Bowls exploding on lathe

[Dusty Sawyer]

It goes without saying that they guys who sold me the face shield knew what they were talking about when they said, "and never take it off". I had a 13" bowl almost finished on the lathe today, but had to take if off to do something else. When I put it back on, I could not seem to get it to spin round again and resolved to scrape the outside to make it so.

Twice before when I have done this, it ended badly with wood flying and loud bangs that caused the LOML to come running. Is working the outside of a bowl that is almost finished just a bad idea or what? I am wondering if anyone has had the same result?

Thanks

 

[Wildwood]

Have not had much luck trying to turn wet mulberry bowls lately.

1st. after reversing the bowl in chuck, almost finished with inside, stopped to sharpen my goughe for final cutsl, came back had a catch, gave me mall shaving scar on chin, when it shattered.

2nd. after reversing the bowl in chuck, working inside, had to stop and ca gule an inclusion and knot about 3 inches long to keep it from flying off. Same op when to the grinder, came back, slowed the lathe down, got a catch, bowl flew of the chuck, new crack on other side of the bowl. I had my face shield on, and didn't get hit!

3nd, attempt ended up a small oval candy dish!

Three bowl blanks, one candy dish, two pieces of fire wood, and one shaving scar. Guess you can say wet mulberry got the best of me. Oh, not only wear my face shield now, also wash it when done using.

 

[cskipper]

I've only had one or two really fly off the lathe, but it happens. I've not successfully re-chucked anything (of course, neither have I successfully made more than one bowl that wasn't a candy dish and paper clip holder - not the original intended use). Folks that turn more will undoubtedly have more insight. Glad you didn't get hurt! That's a very scary few seconds because you have to realize what happened and that all parts have landed. Don't let it keep you from trying another.

 

[edspec]

Bowl flying off the lathe are way too common in my shop. It seems that after you turn the outside it is very risky to return to the outside after working the inside. Heat generated (green wood ) when turning the inside rapidly causes a warp to the over all bowl. It will never rechuck the same. The temptation to add or modify that last little detail is when I get the most bowl flinging catches.

Smaller bowls hurt less when they hit you but a face shield is always a good idea. Note: All face shields are not IMPACT RESISTANT check to make sure the ANSI IMPACT RESISTANT label is there. Safety glasses under the shield would seem overkill but resistant is not proof.

Steve

 

[Dusty Sawyer]

Steve,

That makes sense to me, have heard (recently) that rechucking to turn the outside was bad because the piece would not handle it. But what you said adds the rhyme and reason behind the results.

Thanks Much !

 

[Sir Chiz]

Rechucking a bowl shouldn't be a problem if the walls are thick enough to avoid cutting through the warp to the inside. ;-)
Use a cutting tool instead of a scraper. Start at the bottom (foot) and work out toward the rim. The foot warps less than the rim, and will give you a smoother starting point,and you can undercut the warp avoiding the tool bouncing off of the high spots.

Flying bowl parts is less exciting than flying chuck parts. 8-O ;-)

 

[Wildwood]

I use a Talon scroll chuck, and normally don't have a problem remounting a bowl blank if it comes out of the chuck while turning. Doesn't happen that often, but sure surprises me when it does.

If get a catch and throw the blank across the room, but still safe to turn will remount the blank.

If get a catch, and destroy the blank, throw all pieces in fire wood bag.

If get a catch, and blank can not be turned safely, goes into fire wood bag.

Normally start by drilling a 11/32" hold in what will be the inside of the bowl. Then mount the woodworm screw in the chuck, screw the bowl blank on and turn out side of bowl. Depending upon design will either turn a tenon for compression or recess for expansion to hold a bowl blank when it's reversed into chuck jaws. Have no trouble with either compression or expansion method of holding a blank in the chuck.

Also use a home made donut chuck to finish turning the bottom.

Most of my problems stem from trying to rush. I be seeing, but not paying close attention when oops happens!

Realize my bowl like me has a fat bottom, and trying to work both inside and out side to solve that problem.

Also if bowl goes oval, (wet wood) while turning, before getting to final 1/8" or 3/16" of an inch, still try to work may way on both out side and inside.

In both case should just accept the fact the bowl will be a bit shallow and just work the outside to completion.