An Optical Alignment Tool
by Dick Saunders
After making the optical center punch that was presented in the June/July 2006 issue of Machinist’s Workshop, I got the idea that an optical centering device to align the spindle on the mill, mill-drill, or drill press would be handy. This design allows you to align the spindle to a reference mark on the work, just as you would do with an optical center punch.
My machines have 1/2" chucks on them, so I used a 1/2" shank on the tool; size the tool to fit your machines. A piece of 1" diameter aluminum was used and the shank was turned to 1/2” diameter for 1”. The body was turned just to clean up and polish it nicely. The blank was set in the mill vise at a 35º angle and dialed-in on center. The hole for the plastic eyepiece was drilled and bored for a light press fit.
The eyepiece (made of clear plastic salvaged from a towel rod) was cut to length plus 1/2" and pressed into the body.
The final assembly was placed in the lathe and dialed-in to ensure concentricity. The extending part of the eyepiece was turned off flush to the bottom of the tool. Tool marks on the ends of the eyepiece were removed with 1,500-grit sandpaper and the ends polished with plastic polish and a cotton ball. I used a lathe tool with a very fine point ground on it to cut the cross-lines and a .156” diameter ring to serve as the bull’s-eye.
When using the punch on parts in the milling machine, the center picks up the mark very accurately. It is a lot easier than sticking my head under the spindle.
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