Successful conversion to a metal-cutting bandsaw!
1750 rpm stock motor --> 15:1 Grove gear worm reduction box --> 2" drive to 8" driven pulley = ~30 rpm == ~100fpm saw speed.
The little tilty table for belt tension works pretty nice too. This came with the saw.
I am running a 1/2" wide Lenox bimetal blade. This bandsaw has trouble getting enough tension on a wide blade like this. Blade manufacturers indicate that 15,000 - 20,000 psi is the best tension range for bandsaw blades (at least bimetal ones like this, YMMV). I'll spare ya'll the math, but basically I need my spring to deliver about 200 pounds of force to get this much tension.
Again, sparing the math (PM me if you're interested in it), I calculated my factory spring has a spring rate of about 175 lbf/in. Fully compressed the spring can only create 150 lbf of tension. Also, springs don't really like to be used at total compression, so clearly I needed a bigger spring to hit > 200 lbf.
I chose a heavier die spring with a rate of 340 lbf/in that fits nicely in the space. Factory spring on the RH side below. This spring will be able to generate up to about 300 lbf before reaching maximum compression.
They are aligned enough that they will track when free running, however as soon as I start cutting with it it jumps the wheels. Part of the problem I think is that the bearing and guide assembly is in bad shape / non existent. The story I got from my coworker who dropped it off was "The old lady I bought it off said it runs perfect and she'd just used it recently. She makes small wood crafts with it." When I took the panel off I discovered it had no tires at all on the wheels and there were lots of scoring / gouges in the wheels where she'd been running it for quite a while with no tires.
N8kImNK by cgutierrez22, on Flickr
