These photos show a conversion of a Rockwell 14" wood-cutting bandsaw to dual wood- and metal-cutting.  I canned the original 1 HP 1-phase motor and substituted a 1-HP 3-phase C-face motor coupled to a 5:1 worm reducer.  The motor is driven with a VFD to give infinite variable speeds.  The output of the worm reducer drives the saw via a 10-rib J-section V-ribbed (Micro-V) belt.  The pulleys have two steps giving the high and low ranges.  The belt is tensioned with a spring-loaded idler.  The idler arm shifts laterally to align with whichever pulley step the belt is on.  The pulleys are attached to the shafts with expanding collet bushings I made.  They give great concentricity and really hold tight.  I discarded the shaft keys.  The VFD is controlled by a little Bud box on the rear post that contains the speed pot and the on-off switch.  The motor, gearbox, VFD, and aluminum slabs for making the pulleys were all eBay aquisitions.  The saw was $100 from the guy across the street, who in turn got it from a buddy, who in turn got it from a school shop closing.  Bear in mind that you can buy a 2-speed Wilton 14" bandsaw for less than $1000, so the only reason my conversion isn't foolish is that it keeps me out of the saloon.

Rockwell Bandsaw 01.jpg - Overall view with the door off.
Rockwell Bandsaw 02.jpg - view of the drive parts in the base with the belt on the high-speed step.
Rockwell Bandsaw 03.jpg - two-step driven pulley saw with the belt on the low-speed step.
Rockwell Bandsaw 04.jpg - close-up of one of the split bushings.
Rockwell Bandsaw 05.jpg - sketch I drew when making the split bushings.