I'm currently using a 125mm dia Makita random orbital and although the results are good it does take quite a long time when sanding out scratches on full 8x4 veneered sheets on both sides with 180grit. I've seen a few sheet orbital sanders that have 3x the sanding sheet size but they are all non-random.
If I use a palm sander I end up with swirl marks that turn up after I've applied the final wax-oil finish; it's even more evident with the walnut veneers.
Do sheet orbital sanders leave swirl marks with 180-grits, and does having a more powerful sander with a large sheet sand quicker than a small ROS?
(Welcome to the forum.)
Yes, they will--> but any type of orbital or radial sander will with 180 grit. 180 grit is fairly rough and is not a finish grit. After a 180 grit, then go over with 240 then 320 grits.
With veneers, then are already smooth, depending how they look, I start out with 320 or 240 grit. It you start them out with 180 grit, you are going making them un-needily rougher than they are, just to try to get then smooth again-- then you also risk sanding them thin.
The reason this is true, and more noticeable over hand sanding or an old electric block sander, it that with those two methods, you sand with the grain. With the aforementioned sanders, you get some cross-grain sanding... which to hide, you really have to go smoother, to hide in the finish stage. It you just think basically, this may dissuade you from... But Orbitals do such a good good and are very fast. Personally, I don't like spending my time sanding... I would rather spend my time doing other things... So faster and better sanding by an orbital sander is a good thing.
If your eyes or feel cannot see swirls or scratches well, wipe your work with thinner, wood conditioner or a damp cloth and the sanding marks, scratches, etc, with be amplified while wet. Be sure to let dry before sanding again.