It was a nice try. There is a way to make that part where it will not need the big riser. And that would be to run it with the core vertical. Not really difficult. The riser needed would not need to be so tall. maybe 2 inches above the casting. Take a spoon and dig out a reservoir a couple inches deep and a couple inches diameter next to the ingate. Use a short runner to save metal. Put all the part in the drag. Drawing the pattern, might need to wiggle it out of the sand, but you could do it. The core print in the cope may be am issue, needs a tiny bit of draft. The pattern would need to be spot on up and down, and you would have to be able to lift the cope straight.
Would this work poured with cope and drag standing on end, filling through a hole on the top side, sort of like those small cast iron flasks?
I think the plan is feasible. But, I think the shrink defect would be no less likely. It is not a function of head pressure. It is just plain brute force of contracting metal drawing a vacuum after the gate is frozen and the part continues to solidify/contract. Denis
I did dig out a 23-pound (casting+sprue+riser) casting this morning. It used the chunky riser shown around post 5 above. Here is how it drew: The defect is about an inch deep and equal in volume to my thumb from the joint to the tip. That metal was going to come from somewhere. Had that riser not collapsed, I surely would have had an ugly vacuum defect. Denis
Ya, I tried pasting them in directly which SEEMED to work on this end as the images still looked fine. But something happens in formatting in the forum software that must have prevented everyone else from seeing them. Fixed now I hope. Denis
No, the direction and rate of solidification as well as the pressure at lowest point are completely changed, If this was a production piece this would be the way I would go, with a green sand core instead of the cope and drag are run as before, only the pattern is turned. If you turn the piano leg and look at it as it will look installed, you will see where the parting line will be. I'll see if I can draw something up. My drawing will be crude That looks good.
I think it would be interesting to try it this way Foundry rat. I'll make another pattern and try it.
the green sand core...attention to draft, 5 to 7 degrees inside. You will want to split the difference in order to hold closest to dimension/tolerance measure. That is to say figure your draft from the middle or midway of the green sand core to lessen the dimensional change. If measured from the ends, the fit could be sloppy, or too tight. I hope I am clear on this, hard to explain without a drawing. Ben
Ben, The dimentions are not too critical as there is a machining allowance for bore and outer surfaces. i.e. it will be machined all over. I think I can get away with a cylindrical core just sitting in a core print.
Pattern would be soild and split on the parting line. Core placed vertical in a core print in the drag.
MyFordBoy, Saw your YT video, nicely done. Watching you mo(u)ld never get old... Saw this in the USN foundry manual, reminded me of this thread, what were those sailors up to? https://maritime.org/doc/foundry/index.php
looks like brass. I make a similar part in aluminum. Mine is a housing, gets machined all over. Goes to Koch, chicken processing. Don't think the navy is doing chicken though : ) A bearing perhaps? I'll see if I can find the pattern and post it
take it from the sailor in the house, thats Bronze, probably Navy "G" you can tell by the black cottage cheese look of the riser top, brasses are smoother or have some wiggly white stuff V/r HT1
I can't tell hardly copper alloys apart in color, let alone from black and white pictures... Wondering if the original pattern would have worked with larger gating, more like as shown in the Navy picture.
Had sucess today. Still using the elecric furnace with linited capacity. I like the challange! New split pattern. Core is placed vertical in the cope in the recess left by the pattern.
