Casting sand questions

[benmychree]

You're correct - I wrote fireclay, but should have said bentonite - my poor recollection.

You can temper Petrobond with oil that the same company sells for the purpose (so you don't have to discard the blackened portion adjacent the casting) or with Peanut oil. If you don't, your PB degrades a little each time as even the non-blackened parts dry some and the whole mix bonds a little less well. You can 'mull' green sand on the floor, with your feet and a shovel and it will work every bit as well as Petrobond - except that there is no smell and it's easier to maintain.

GsT

Reminds me of Pakistan videos Lots of foot action there!

 

[benmychree]

One thing I don't like about Petrobond is that the water bulb that you can use with green sand to shrink the sand away from the pattern for easy withdrawal of the pattern is not workable, and there is all too much breakout at the parting line of the sand, making cleaning the castings more time consuming. I was making castings for my marine compound steam engines, I made the aluminum and bronze castings, and jobbed out the iron castings to a SF bay area iron foundry, which has gotten too expensive for me; $250 for any two part mold. Found another foundry that likes cash and works much cheaper.

 

[benmychree]

Notice how this guy puts his left foot on the mold when he pours the molten aluminum. I'm thinking that he used to do that with his right foot previously... I get the feeling that does this a lot and has his process down pat. He makes it look simple...

Much better to use flask weights than burn your feet!

 

[Cadillac]

I make greensand with fine beach sand, bentonite clay and I use 2stroke oil to mix. Works good like John said you get alittle bit of smoke but I’m ok with that.

 

[Smithdoor]

They is one sand that works is cemet and sand
It is about 5% to 10% cemet to sand
It same cemet used in concrete mix.

Great for of a kind casting It was use on large machine tool casting till 1950's.

Dave

 

[Lathe_Bender]

They is one sand that works is cemet and sand
It is about 5% to 10% cemet to sand
It same cemet used in concrete mix.

Great for of a kind casting It was use on large machine tool casting till 1950's.

Dave

What liquid do you mix with this - oil, water, etc.?

 

[rwm]

Check out lost foam casting. Depending on the part this might be a whole lot easier to get you started. I have made and casted with both oil bonded sand and water based sand. There is a process to get your sand right and ideally you would have a muller. Lost foam really just requires some pink house foam, some sand, and a bucket! I just cast this piece in lost foam. Yeah it has some porosity but shows the ability to cast a complex part.