After reading several articles with their own subjective evaluation of
ROSs, I decided to apply a simple numeric test to compare two of them
and I was surprised by what I found. I hope you find this interesting
and useful to decide your next ROS purchase.

The fairly straightforward logic goes like this:

1. Unlike disk sanders, each grit particle on an ROS moves in a more or
less circular orbit, and ALL of them move in the same orbit (as long as
the pad is not spinning wildly)

2. Call the orbit diameter "D" and the OPM (orbits per minute) "R".
Simple math tells you that each particle travels a distance of pi*D
inches per orbit, and pi*D*R inches per minute, or pi*D*R/12 feet per
minute.

3. To compare, say, the Ridgid R2610 with the PC 97366 and with a belt
sander, consider this:
- the R2610 has R=1/4 and R (max) = 10000 in aggressive mode. This
gives the particles a speed of 655 feet/min
- The PC97366 has R=3/16 and R(max) of 6000, giving it just 295
feet/min.

Incidentally, the amperage on both is about the same too.
Startled? I sure was.

-Ram

wrote in message
3. To compare, say, the Ridgid R2610 with the PC 97366 and with a belt
sander, consider this:
- the R2610 has R=1/4 and R (max) = 10000 in aggressive mode. This
gives the particles a speed of 655 feet/min
- The PC97366 has R=3/16 and R(max) of 6000, giving it just 295
feet/min.

But what do the numbers tell? Do they factor in the dust collection ability
and its effect on finish? Orbits under a given pressure? Does a longer
stroke = better finish or just faster cutting? Factor in weight and comfort
in the hand as that becomes very important when sanding a lot of surface. Is
the ROS with the highest feet/min the best?

I think some more testing is needed to show a correlation between your
numbers and actual results in various situations.

As for the amperage, no, I'm not startled It is not the amps, but what you
do with them that counts.

In article .com,
wrote:

After reading several articles with their own subjective evaluation of
ROSs, I decided to apply a simple numeric test to compare two of them
and I was surprised by what I found. I hope you find this interesting
and useful to decide your next ROS purchase.

The fairly straightforward logic goes like this:

1. Unlike disk sanders, each grit particle on an ROS moves in a more or
less circular orbit, and ALL of them move in the same orbit (as long as
the pad is not spinning wildly)

2. Call the orbit diameter "D" and the OPM (orbits per minute) "R".
Simple math tells you that each particle travels a distance of pi*D
inches per orbit, and pi*D*R inches per minute, or pi*D*R/12 feet per
minute.

3. To compare, say, the Ridgid R2610 with the PC 97366 and with a belt
sander, consider this:
- the R2610 has R=1/4 and R (max) = 10000 in aggressive mode. This
gives the particles a speed of 655 feet/min
- The PC97366 has R=3/16 and R(max) of 6000, giving it just 295
feet/min.

Incidentally, the amperage on both is about the same too.
Startled? I sure was.

-Ram


That is really interesting, I am going to be very interested to see
where this thread is going to go.

The intial knee-jerk reaction is to ignore the amperage for now as Edwin
stated, "it's what you do with the amperage."
The R2610 doesn't have a gearbox, the PC doesn't have 'self powered'
dust collection. I know both machines really well.
I'm thinking if there is some way to test these machines in a scientific
way. Repeatable.
The mechanical impedance 'z' is important as well. I was given a
Craftsman 1/2 sheet sander once. The body was so light, that the paper
remained mostly stationary and the body vibrated like nuts. So even
though the amperage and stroke distance were there, there sure as hell
wasn't any sanding going on. So the non-moving mass is a very important
item. (The PC has a completely different weight distribution than the
Ridgid.) The bulk of the non moving mass is much further removed from
the centre of the paper on the PC than the Ridgid. There is a lot of
**** going on all at the same time.


Cool

Rob

And on the same principle as filing aluminum, you can skid over with a
courser cut than a finer one, I have noticed that on acrylic, in some
cases, a 180 grit paper cuts better (more aggressively) than a 120.

wrote in message
oups.com...
After reading several articles with their own subjective evaluation of
ROSs, I decided to apply a simple numeric test to compare two of them
and I was surprised by what I found. I hope you find this interesting
and useful to decide your next ROS purchase.

The fairly straightforward logic goes like this:

1. Unlike disk sanders, each grit particle on an ROS moves in a more or
less circular orbit, and ALL of them move in the same orbit (as long as
the pad is not spinning wildly)

2. Call the orbit diameter "D" and the OPM (orbits per minute) "R".
Simple math tells you that each particle travels a distance of pi*D
inches per orbit, and pi*D*R inches per minute, or pi*D*R/12 feet per
minute.

3. To compare, say, the Ridgid R2610 with the PC 97366 and with a belt
sander, consider this:
- the R2610 has R=1/4 and R (max) = 10000 in aggressive mode. This
gives the particles a speed of 655 feet/min
- The PC97366 has R=3/16 and R(max) of 6000, giving it just 295
feet/min.

Incidentally, the amperage on both is about the same too.
Startled? I sure was.

-Ram

I suspect the brushes on my now-dead PC 333 have done me a pre-mature
insult. I've discovered that the variable speed settings on the Bosch ROS
that replaced it sure cause a (MUCH) bigger difference in sanding capacity
than I ever suspected/expected possible (the slower the speed the more
aggressive the surface material removal -- with the same grit paper).
Surely the difference caused by 8-hole ventilation (Bosch) vs 5-hole
(Poorly Capable) ventilation can't be suspect here!

Help me see what you're talking about :-/
--
Enjoy life and *do* well by it
-- it might well be the only chance you get :-)

Steve,
http://www.ApacheTrail.com/ww/

wrote in message
oups.com...
After reading several articles with their own subjective evaluation of
ROSs, I decided to apply a simple numeric test to compare two of them
and I was surprised by what I found. I hope you find this interesting
and useful to decide your next ROS purchase.

The fairly straightforward logic goes like this:

1. Unlike disk sanders, each grit particle on an ROS moves in a more or
less circular orbit, and ALL of them move in the same orbit (as long as
the pad is not spinning wildly)

2. Call the orbit diameter "D" and the OPM (orbits per minute) "R".
Simple math tells you that each particle travels a distance of pi*D
inches per orbit, and pi*D*R inches per minute, or pi*D*R/12 feet per
minute.

3. To compare, say, the Ridgid R2610 with the PC 97366 and with a belt
sander, consider this:
- the R2610 has R=1/4 and R (max) = 10000 in aggressive mode. This
gives the particles a speed of 655 feet/min
- The PC97366 has R=3/16 and R(max) of 6000, giving it just 295
feet/min.

I believe that all goes down the tubes when you actually set the ROS sander
down on the wood and begin sanding. Orbits decrease significantly when the
sander is actually working.