Author Topic: Dolphins (Read 580 times)

Powder keg · « **on:** January 28, 2006, 07:43:17 AM »

Could anyone please explain how to build a pattern that would allow me to cast dolphins on a barrel. I think it would need some sort of sand core or something.

Thanks,

GGaskill · « **Reply #1 on:** January 28, 2006, 10:18:08 AM »

Probably the easiest way would be to make the pattern with "lost foam" dolphins so that they were burned out in the process of casting. Do you want to make real dolphins that look like the marine mammal or simple lifting handles?

I am assuming you are talking about making a green sand mould. It would be easy if you are making an investment mould.

Powder keg · « **Reply #2 on:** January 28, 2006, 10:47:42 AM »

Thanks G!

I never thought of adding foam details to my sand casting. It might be trickey to position them on the pattern and have them stay in place when the wood pattern is removed? But I think It is do-able. I was just talking about lift handles, nothing to fancey. Gives me something to think about.

Later, Wes

Cat Whisperer · « **Reply #3 on:** January 28, 2006, 01:47:47 PM »

The foam piece could have a tennon that would fit into a mortise inside the pattern - right along the parting line, so the pattern would come out and off leaving the foam in place.

GGaskill · « **Reply #4 on:** January 28, 2006, 05:10:52 PM »

Since I put the trunnions on the parting line, the dolphins would have to have tennons that fit into the top of the barrel pattern perpendicular to the parting surface (not along the axis of the dolphin) so the pattern could be removed without pulling the "lost foam" pieces loose.

Cat Whisperer · « **Reply #5 on:** January 28, 2006, 05:28:55 PM »

Quote from: GGaskill

Since I put the trunnions on the parting line, the dolphins would have to have tennons that fit into the top of the barrel pattern perpendicular to the parting surface (not along the axis of the dolphin) so the pattern could be removed without pulling the "lost foam" pieces loose.

But if the mortise and tennon were well tapered, they 'should' part easily.

(But then I'm speaking hypothetically.)

kappullen · « **Reply #6 on:** January 28, 2006, 05:53:41 PM »

I have given this some thought as well.

I was going to place the foam dolphins on nails or pins
that are square to the parting line.

The pattern should pull free of the foam with no problem.
Care would have to be taken in the ramming operation.

Put up some photos please and a report so we can all do it!.

Kap

Cat Whisperer · « **Reply #7 on:** January 29, 2006, 08:11:20 AM »

Quote from: kappullen

....
Put up some photos please and a report so we can all do it!.

Kap

Exactly right! We want to learn from your mistakes - so we don't have to make them! :-D

GGaskill · « **Reply #8 on:** January 29, 2006, 08:35:54 AM »

But if the mortise and tennon were well tapered, they 'should' part easily.

Agree, they should be tapered side to side and front to back or conical, but the mortises need to be perpendicular to the parting plane or the foam will be pulled out when you remove the barrel part of the pattern.

Also it will take some care to ram the mould so that the sand is tight enough to hold but you don't damage the foam parts.