Misc Foundry Info

Misc Foundry Info

(Things that don't fit any where else)

Not that I like to dwell on the negative, it's more a matter of trying to find some meaning or lesson when things go wrong. In this case, the picture to the right is my original crucible. I never read anywhere that crucibles won't last forever.

As obvious as it is now that homemade pots should be periodically inspected, it's not self evident when everything is new and exciting.

I remember the event with absolute clarity, it was one of the rare days when I was lax on safety, running shoes, no safety glasses, a couple of friends over, a few pints of ale. None of these contributed to the crucible letting go, but in retrospect are all issues to be avoided while pouring metal, for me anyway.

I had a little over a half pot of metal nice and liquidy when I pulled it out of the furnace. The luckiest stroke was that the crucible ripped in half exactly as shown over the furnace. All the metal landed right onto the coals.

This is one of three Medical Gas tanks that I picked out of the scrap heap at work. Originally they held a gas mix used for calibrating equipment. The HazMat label affixed on the side designated it as an inert gas, and a non-re-fillible container.

The valve assembly is solid brass, and is easily removed with a 3/4" wrench and breaker bar (Pipe).

The tank is approximately 2 1/2 ft tall with a 1/4" welded base. If you're going to check at your local hospital, ask for the Bio-Med department, or Materials Management, since they look so nice but can't be re-filled, they likely have a stack of them and may be glad to be rid of them.

Since the contents were inert, I had no anxiety about cutting the tank apart, though I did remove the valve assembly to ensure that there wre no contents under pressure.

As before, I welded a couple of bolts for lifting and pouring, I didn't have to weld anything to the base as there was a nice 1/2" hole that could be used to tilt with.

The diameter is 4" across and roughly 9 1/2" tall with the walls about 3/16th" in thickness. Understandably I'm a bit shy of having an unweildy amount of metal to move, but this is a great size and very easy to handle with confidence.

This is the only remaining piece from my first truck a mid 70's Dodge Ram, I'm sketchy on the exact year as it was such a mixed bag of parts Lee Iacocca would have been hard pressed to nail it down to a specific year or even model.

The Tranny sat in our yard for a number years helping to perpetuate the inbred white trash hill-billy image that I've spent my life honing. It is a model 727, which became near extinct the day I needed one, it's replacement was located about 3hours in-country in Quebec (almost a different country when you live in Ontario).

I guess that in this state it weighs in around 100 to 125lbs.

It took about 1/2 a day for me to gut it down to this point, unfortunately most of it's weight was in steel parts that were both uninteresting, and otherwise useless for my purposes.

I had visions of at least a half dozen smooth rolling bearing assemblies and numerous steel sub-assemblies that would scream "utility" to me, there were none. The final drive assembly is a solid shaft of approx 1" dia that will work somewhere.

I've had no problem simply beating the alloy pieces into chunks that easily fit into the crucible, though when your a mountain like me I guess it shouldn't pose any real challenge (now that's funny stuff...). At least 2/3's has been melted down in the last 8 or 9 months. Once this is done I've got a 2.8L V6 that I'm itching to pull out and dis-assemble.

Returning to the theme of learning from mistakes, I've included a few pictures of malformed castings using the "Lost Foam" method.

This pulley was oriented opposite of what is pictured (top-down, bottom-up). The irregular surface shown is from an air gap that occurred from either settling of sand or not adequately pushing the mold hard enough into the sand.

Since this snafu, I try and turn and push down and avoid excessive banging of the box once placed.

This defect could easily have been machined out.

This is the Classic "Slow-Pour" defect. I knew I had screwed this up the instant I poured it.

I got spooked by the sound and sight of flames when the metal hit the foam, eased up on the pour to the point that I almost stopped, saw that sand was shifting and then picked-up the pace in hopes of salvaging the casting.

My guess is the the heat of the metal vapourized the foam as expected but the flow of the metal simply wasn't there to take-up the void.

As I've said before, "Fast and Careful".

This is the last of the pictures, though I have numerous other failures I could share, but won't as there is a physical capacity limitation on the Web-Server...

This is the common "Under-Shot" casting. Simply put not enough metal to fill the mold. I hope to see fewer of these with the larger crucible.

I hope that these images and all of the pages under "theworkshop.ca" are of some assistance, or at minimum a diversion from the usual pictures of domestic pets that only the owner cares about or family members that only the family knows.

Support theworkshop.ca

Back to Metal Casting