Greetings,
Here is info on my new homebrew bandsaw circle cutting jig. I've used other jigs, and was never happy with the results - so I designed my own. It is capable of cutting circles as large as 108", or as large as your arms and support rollers can support. It is adjustable for blade lead, and has a mechanism for starting the cut into oversized stock.
More text and picture info in a.b.p.w - RE: Bandsaw Circle Jig
FWIW,
Greg G.