This seems rather clear intuitively, but my intuition has been known to
fail me: If I am using 4 casters for a 400lb gross weight table w/
machinery, will 4 100lb casters be right (putting aside issue of location
of each caster for the moment)? Or, is there a rule of thumb that each
caster should have X% capacity above its share of the load?
I am considering some simple Harbor Freight casters. The table I need to
move will not be moved regularly -- just when I need to rip something 8'
long.
The table is already built (recycled from another use). I am trying to
keep the casters as small in diam as possible to keep the overall height
down.
>This seems rather clear intuitively, but my intuition has been known to
>fail me: If I am using 4 casters for a 400lb gross weight table w/
>machinery, will 4 100lb casters be right (putting aside issue of location
>of each caster for the moment)? Or, is there a rule of thumb that each
>caster should have X% capacity above its share of the load?
You take the total capacity of all 4 casters and compare it to the total load.
Of course, you have to allow for any imbalance that exists or might occur.
Without knowing if the 100lb. capacity is a true 100lbs., your best bet is to
build in a wide safety margin, say a minimum of 50%. I'd even be tempted to
double the capacity versus the load.
Rich S.
"Igor" <[email protected]> wrote in message
news:[email protected]...
> This seems rather clear intuitively, but my intuition has been known to
> fail me: If I am using 4 casters for a 400lb gross weight table w/
> machinery, will 4 100lb casters be right (putting aside issue of location
> of each caster for the moment)? Or, is there a rule of thumb that each
> caster should have X% capacity above its share of the load?
Capacity is not a big problem, wheel diameter and construction is more
important, IMO. Any four quality casters can handle the load. The problem
with small casters is they do not work well unless the floor is near
perfect. A wood chip can stop them. Just like going over a curb, a wagon
will have a problem, a truck tire much less so, but a 4' diameter tire has
no problem at all.
I have a table with 2" casters. They will be replaced by 4" soon for the
reasons I mentioned.
Ed
Yeah...!!!! Well actually the larger Hard rubber wheels worked out OK but
you run into the issue of raising the tool too high. My old TS sat a good
3" taller than my present Cabinet saw on its mobile base..
You might consider looking into replacement wheels direct from HTC. Those
small diameter wheels and casters are small and hold up to the weight real
well and roll over irregularities in my concrete floor with little feed
back.
"Igor" <[email protected]> wrote in message
news:[email protected]...
> On Mon, 01 Sep 2003 04:48:54 GMT, "Leon" <[email protected]>
> wrote:
>
> >Something to consider... I put casters on my first TS... The held
> >together...... but they developed flat spots when they sat for any
period
> >of days... I replace with bigger harder wheels and that worked out OK...
> >So steer clear of anything softer than rock hard.. ;~)
> >
> Something Fred Flinstone might use?
Which firm did you work with?
On Sun, 31 Aug 2003 04:30:28 GMT, "C Carruth" <[email protected]>
wrote:
>I am also dealing with caster issues, and have spent time on the web
>emailing customer support desks and talking with local caster companies.
>Truth is, the type of caster is very important, which depends on the floor
>type, the temperatures, presence of grease/acid, etc., how fast the
>equipment will be moved, and whether it will be moved gradually or quickly.
>My suggestion is to talk with the experts - companies that make casters for
>industrial equipment. In my case, they recommended 4 casters with 250lb
>rating, made of phenolic plastic. It is overkill in terms of weight rating,
>but at $4.87 per caster, I have piece of mind.
>
I am also dealing with caster issues, and have spent time on the web
emailing customer support desks and talking with local caster companies.
Truth is, the type of caster is very important, which depends on the floor
type, the temperatures, presence of grease/acid, etc., how fast the
equipment will be moved, and whether it will be moved gradually or quickly.
My suggestion is to talk with the experts - companies that make casters for
industrial equipment. In my case, they recommended 4 casters with 250lb
rating, made of phenolic plastic. It is overkill in terms of weight rating,
but at $4.87 per caster, I have piece of mind.
"Igor" <[email protected]> wrote in message
news:[email protected]...
> This seems rather clear intuitively, but my intuition has been known to
> fail me: If I am using 4 casters for a 400lb gross weight table w/
> machinery, will 4 100lb casters be right (putting aside issue of location
> of each caster for the moment)? Or, is there a rule of thumb that each
> caster should have X% capacity above its share of the load?
>
> I am considering some simple Harbor Freight casters. The table I need to
> move will not be moved regularly -- just when I need to rip something 8'
> long.
>
> The table is already built (recycled from another use). I am trying to
> keep the casters as small in diam as possible to keep the overall height
> down.
Igor wrote:
> This seems rather clear intuitively, but my intuition has been known to
> fail me: If I am using 4 casters for a 400lb gross weight table w/
> machinery, will 4 100lb casters be right (putting aside issue of location
> of each caster for the moment)? Or, is there a rule of thumb that each
> caster should have X% capacity above its share of the load?
>
> I am considering some simple Harbor Freight casters. The table I need to
> move will not be moved regularly -- just when I need to rip something 8'
> long.
>
> The table is already built (recycled from another use). I am trying to
> keep the casters as small in diam as possible to keep the overall height
> down.
>
Something to consider is that no floor is perfectly flat and
no cart has four wheels perfectly in one plane. Therefore
the load will be shared by three wheels a good share of the
time. As the cart is rocked imperceptibly from side to side,
the load momentarily is shared by two wheels.
Also the center of gravity of your load won't be perfectly
in the center of the wheel pattern. At the most, load the
wheels to 1/2 their nominal rating. Less if you are going
to move it much.
Rico
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On Sun, 31 Aug 2003 03:23:48 GMT, "Edwin Pawlowski" <[email protected]> wrote:
>
>Capacity is not a big problem, wheel diameter and construction is more
>important, IMO. Any four quality casters can handle the load. The problem
>with small casters is they do not work well unless the floor is near
>perfect. A wood chip can stop them. Just like going over a curb, a wagon
>will have a problem, a truck tire much less so, but a 4' diameter tire has
>no problem at all.
>
I can see it now: My table with 4' wheels -- or maybe just 30". Kind of
like a wheelchair setup. Or some old vendor carts. Yes, I can see how
that would be smooth. Gee, I wonder of there is a cheap source for beat-up
wheelchairs I could recycle?
Well, in my current situation, we are talking about moving the table a few
feet -- my shop is only 13x20 or so. More like that old pocket-sized game
where you move the tiles around w/in a frame to get them in order. I
_will_ have to look out for those wood chips! Many of them are suicidal,
jumping out just as they see you coming.
>I have a table with 2" casters. They will be replaced by 4" soon for the
>reasons I mentioned.
>Ed
>
Thanks. Appreciate the points you made. -- Igor
On Sat, 30 Aug 2003 17:11:11 -0400, [email protected] wrote:
>[snip]
>
>I don't have a clue on how to rate these things. Especially if the
>casters are chiwaneese. Having said that, I made a base for my
>JWBS-20 using casters rated at 125# each which is about what it
>weighs.
>
>Then I started thinking about what would happen if one failed since
>having a corner drop > 4 inches across a 2' x 3' rectangle with a 6'
>tall piece of machinery attached. In my case, I think it would tip
>over and I would be sick for months.
>
>So, I screwed two boards to frame that are just a bit shorter than the
>height of the wheels. So if a caster breaks, the saw would only drop
>1/2" I'm not good at ascii art so I hope you see this in your mind.
>By cutting a ramp on opposite ends of each board, I can tap in a
>wedge to secure the saw in place.
>
> O-----------------------O
> | [ ] |
> | [ ] |
> | [ ] |
> | [ ] |
> | [ ] |
> O-----------------------O
>
>O = caster
>| = wood
>-/| = angle steel frame
>
>Hope it helps,
>
Well (as usual) the ASCII did not help ... but the text did. Makes sense.
Actually, I had been thinking of something similar with bolt-adjustable
feet so I can lift the wheels up -- since I will rarely move the thing (I
think) and this way I can skip cost of lockable wheels. Your wedge idea
sounds simpler, yet effective. Indeed, rather clever. Thanks.
Just to be clear, you used 4 125lb casters for a unit that weighs _in
total_ 125lb? Does it roll well? Are they cheap casters?
In article <[email protected]>,
Igor <[email protected]> wrote:
> This seems rather clear intuitively, but my intuition has been known to
> fail me: If I am using 4 casters for a 400lb gross weight table w/
> machinery, will 4 100lb casters be right (putting aside issue of location
> of each caster for the moment)? Or, is there a rule of thumb that each
> caster should have X% capacity above its share of the load?
>
> I am considering some simple Harbor Freight casters. The table I need to
> move will not be moved regularly -- just when I need to rip something 8'
> long.
>
> The table is already built (recycled from another use). I am trying to
> keep the casters as small in diam as possible to keep the overall height
> down.
There are a lot of unkowns here. First of all, is the manufacturer's
load limit an absolute maximum or does he include a safety margin? Are
some manufacturer's pushing the limit for advertising purposes (low cost
but high load limit?).
Another important questions are whether the load is evenly distributed
over the casters or not. A 400 lb machine will put a 100 lb load on each
caster only if the weight is evenly distributed. Also, what is the
nature of the floor? Is it smooth and regular of does it have lots of
bumps and such? In your case, we can assume that there are no steep
inclines, which otherwise would be a factor.
Also, if there is a failure, generally, only one caster will fail and if
it is, for example, a 4" caster, that does not mean that the table will
fall 4". The wheel, bearing or axle pin (not the caster mounting
bracket) are most likely to fail and the maximum drop would be the
distance from the floor to the bottom of the mounting bracket. If the
load was evenly distributed and the table was not moving at a high rate
of speed over a large bump (or dip), the table would probably sag but
would be unlikely to be in danger of falling over.
So, in general, I think for intermittent use in a home workshop under
most conditions, you could use casters rated for the maximum dead weight
load (table plus equipment) divided by four.
When a reputable manufacturer rates a caster at, for example, 200 lb or
use on a concrete floor, the rating is for an evently distributed load
moving at a normal walking or towing speed (no more than 3-5 miles an
hour) and occasionally passing over expansion joints and threshold
plates.
--
Regards,
Benoit Evans
On Sun, 31 Aug 2003 04:30:28 GMT, "C Carruth" <[email protected]> wrote:
>I am also dealing with caster issues, and have spent time on the web
>emailing customer support desks and talking with local caster companies.
>Truth is, the type of caster is very important, which depends on the floor
>type, the temperatures, presence of grease/acid, etc., how fast the
>equipment will be moved, and whether it will be moved gradually or quickly.
>My suggestion is to talk with the experts - companies that make casters for
>industrial equipment. In my case, they recommended 4 casters with 250lb
>rating, made of phenolic plastic. It is overkill in terms of weight rating,
>but at $4.87 per caster, I have piece of mind.
>
Sounds good. What store?
Igor <[email protected]> wrote:
>This seems rather clear intuitively, but my intuition has been known to
>fail me: If I am using 4 casters for a 400lb gross weight table w/
>machinery, will 4 100lb casters be right (putting aside issue of location
>of each caster for the moment)? Or, is there a rule of thumb that each
>caster should have X% capacity above its share of the load?
[snip]
I don't have a clue on how to rate these things. Especially if the
casters are chiwaneese. Having said that, I made a base for my
JWBS-20 using casters rated at 125# each which is about what it
weighs.
Then I started thinking about what would happen if one failed since
having a corner drop > 4 inches across a 2' x 3' rectangle with a 6'
tall piece of machinery attached. In my case, I think it would tip
over and I would be sick for months.
So, I screwed two boards to frame that are just a bit shorter than the
height of the wheels. So if a caster breaks, the saw would only drop
1/2" I'm not good at ascii art so I hope you see this in your mind.
By cutting a ramp on opposite ends of each board, I can tap in a
wedge to secure the saw in place.
O-----------------------O
| [ ] |
| [ ] |
| [ ] |
| [ ] |
| [ ] |
O-----------------------O
O = caster
| = wood
-/| = angle steel frame
Hope it helps,
Wes
--
Reply to:
Whiskey Echo Sierra Sierra AT Gee Tee EYE EYE dot COM
Lycos address is a spam trap.
Igor <[email protected]> wrote:
>Just to be clear, you used 4 125lb casters for a unit that weighs _in
>total_ 125lb? Does it roll well? Are they cheap casters?
4 x 125 unit weighs ~ 500 lbs. Rolling is not as nice as tool box
casters with ball bearing axles. As far as cheap, 2.99 each so yup,
cheap. Biggest issue with rolling is that machine is top heavy so
anything like a nail can be a problem as a potential tip over.
Tonight I ran into a 16p nail on floor and the saw stopped immediately
with a slight tipping action. Not a problem since I expect issues
with moving a bandsaw on a mobile base and go slow and hold on tight.
Wes
--
Reply to:
Whiskey Echo Sierra Sierra AT Gee Tee EYE EYE dot COM
Lycos address is a spam trap.
On Mon, 01 Sep 2003 04:48:54 GMT, "Leon" <[email protected]>
wrote:
>Something to consider... I put casters on my first TS... The held
>together...... but they developed flat spots when they sat for any period
>of days... I replace with bigger harder wheels and that worked out OK...
>So steer clear of anything softer than rock hard.. ;~)
>
Something Fred Flinstone might use?