On 6/26/2014 1:26 PM, Greg Guarino wrote:
On 6/22/2014 12:47 PM, Larry Blanchard wrote:
On Sun, 22 Jun 2014 12:18:20 -0400, Greg Guarino wrote:

Absolutely use both. IME, even those old "finish" sanders that don't
orbit should do nicely for your final grit as long as you sand with the
grain. Especially important to either dust or blow off each piece after
each grit.

This one (an old Rockwell) orbits.

Make sure the "orbit" is random. I seem to remember the orbits were not
random. If you use one of those you'll get cross-grain scratches.

Well it isn't random, of course. These sanders predate Random-Orbit
action by over a decade. As far as I know, most "rectangular" sanders
are still not "random-orbit". Which is why I asked my original question.

OK, some of the OLD orbital disk sanders were essentially a disk
spinning on the end of a drill, like a grinder. You do not want that.

For the most part finish sanders are typically only orbital, not random
orbit, however their pattern is so small it does not matter. ROS's
sanders are a nice alternative to using a belt sander when you want
something that can be more aggressive than a finish sander but still
almost have the same finesse as a finish sander.





Was everything that was machine-sanded before 1982 (and considerably
after, as ROS sanders didn't replace everything else all at once)
covered in nasty cross grain scratches?

The crux of my question was "can I profitably use orbital (not random)
sanders for finer grits?" My purpose is to avoid changing grits on my
(one) ROS repeatedly (or setting up each set of parts repeatedly) as I
sand the 56 (mostly very small) pieces that make up the frames of my
current project.

A couple of people have said yes, which makes sense to me as I never had
a ROS before recently and I don't remember poor results with the
Orbitals I used before. Of course, most of that work was with fine grits
on ply and some S4S trim. Or maybe I never looked closely enough?

I'm inclined to set up the three sanders I have with 120, 150 and
(perhaps) 180 for all of the Red Oak I need to sand. I'd use the ROS for
the coarsest grit, mostly to remove the planer marks from the
store-bought S4S lumber.

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