You are most welcome!
Well,I only had limited time with it at SEMA, but I can assure you that it is nothing like the Flex XC 3401VRG.
First off, the Rupes stroke diameter is
massive, (8mm for the Flex, 21mm for the Rupes). The Rupes doesn't steer the pad when it encounters curves or machine tilt, since it is random orbit (nothing really new there).
RPM/OPM ratings are nearly the same (4,800 actual for the Flex, although Flex rates it at 9,600, whereas the Rupes lists 4,200 RPM.
It's easier to compare the Rupes to another random orbital.
The engineer spent a lot of time balancing the machine. It is sensitive, so much so that a difference of 5 grams (.18 ounce) is noticeable! Whether or not this is a good thing... we shall see. The thing is, even with a heavier pad (we compared two identical pads, except one had been used awhile, so it had some buffing liquid absorption into the pad), the machine is smooth, and we were using it at 4,200 RPM.
I'm looking forward to trying the machine out with the DA Microfiber Discs and Surbuf pads. Rupes does make their own specialized backing plates, so perhaps I can find one that'll allow me to exchange the current one for one that will account for the lighter DA Microfiber Discs (at least I am guessing they are lighter). Even if they don't make one, I can drill some holes into the supplied plate to either lighten or add weight to it (via buttonhead countersunk bolts, and washers if needed).
The Rupes guys have put a lot of effort into slowing random rotation down, in hopes of avoiding too much rotation. Their philosophy is that if the backing rotates too quickly, the chance that edge digging of the disc or pad could occur, leaving a less than perfect finish.
While I have been a big fan of the most rotation possible, I can see their point. Still, I'd much rather deal with too much rotation as opposed to not enough. To slow rotation, one seemingly simple way they've done this is to allow a rubber shroud to rub against the backside of the backing plate (the Skorpio Palm Sander also is built this way). The friction helps slow the rotation. I'll have to get a couple extra shrouds, so I can cut one to allow for no rubbing! The design also maximizes vacuum capability on machines designed for dust collection. That being said, I prefer very little rotation for slow speed final polishing, and have been known to drag my finger against the pad or plate to control rotation.
The benefits of a large orbit are numerous. For one thing, more centripetal force is created as the backing plate orbits, so the backing plate will rotate more than a similar machine featuring a smaller stroke diameter.
Next, for every rotation of the driveshaft (or every RPM/OPM), the entire pad and backing plate travels at a higher rate of speed since it is traveling more distance than a machine featuring a smaller stroke.
I could go on and on about machine stroke... OH WAIT!
I already have!:
Machine Stroke - How It Affects Sanding and Polishing Performance
