Discussion in 'Sand Casting' started by Melterskelter, Feb 13, 2021.
More than one way to skin a cat
One thing I did to make mating the cope and drag easier was to use a small mirror strategically positioned so I could see the notch in the cope and in the drag and the 1/2" pin as I was guiding the cope onto the drag. The problem is that the cope is modestly heavy---40 pounds or so and is large enough that when held close to your chest it blocks the view to the hinge pin. By putting a mirror in the right place you can see the approach of the cope to the drag and get good initial alignment. Once the cope rests on the pin it is self-guiding. One of the reasons I used this system is that the casting is only 1/8" thick, so side-to-side registration has to be held very accurately. The pin and tab system used seems to help maintain alignment well.
Hmmm, I am not sure that what I wrote will make any sense. I tried. ;-)
Top work Dennis!
Lots of useful tips for me in this thread,
Cool project! There are a lot of ways to skin a cat. I am lazy and would have just used a side riser or a smaller spherical shaped riser on top with a generous radius around it at contact. You are only feeding the size of the shrink you have in castings so usually not much bigger than the size of the shrinkage is needed. You got it right with no shrink though and that is what matters.
Yes, my initial plan was to make a little side riser on each of the four areas that shrank. But then it was just easier to make a large rental riser an tap it 4 times with the “x- shaped riser/pouring basin/gate. Since I’ll be doing this over and over I think this actually takes me less time than fiddling with placing risers, cutting gates and cutting runners.
The initial run of parts passed inspection by the customer. So, as soon as my electric furnace is set up and I’ve made another clamshell flask set, away we go.
Could you sketch what you would have done?
These are not great but just a general concept. If you do a side riser you can gate into it to keep hottest metal in riser. If you use the top riser you can create a hot spot in the top by cutting a v-notch groove across the top of it....make it get real small and tight in the bottom to create the hottest pocket of sand you can to keep it feeding longer. You can use the runner for a riser if it is close enough to the casting and the casting is in drag and runner in cope and ingates are thick enough to feed. The biggest reason for failure on risers is creating hot spot where it connects or having it in the wrong spot or having it lower in the mold than the part you are trying to feed. It usually is not due to being too small.
I did this in too big of a hurry...the notch should be deeper.
Thanks, Billy. Now I am trying to imagine how to apply those thoughts to my project.
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