I was going to use it to re-set the large tombstones but I got them done using what I had cobbled together.
Have you used the mud before? It will be interesting to see if it works as well as sheetrock mud. Red clay may fire hard and glaze the casting.
Once briefly, it was just a swipe across the face of some EXP to see if it would work. I think I'll water the mix down next time, this might be a little too thick to breathe. Since the finish on this is going to be rough anyway, I thought it would be a good candidate for experimentation.
Total failure. About three or four seconds into the pour there was a sand shift that caused my pouring basin to slide off the sprue. I guess it was the center portion collapsing. It's weird three sides were solid. Two of the six flanges were solid. If I try this again, I'll go back to EXP foam and pour it vertical. I think the flow rate was way too slow with a half inch hole in the basin so that will be enlarged.
Bummer. I think you might be right about the sprue opening - once the metal had room to spread out past the end of the sprue it probably couldn't keep up to hold the sand back. Better luck on the next one! Jeff
Definitely mold collapse. Better packing always helps but that kind of failure is almost always from interrupted pour or inadequate feed system which in affect produces the same thing. I've found when I gate into the top of a shape like a disc or a sphere, the cross sectional area of the casting increases rapidly as the metal front progresses and the molten metal can evaporate foam faster than it can be fed. In this case, this is probably aggravated by the thickness of the part. I can't tell for sure but the opening on your pouring cup looks small compared to the sprue and may be a bit of a choke. I've had success with increasing the gate/sprue contact area to reduce the total travel distance (within the casting) of molten metal like below. I know it's more of a PITA to degate, but the sprue and gate tends to fill first and then can feed a larger portions of the part. I also always burry the pouring cup.......gives a little more mold pressure and prevents run outs and cup shifting. -My 2 cents in hind sight. Here's an example of a part cast with a lot of contact area. http://forums.thehomefoundry.org/in...ive-intake-manifold-lid.366/page-4#post-17977 Best, Kelly
I ran out of height in the 5 gallon bucket, made a pile and placed the pouring basin on it and piled more sand around it. When the pattern collapsed the pile shifted and the basin slid off. Ooops Enlarged the hole in the basin to 1". Busy day in the foundry yesterday. My sand bin is empty so that means another busy day today.
I have clamp on extenders for my metal buckets/flasks but before I made them, I had a chunk of Sonatube (cardboard concrete casting tube) that was about the same diameter of a 5-gal bucket that I used for more flask height. Could also just cut the bottom out of another bucket. It doesn't need to fit tight or seal. Here's two extenders stacked. Best, Kelly
I think it retired its debt to you Bonz. It's interesting watching crucibles age. Aluminum duty is so much more kind. Electric furnace even more so but it does make the economics of expending a crucible more enjoyable compared to Denis' reality. I'm yet to wear one out but did break my A10 by carelessly adding a big chunk of cold ingot into a 1/3 full molten heel. I wax on about it in the link below but in hind sight, what really happened was it froze the heel, locked the ingot in place against the wall and then the re-heat expanded and cracked the crucible. It still had a lot of life left in it. The cracks are circled with black magic marker. http://forums.thehomefoundry.org/index.php?threads/cracked-my-a10.478/ It's a little more difficult to preheat ingot with an electric furnace but necessary.........unless the crucible is empty. Best, Kelly
