1/14 CAT 390D LME

[doodlebug]

Hey Jeff, thick and thin area's in a casting will alway's be a shrinkage problem. What I'm wondering is, can you cast the edge thick, and clean it up on a belt sander, to get the curved radius, on the leading and trailing edge? Just a brain cramp!

Cheer's, Neil.

[Jw.]

Originally Posted by doodlebug

Hey Jeff, thick and thin area's in a casting will alway's be a shrinkage problem. What I'm wondering is, can you cast the edge thick, and clean it up on a belt sander, to get the curved radius, on the leading and trailing edge? Just a brain cramp!

Cheer's, Neil.

Ah yes the shrinkage problem I designed my track pad and links .015" per inch oversize. To account for the 3/16" shrinkage per 12 inches for aluminum that I was going to use. Now though I will be using zinc, its 5\16" per 12 inches. So its now undersized just a hair.

About casting the edge thicker I think it might work but now you have to make sure you sand each leading and trailing edge on all pads to match each other perfectly so they mesh. That would be a job for someone with a really good eye and steady hands.

[Jw.]

I did some research on the plaster of paris and its moisture content. The plaster is calcium sulfate hemihydrate(contains water). So yes molten metal plus water equals mold failure and or a steam explosion but only until it is heated above 392°F, it forms into anhydrite(does not contain water).


First plaster mold with no imperfections.