Just finishing up a shop-built air cleaner/outfeed table/downdraft table (based on a design by charlie b - thanks), and with it running on low, my manometer readings show almost twice the pressure drop that a typical furnace is designed for.
I'm pretty sure the blower is over-sized for this application. Even on low speed, it moves a lot of air. But there's no reason to change it now; it works. I'll use it unless and until the motor does fail.
Just curious whether I might expect it to run for a long time. Or....... expect to see smoke coming out of it anytime.