I'm working on a few new castings but also making some of the routine stuff. It was hot yesterday but I managed four pours. Original Threads on those parts here. Automotive Oval Air Filter | Page 3 | The Home Foundry Automotive Water Neck | The Home Foundry Best, Kelly
Wow. Really, wow. It's encouraging you are able to do that without a million dollars worth of equipment.
I find it absolutely amazing that you're able to cast those water necks without any binder or additional support for the cores.
rocco, After the sand is vibrated to support the foam, it becomes the core inside the foam.. As the metal burns out the foam it supports the core. It doesn't need any additional support because there's no way it can collapse. A least I don't think there is.
I like the little square of foam on the longer arm. I take it that it helps the longer arm to fill better.
That water neck was my original motivation in pursuing lost foam casting. I've mentioned the following before, but although there is no binder in the dry sand, when vibrated, the sand becomes fluidized and flows into a very tightly packed state, which acts as if it is loosely bound due to friction and mechanical interference between the grains. The position and orientation of the part can have a big influence on the stability of the mold because as the pattern is evaporated, it is replaced by molten metal and the hydrostatic pressure helps retain the mold. If you dont have a continuous pour, allow the cup to empty and experience a gap in the pour, it usuaully results in mold collapse. Though barrels are a convenient flask, they also encourage vertical orientation and top down feeding of the part, which I would never do in open cavity casting. But in LF casting, the rate at which the metal advances is dictated by the rate of evaporation of the pattern, not gravity and the cross sectional area of the feed system. This type of feed system also means the hydrostatic pressure increases as the metal advances deeper into the mold, which is helpful because the metal is the coldest at that point. As a final benefit, the casting tends to have great directional solidification from the bottom up, which, if the casting is reasonably uniform wall, is why I almosty never experience shrink defects. People mistakenly think the refractory coating is structural mold support, but it really is only a very minor contributor in this regard. Moreover it controls the rate at which the evaporated pattern gases escape and the molten metal advances and replicates the detail of pattern surface finish. I think LF is a wonderfully practical process for hobby casters and I may have never discovered that were it not for that water neck, but you do need to become adept at pattern construction. -Still cant believe it works so well......LoL! Best, Kelly
