Ever had the crap beat out of you by a rough bowl blank that was not only out of round but also out of balance? If your bowl blank is a nice cylinder with flats on both sides then it is in balance, there is no air when taking the first roughing passes, and you can quickly shape the outside of the bowl. But if the blank is not so conforming or has odd shapes then there will be lots of air time and that means difficulty roughing.
Many of us have made jigs to cut blanks into circles on the bandsaw. If you have a big log where a large flat was cut you can get a cylinder. But if your not dealing with a big log or trying to maximize the bowl size there could be dead space and/or irregularities to deal with even after cutting the circle.
John Weaver and I were discussing this and he had an idea to tilt the circle jig at an angle to further shape the blank and eliminate/reduce the amount of variation thereby cutting down air time and increasing balance. So I took a shot at making a jig, this is the result:
There is a little bark left but that is very minimal, one pass will remove all that and this blank balances well enough to turn fast, I started this one at 700 rpm.
You still need to properly prep your blanks with the chainsaw before using this jig. The jig can further improve irregular blanks.