jscpm
Titanium
- Joined
- May 4, 2010
- Location
- Cambridge, MA
When turning on centers, a source of error is non-collinearity of the center holes.
Most people, myself included, just chuck up each end of the bar and drill it from the tailstock, but the problem with this strategy is that if the bar is not collinear (which it never is) then the centers will not be collinear either. So, the question is: is there a better mousetrap for drilling centers?
If you think about it, one idealistic idea would be to first face both ends of the bar and then lap them parallel on a surface plate. If the bar was then indicated in the chuck so that the face was orthogonal to the ways, then you would at least be guaranteed that the centers would be parallel. They might still be offset, but would be parallel.
To make them aligned X-Y as well, would be much more tricky. It's hard to see how to do that easily.
Most people, myself included, just chuck up each end of the bar and drill it from the tailstock, but the problem with this strategy is that if the bar is not collinear (which it never is) then the centers will not be collinear either. So, the question is: is there a better mousetrap for drilling centers?
If you think about it, one idealistic idea would be to first face both ends of the bar and then lap them parallel on a surface plate. If the bar was then indicated in the chuck so that the face was orthogonal to the ways, then you would at least be guaranteed that the centers would be parallel. They might still be offset, but would be parallel.
To make them aligned X-Y as well, would be much more tricky. It's hard to see how to do that easily.