In article .com,
"bizHB" wrote:

the lathe itself weighs 200lb and the bench im building weighs about
another 100lb. is that enough to make it not dance with me while
turning big off center/not balanced pieces? or should i fill the two
pockets i made with sand to add another 50lb total?

Build it, mount a 30 inch off-center/unbalanced blank, turn it on, stay
out of the way, apply lessons learned to building mark II...nothing
quite like experience if you've come to be asking this question at this
point in the build, rather than before starting...

FWIW, my piddly little 20-inch swing lathe weighs in at over 800 lbs.

Weight-wise, you are in the same range as a ShopSmith (180-200 lbs or
so) plus a 100-lb bag of chicken feed laid on the ways. That happens to
be a combination I've actually turned on, and I would not care to try it
with a 30 inch swing, never having approached the Shopsmith's 17 inch
swing - however, that setup is also limited by small spindle size and a
low speed that's too high. It would dance with a piece of firewood you'd
have a hard time getting a 4 inch cylinder out of.

Given the limitations of the internet as a communications medium, I
admit I could be judging you harshly - perhaps your setup is well
designed, and has a nice slow speed drive system with a beefy spindle,
yet does not weigh much, and will actually work fine. If so, consider
going to the local reloading supply place and getting some shotgun
reloading shot, which weighs a bit more than sand, and fill your boxes
with that.

Good luck with whichever of Mark I or Mark II works out for you.

--
Cats, coffee, chocolate...vices to live by