Sometimes my laziness tries to get in the way of doing things properly. For instance, there have been numerous times where the proper way of approaching a setup would be to turn the piece between centers. For me that means removing my 3 jaw chuck so that I can fit a MT#4 dead center in my spindle.
I don’t know why, but I’ll spend 20 minutes trying to figure out an alternative setup rather than spending 5 minutes removing my 3 jaw chuck.
Then one day at GEARS in Portland someone asked me why I just don’t turn a sacrificial center and use that in my 3 jaw. Great idea!
The principle behind a sacrificial center is simple. It’s a center that can be re-chucked and re-turned to ensure that it’s perfectly centered. Whenever you need to turn between centers you simply chuck the sacrificial center in your 3 jaw chuck, set your compound at 30° (60° included), and shave off a few thousandths to ensure that it’s turning concentric.
It’s simple to build, but since this site is geared toward absolute beginners I’ll include pictures and directions below. The next time you need to turn something between centers, you’ll think twice before removing that chuck!
First, find a piece of scrap steel an inch or so in diameter. Turn a shank down to about a half inch in diameter and at least an inch long.
Part off the piece leaving 2 to 3 inches of length on the larger diameter. The longer you make this portion, the more sacrificial cuts you’ll get out of it before you need to make a new center. Flip and re-chuck the parted-off piece.
Set your compound at 30° (60° included) and cut the center to a point in several passes.
You’re done once your center has a nice point to it.
Whenever you need to turn something between centers, re-chuck your sacrificial center, set your compound at 30° (60° included), and remove a few thousandths to ensure that the center is perfectly concentric along the axis of rotation. That’s it!