When you use different bit styles on boring bars, the size they cut can vary widely, depending on where the cutting tip is tangent to the bar centerline. Checking my own, I found there was a .007″ difference between standard-type bits and the indexable bits. It’s best to calibrate your micrometer to the bit that cuts the largest, then adjust the other bits accordingly. This way, there’s really no way you can cut a bore oversize by accident. Worst case, you add the differential and recut the bore.
Ron Flood
Cedar Machine
North Branch, MN
