cools rapidly, hardening it. This does 3 things, first it burns any residual oils off the iron, second, it makes the iron quite brittle for easy smashing, and third it puts a very thin layer of oxide on the surface as an insulator. Once pulverized I’ll re-heat it in the furnace to oxidize the broken edges, but this time I’ll let it cool slowly to anneal the metal back to its natural “soft” state.
Once processed, the powder will be mixed with an epoxy binder, and rammed under pressure into a break-away mold. These details will be worked out when I get there.
Comments and suggestions would be greatly appreciated.
I am new to this forum, and was going to wait until I was further along with this project before I posted anything on it, but with all the activity around tranny winding lately, I decided to go ahead and put my ideas out here.
I have been intrigued with the idea of a powdered core audio tranny for some time. The cost of producing a core suitable for audio seems to be prohibitive, since I’m not aware of any. That doesn’t mean they don’t exist somewhere, I just haven’t seen them. Either way they’re not readily available to the diy’er.
I hope to change this injustice.
The first step was to find a suitable material. It has to be iron, not iron ferrite (the material most “iron powder” cores are made of), it has to be readily available, and most importantly (to me anyway), it has to be cheap. The answer to this problem came from a surprising place…your local brake shop. Brakes are made from a material called “grey iron”, and every time a brake drum or rotor is turned, a pile of granular iron drops in a tray. I searched the net to find out the composition of grey iron to see what was added to the raw iron, and the main additive is…wait for it…SILICON. It seems that silicon not only helps or tranny to avoid saturation, it helps are breaks from warping from the heat. Now, I don’t know the exact composition of the iron, but it no doubt will work. And the price ? How about FREE!! Its just waste to the shop owner.
Before I go any further, a word about safety. Iron dust is not to be breathed, even our un-processed bucket of iron has dust in it. ALWAYS wear a dust mask if your playing with it.
The next thing is to process our bucket of dirty brake turnings into our iron powder. I first tried wacking the stuffing out of it with a hammer and cast iron pan. A weekend of effort netted me about pound of dust fine enough for my purpose. This will not do. The solution, I believe, is a simple device called a “ball mill”. Basically it is a small drum filled with steel balls that spins on rollers (I hope to have mine finished this weekend). As it spins around the balls smash the grains to powder. Before it goes in the drum (or frying pan if your more inclined to beat it into submission), I heat it up in my metal furnace ( I have a hobby aluminum foundry) to a cherry red heat, and while hot, pour it into a metal pot. As the iron hits the air, it cools rapidly, hardening it. This does 3 things, first it burns any residual oils off the iron, second, it makes the iron quite brittle for easy smashing, and third it puts a very thin layer of oxide on the surface as an insulator. Once pulverized I’ll re-heat it in the furnace to oxidize the broken edges, but this time I’ll let it cool slowly to anneal the metal back to its natural “soft” state.
Once processed, the powder will be mixed with an epoxy binder, and rammed under pressure into a break-away mold. These details will be worked out when I get there.
Comments and suggestions would be greatly appreciated.