Vibration Question

[Russell Dyess]

I was attempting to turn a small plate from a 4/4 cedar board. The cedar board had been air drying in the top of the shop for at least 10 years. After shaping and sanding the bottom of the plate, I flipped it and attached it to my chuck using a mortise. When I spin it up, it spins mostly true. When I start hollowing out the center, the piece starts to vibrate. My question is am I releasing stresses in the wood that causes the vibrations? Note: When I flip the piece, I bring the tailstock up to help center it in the chuck. I also start hollowing on the outer most edge and work into the center to maintain the most mass for as long as possible. Any ideas to reduce the vibrations? Thanks for the input.

[Richard Coers]

Vibration is about weight, not stresses in the wood. Could be a change in the density that is causing the vibratioin.

[Reed Gray]

Another thing that can cause vibrations is too much pressure on the bevel. This is more true with platters, which are generally thinner than bowl blanks. The softness of the cedar can also contribute to it. From an old movie about Cyrano de Bergerac, a famous swordsman after he disarms a student, "Hold the sword as you would a bird. Too tight and you kill it. Too loose and it flies away." Another quote I use, no clue as to who said it, "The bevel should rub the wood, but the wood shouldn't know it." Just the lightest pressure against the wood with the bevel. The second hand, left one for us righties, just rests on the tool. This took a long time for it to sink in for me.

robo hippy

[mike calabrese]

I would call it chattering and not vibration just a nuance doesn't matter here however.
You didn't mention the RPM you were running at , how sharp your cutting edge is and so on. Most important is the touch especially is a soft wood like cedar.

You might check out this guy he goes by the name robo hippy not only did he post just above but he has some great you tube vids have a peek
https://www.youtube.com/results?search_query=robo+hippy+wood+turning
calabrese55

[Russell Dyess]

Thanks to all who responded. I love this hobby and still have a lot to learn.