Appreciation post: The old guy at the Pittsburgh foundry show who showed me his riser trick

I was at the Pittsburgh foundry show last fall and got talking to this retired pattern maker. He saw me looking at a casting with some shrinkage and asked if I used a double riser. I told him no, I just used one big one. He took a piece of chalk and drew on the floor how he puts a smaller riser right next to the main one on heavy sections. Tried it on a 200-pound gear blank pour last week and the sound changed when it fed, no shrinkage at all. Has anyone else used this setup for thick castings?

2 comments

2 Comments

paige_harris1d ago

What's the spacing between the two risers?

max9631d ago

Have you checked if your local building code has a rule for this? Mine says the gap can't let a four inch sphere pass through, which is a safety thing for little kids. That means your risers need to be less than four inches apart. A lot of people just guess, but getting it wrong could be a real problem later. You should look up the exact number for your area before you build anything.