Remember when we had to guess on the riser height for those big steel castings?

Back at the old Johnson Foundry in Toledo, we always had trouble with shrinkage on the big gear blanks, the ones about 18 inches across. The book said to use a riser 1.5 times the section thickness, but we still got pulls. One real hot day about eight years back, I was fed up and just packed a little extra sand to make the riser a full 2 times the thickness, almost as a joke. Poured it, let it cool, and knocked it out... perfect. No sink. We ran with that for every big job after that. Anyone else find their own little number that worked better than the old rule?

3 comments

3 Comments

mason.drew27d ago

Always thought the book was gospel until a similar trick saved a big pour last year.

sandragrant27d ago

It's funny how that works, @mason.drew. Sometimes the best tricks are the ones you learn by doing, not just by reading.

jana50927d ago

Ugh, tell that to my student loan debt.