Weighty question

That is correct - if weight is distributed evenly.

Mis-read. 1320#.

Gramp's shop wrote in news:FZd5r.26576$2q1.16882 @newsfe06.iad:

If the weight is not evenly distributed -- which is likely to be the case with a lathe, since the headstock, motor, drive assembly, etc. are all at one end -- then less, in proportion to the distribution.

Suppose, for instance, that 60% of the weight is at one end, and 40% at the other. No two wheels can bear more than 660 pounds, so at the heavy end, 660 pounds = 60% of the total, so the maximum that can be supported is 1100 pounds, 660 on one pair and 440 on the other.

You could, of course, adjust the sandbags as needed to produce an even distribution.

All caster ratings I've seen are by the wheel, so 1320 is your figure.

-- Learning to ignore things is one of the great paths to inner peace. -- Robert J. Sawyer

Mathematically correct. The casters, however, probably have a fudge-factor built in. They may actually stand a 10% increase over their rated capacity, or 50%, or even 200%.

Larger wheels/casters will bear a greater load (usually) plus make the thing even more mobile.

The OP is likely okay, but, nevertheless, he should keep his toes from under the thing.

Unless made in China, then the fudge factor may work the other way.

I sure wouldn't push the specs of a caster, US or Chiwanese. It doesn't pay.

-- Learning to ignore things is one of the great paths to inner peace. -- Robert J. Sawyer

"HeyBub" wrote in news:6oqdnVj8LJaxY8jSnZ2dnUVZ snipped-for-privacy@earthlink.com:

Correction: they are *supposed to* stand such increases over their rated capacity. If the casters under discussion are those available for a few bucks at Horrible Fright, I think it's something of an open question whether their actual load-bearing capacity even reaches that on the label, let alone exceeds it by some presumed but unspecified -- and unknown -- margin of safety.

a lathe, since the

proportion to the

other. No two

the total,

While the 1320# may be correct for a static load, I think the vibration will cause a faster deterioration of the castors, thus decreasing the load they will support.

Have you considered other methods of damping the vibration such as springs, rubber shims, etc. ie placing the lath on a secondary top and supporting the secondary top with the dampening system.

While not the weight you are looking at, I find that my grinder sounds better and I can keep thing on the bench, when I place rubber shims between it and the work bench.

I have a workbench that is a 30" X 52", it has a shelf and small cabinets at each end. The base and the top perimeter is made out of 2X4 with half lap joints. I suspect the average weigh on the wheels is a little over 400#. (Lots of tools, other junk, and there is a lot of space to fill.)

I used castors with about a 300 pound rating. With a static load, these castors served me well for about 15 years. When they died the rubber split radially and basically fill apart.

capacity. If the

Fright, I think it's

reaches that

unknown -- margin

There is ample evidence to suggest that, from drywall to baby formula, there is no word for "safety" in Chinese, at least when it concerns exports.

All the suggestions you have received about wheel rating apply as well as the non-uniformity of the load.

Here is another consideration: When moving the lathe on an uneven floor (even a little uneven) there will be times when only three wheels support the load and , Murphy's law, it is only one wheel on the heavy end.

Good luck,

Bill

And it's always on perfectly level floors. There's something very wrong if you need all that weight to dampen vibrations.

Thanks, guys. All good suggestions. The lathe weighs about 80 pounds and the stand about 40. Adding about 300 pounds of sandbags for some added stability. 1,320 lb aggregate capacity ought to serve me well.

Mathematically correct. The casters, however, probably have a fudge-factor built in. They may actually stand a 10% increase over their rated capacity, or 50%, or even 200%.

Larger wheels/casters will bear a greater load (usually) plus make the thing even more mobile.

The OP is likely okay, but, nevertheless, he should keep his toes from under the thing.

Also, I aim at no more than 50% of the rated load on the wheels. It will move much more easily than a unit right at the wheel's load maximum.

-- Jim in NC

On Mon, 5 Mar 2012 18:44:04 -0700, Gramp's shop wrote (in article ):

You need to design for only two of the casters carrying the load (think uneven floor). Three points define a plane, but when the load toggles between two of the four wheels, the other two will be carrying 100% of the load (although this condition is very transitory). Most of the stress will be applied when you are wheeling the lathe around.

-BR

What everyone else said, but I would build a cabinet with drawers and such and weigh it down with tools and whatever. My shop has no room for sand bags.