I assume you are offsetting centers to minimize runout. If that is the case can you explain how you look at a shaft and get it centered. If it is not to minimize runout can you explain why this is done. I get my shafts in dowel form and have always just center drilled them but I would like to learn a way to improve on what I am doing.
Thanks for the info.
To add to what Greg responded with...
1. Take a dowel and look at the face on one end, and find the grain line that is most in the center of the dowel. If you are lucky, there will be a lot right in the center, and you will have to try and find one easily seen that is in the center.
2. Get a good pencil and start tracing it to the other end of the dowel.
3. If the grain line you are tracing completely disappears out of the side of the shaft, it is mostly likely not worth fooling with for that dowel. You can start tracing the center grain line from the other end, and see which one follows the center the longest. One option is make that end the tip end, but offsetting is still not worth that much given the severity of the run off.
4. If the grain line makes it all the way to the other end of the dowel, and is still at the center, smile and center drilling normally.
5. If the grain line makes it all the way to the other end of the dowel, but is all the way over on the edge, offset the center drill on both ends in opposite directions to straighten the line to center it from end to end as much as possible. You can decide which end will be the tip end, and offset that one a little more since you are cutting away more material there anyway. You can't offset the butt ends all that much.
6. If the grain line makes it all the way to the other end, and is only a little off, you can just offset one end of the dowel an appropriate amount.
Up to the individual whether they offset using the eyeball, or use a jig to offset standard amounts. For round shaft dowels, I went the later approach, and made 3 jigs with 3 different offset amounts. When mixing and matching on tip and butt end, it gives me enough options. I offset butt blanks (not the butt end of a shaft, pieces for the butt of the cue) by eyeball since there is usually a lot more meat to work with.
There are several other grading things to look at when doing this as other factors come into play, but this should be plenty to get you started doing this if you feel it is worth your time. Let each shaft tell you what to do.
Kelly