Delta’s current version of their popular “B.O.S.S.” (benchtop oscillating spindle sander) model, the SA350K, retains the B.O.S.S.’s overall design, including its sturdy 18"-diameter round cast-iron table and cast plastic base, similar to the Craftsman. I liked these large, round tables better than other table shapes. There are no corners for parts to hang up on, and a round table supports large or long parts regardless of their orientation.
The overall fit and finish of the Delta is very good, and I liked the removable storage trays that house the sanding drums, table inserts and accessories. The Delta doesn’t include a 1/2"-diameter sanding sleeve with their OSS. That’s odd, since all the other models — even Delta’s old B.O.S.S. models — include one (fortunately, you can buy a regular 1/2" x 4-1/2" sanding sleeve that fits directly onto the SA350K’s spindle).
In use, the Delta exhibited strong, smooth sanding performance, thanks to its 3.5-amp motor, sealed gearbox and mostly metal oscillating mechanism, which features bronze bearings to guide its motor and spindle assembly up and down. This is unlike the mechanisms on all the other OSS machines, which move only the spindle assembly up and down. Even though the Delta’s stroke is very slightly shorter than the Craftsman’s, it sanded with a little more aggressiveness, perhaps due to its rapid 60-strokes-per-minute oscillation — twice as fast as the Craftsman.
The SA350K is the only OSS that includes a dust bag, and it actually provides decent dust collection, thanks to a small fan at the base of the spindle. This lets you run the sander without a shop vacuum — convenient if you’re working outdoors or away from the shop. But the woven fabric doesn’t trap fine, respirable particles. For best collection, I recommend connecting the Delta — or any of the other models — to a shop vacuum or dust collector whenever possible.