I picked up a metal lathe awhile back and been learning to use if for a few months now making simple items I needed for the shop like top punch for my sizer. And I went to price some alum billet 45 bucks for a 2 inch dia 24 inch long to costly to practice on for me. Heck I am cheap main reason I started reloading to save money still working on that plan.
So I got to looking into making my own with scrap so I built me a oil fired burner with a blower and all the items needed to melt it down.
So what I have learned so far all scrap is not the same my first melt was everything from drink cans gutters and what ever piece of alum I had laying around. What I got was alum that was worthless to turn it tore instead of cut and ripped out chunks.
My next try I added some brass to the mix what I got would turn and was fair to work with or practice I cast this batch in green sand I made up my self. Big problem I found was voids right down to the middle not some that would turn out. I degassed and fluxed and my temp was high enough as far as I could tell.
My third try I used some tanks that were tested at 3000 psi nothing added my thinking was it had to be a better grade of metal. Well I got my green sand ready to cast and a few pieces of pipe with no weld seam to fill. I poured several different sizes so I would have a mix to pick from for my stock. All looked well until I chucked up one of the green sand pour to clean it up and see what I had to work with. It cut will and I got nice chips with a smooth finish but voids not as many but still to many to use it for anything useful. I was getting kind of down about the entire effort and decided to check out one I pour in the pipe. I had two voids and it turned very well cutting clean and smooth only issue I found was I would get a mirror finish for a section then dull then mirror again. I think this was caused by a chip rubbing work piece but as of now I am just trying to get workable material.
So I think the voids in the green sand casting was moisture in the sand causing the void oh my homemade green sand is well sand cat litter and water until it holds it shape not oil or store bought casting sand. The voids in the pipe one I think was cutting oil or chip left in the pipe since they were right at the out side of the material.
I have seen U Tube where people have cast different item with sand and turn it on a lath to make a pulley or gear and that turn out fine from what I can see so anyone have any input on what may be causing my voids with that method. And I plan of casting using pipe since I got good results with that so far just to build up some stock.
So if anyone else here has been down this road any advise would be great not much to find on the net as to fixing problems just people say look what I did.