i have a 14" jet lathe with cast iron legs and i mounted the legs in 8"
of concrete and on 6" and above peices i get vibation. this happens
mostly when hollowing a bowl. does anyone have a solution? thank you,
Tom

At what stage of the turning are you getting vibration? green or dry.
Is the head lock positively on? About the headstock release?
Is the blank well balanced? When you have nothing mounted on your spindle
what is the ± wobbling reading.

wrote in message
oups.com...
i have a 14" jet lathe with cast iron legs and i mounted the legs in 8"
of concrete and on 6" and above peices i get vibation. this happens
mostly when hollowing a bowl. does anyone have a solution? thank you,
Tom

wrote in message
oups.com...
i have a 14" jet lathe with cast iron legs and i mounted the legs in 8"
of concrete and on 6" and above peices i get vibation. this happens
mostly when hollowing a bowl. does anyone have a solution? thank you,
Tom


Balance and speed. Lots of people think it's some sort of macho thing to
brag about how much weight they put on their lathe to keep it from shaking
loose, but the best thing to do for both you and the machine is to get best
balance early. Means time at the bandsaw or the chainsaw getting close to
round, and angling the end grain cuts under to get rid of the dead weight
you'll be cutting off to match the curve anyway.

Takes care of the leverage. Difference in mass acts in proportion to the
distance from the axis of rotation. Now get the speed down. Start sloow
and well-held, especially with help from the tailstock. My lathe has eight
speeds from 200 to 3600. I use two. Three sixty starts bigger
out-of-balance stuff, and everything finishes at 690. It's a luxury I
appreciate after my old 12" with 600 minimum.

If you made your own stand you could let good Physics and Geometry lessons
help you design it to spread forward to counter the thrust of the heavy
portion coming over the top, with weight down near the floor behind, where
it'll want to lift at the same time. Not that you'd want to neglect the
above, because Newton says a collision is a collision, and it all happens in
your bearings.

I have the same lathe WITHOUT any extra weight, and I have 13 in bowls run
smooth as cream.

How about some more information--

What's vibrating? The lathe itself or the work surface?

Does the lathe vibrate without any work on it?

Are you talking about vibration when you first mount the piece (before
you've rounded it?)

Do you expect to mount any piece of wood on the lathe turn on the power and
have it run smoothly because of the extra weight?

I do everything I can to reduce vibration by balancing the piece before
turning it on, because I think of the problem of replacing overloaded
bearings.

Try asking this question on rec.crafts.woodturning and see if you get some
other answers.

Walt Cheever


wrote in message
oups.com...
i have a 14" jet lathe with cast iron legs and i mounted the legs in 8"
of concrete and on 6" and above peices i get vibation. this happens
mostly when hollowing a bowl. does anyone have a solution? thank you,
Tom