DIYbanter - View Single Post - I need a swivel or bearing for a lazy susan style turntable.

lid wrote:
On Mon, 11 Apr 2005 15:35:24 -0400, "J. Clarke"
wrote:

wrote:

On Mon, 11 Apr 2005 07:00:18 -0400, "J. Clarke"
wrote:

I want to be able to spin 100 pounds items on a 24" wide turntable that
will spin freely as long as possible.

Are these items symmetric or asymmetric? Balanced or unbalanced?

Yes.

So one should assume that the 100 pounds will be a point mass at 12 inches

from the center?

The hundred pounds could be any size or shape, but I would only be spinning
cylindrical items of course. I don't make anything over 100 pounds in one piece.
I suspect my hub rated at 3600 pounds should be up to the job.

I would suggest that you re-read John's post again. You are likely
concentrating on the wrong point in his post. Since you aren't saying
that much about the stuff you are doing, one can only guess as he points
out, but the real issue may be whether it will stay on the table or not.
You may want to do a force calculation based on a symmetrical balanced
load (placed at the center), and then estimate forces based on an
unbalanced load -- i.e. on the rim. Somewhere I saw you mention 150 RPM,
and now it is 100 lbs. -- possibly unbalanced -- at the outer edge of a
24 inch rim. As John points out -- you must assume the total weight is
on the rim to do the worst case calculation... I will leave it to the
mechanical engineer in you to worry about the safety issues.

While I could do the calculations I can't be bothered as you seem to be
quite capable of doing them. (Someone might be able to tell us the
velocity of the rim of a 24" diameter circular platform, and the
resultant force of a 100 lb. object. The impulse on a floor if it flies
off a 34" high work bench might be an interesting calculation as well.
:-) Better test it outside. :-) )

The people here are not being dinks -- they are pointing out that you
may have missed some significant design factors.

My last post on this topic.

Thanks for listening.

--
Will
Occasional Techno-geek