Knowledge You Can Build On — Est. 1998
Chatter
Gil
>I'm turning some drunken cough drop wood (cherry given the alcohol treatment). While trying to turn the inside of the rough outs to a finished surface I'm experiencing chatter like I never have befor. I use an ellsworth gouge to turn bowls and have never had this chatter problem until now. Has anyone else experienced chatter issues when turning the inside of thin walled vessels? Is this what steady rests are for?
Searching for answers,
Gil
Re: Chatter
Mark Kauder, Phenix City, AL
>IF your problems it the thinness of the bowl wall - yes, a bowl steady will help. Another alternative is (let's not get started on the glove argument) is to hold a gloved hand against the outside of the bowl to dampen the vibration. Alternative to a glove is to hold a piece of thick cloth or leather in your hand to do the same thing.
Mark
Re: Chatter
John Lucas
>Gil
Have you turned thin wall bowls before? Then tend to move, sometimes while turning. They can also chatter do to the thin walls. I often place my left hand on the outside of the bowl to dampen chatter but I can only do this on smaller bowls and would not do it on natural edge.
I usually turn down about 1" to the final thickness and leave the rest of the bowl fairly thick. Then I'll turn down the next inch and blend the 2 areas together. Then do another inch etc until I'm done. I never go back because the wood often moves and you either get chatter or uneven cuts.
Re: Chatter
Gil
>I turned all my previous bowls around 1/4-1/8" thickness. I was trying to turn some spalted cherry down below 1/8" thick, man oh man wood which is not all heart wood and partially rotten likes to move a lot with the tool touching it. Thanks for the advice, still trying to work out the chatter with a light delicate touch.
-Gil
Re: Chatter
Dale Cook
>One other way you might try is grab a handfull of shavings to press against the outside.
Re: Chatter
Brad Vietje
>Gil,
Thin can give you chatter, and spalted makes the wood even weaker. John's advice about working your way slowly down from the rim should help. Another factor is how the gouge is used, the shape of the flute, and the length of the bevel (as well as the sharpness of the edge!). You'll also want to just barely rub the bevel on thinner walls or weaker woods to deform the bowl less -- we can ususlly get away with too much pressure on thicker bowls.
For finish cuts on thin walled bowls, smaller tools may also help. I usually use a 1/4" bowl gouge with a straight-across 45 degree bevel angle (bevel is somewhat cone-shaped at tip). This tool gives a fantastic off-the-tool finish because I sharpen it very often, it has a very small radius at the tip (less resistance ==> less chatter), and a longer bevel at 45 degrees than the Ellsworth grind at about 65 degrees. On open bowls, I usually go as far into the bowl as I can while maintaining good bevel contact. When this tool won't reach, or gets too far over the rest to be stable, I go to a 3/8 bowl gouge with a side grind -- just like the classic Ellsworth grind, but closer to 45 degrees for a finer edge.
All other factors being equal, smaller tools with smaller cutting surfaces ==> less cutting resistance, and less chatter. If the smaller tool reaches too far over the rest, you can get chatter from the flex in the shaft of the tool, so a heftier tool will help.
Safe Spinning,
Brad Vietje
Thetford, VT
