Hollowing tool help needed

[chuck vernon]

I am having trouble with catches with my homemade hollowing tool. It is designed to copy the easy hollower. I used a 12mm round carbide cutter. The ahaft is two pieces of 3/8" square stock welded side by side to form a flat wider surface. The cutter is in line with the shaft. I am presenting it at the midline of the bowl. Should I set my tool rest above the midline? I think tool rest level may be ,my problem

[Jim Underwood]

If you're having catches, the tool self feeds because the forces aren't balanced. If you have a wide cutter tilted up into the stock, and the anchor point (where the shaft contacts the toolrest) is offset from it, then the force of the stock will try to drive it down, which drives it into the wood, which.... well it's disastrous.

Does that seem like what's happening?

[Richard Coers]

Cutter is WAY TO BIG! Most everyone uses 1/8" (3 mm) tool steel cutters. So if you want to stay with carbide, get a much smaller one. 12mm (1/2") would be tough to tame for anyone. Also, most hollowing tools have 5/8" or 3/4" bars. You are undersized there as well. Big cutter + small bar = catches and vibration

[Jamie Donaldson]

Actually most hollowers use a 3/16" cutting bit because 1/8 " is too small and too aggressive to control well. Any flex in the shafts creates chatter, and that is a quick prelude for catches!

[Richard Coers]

You're right Jamie. I thought about that fraction as I was typing, but for some reason, 3/16" didn't seem right. I should have known better because I actually have a pivoting holder that I made sitting right here on the computer desk. DOH!

[Richard Coers]

Just thought of something else Chuck. When using any scraper, the handle MUST be higher than the cutting edge. Get too close to horizontal, or have the handle below the cutter, and you'll get catches.