Turning Archive 2006

Subject:
Serious, Bowl-Busting Catches.....

Wally Dickerman in Arizona
>The occasional small catch when turning bowls is inevitable, and usually causes no real problem. It's those big bowl-busting catches that are the bane of many turners. They may damage or even break a piece, and they can cause possible injuries. Because I've been teaching classes for so many years, I think that I've seen just about every kind of catch that it's possible to have.

Why do the serious catches happen? There are many ways that a catch can happen, but nearly always it's because of the way the tool was being handled. A large catch is frequently a result of losing control of the tool when a small catch occurs. Any scraping tool, including hand-held hollowing tools, should be held with the handle under the forearm for support. Whenever possible, when using a scraper or a hollowing tool or a bowl gouge, the tool should be tucked in against your side. Move your body to move the tool. The larger muscles in your body do a much better job of controlling the tool than the smaller muscles.

A few things that you should know to prevent serious catches:

When using scrapers the handle should be tipped up a little, so that the butt end is a bit higher than the blade. Shear scraping is an exception....

When scraping on the outside of a bowl, cut below the centerline....

When scraping on the inside of a bowl, cut a little above the centerline....

Catches can occur when a tool is deep inside a hollow vessel, and the cutting edge crosses over the center at the bottom. In effect, the rotating wood is then coming up on the tool instead of down. This lifts the tool, then slams it back down on the tool rest. The result is often a broken rim, and sometimes a sore arm....

Using a scraper near the rim of a thin-walled bowl almost guarantees a catch....

Catches when using a bowl gouge, usually occur when the bevel gets away from the wood. An unsupported cutting edge will dig in.

Allowing the hollowing tool to rub on the rim of a hollow vessel is a sure way to break the rim if a catch occurs....

Many of today's newer lathes are designed with the bowl turner in mind. Shortbed lathes, and rotating and sliding headstocks allow the turner to stand facing the piece when hollowing. This makes it easier to maintain control of the tools, especially when turning hollow vessels.

Wally

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