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Laser Center Finder

for Mill or Drill Press

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Locating work on the mill with an edge finder often takes longer than desired, especially when accuracy need only be within a couple thou. A wiggler is a good alternative since it's generally faster to use than an edge finder. Dan Gelbart showed an interesting alternative which is fairly quick to use and accurate to a couple thou, see this video at 2:15. Dan Gelbart has a number of informative videos so check them out while you're there.

An aluminum casting from my scrap box plus a turned shank and a laser pointer from the dollar store was all it took to copy Dan's idea. The mounting shank has 3/8" and 1/2" sections so it fits both of my end mill holders and will also fit into a drill chuck, of course. To mount the laser pointer I milled a hole at 45 degrees such that the laser would intersect the spindle center line 1.25" below the bottom of the casting. The laser pointer is 1/2" diameter so the hole was enlarged by moving +/- 4 thou in X and Y -- this provides a friction fit but a set screw (or glue) could be used if needed. A nylon ring with an ID of 0.530 slides down the pointer to depress the ON button. The shank has a 1/4-20 spigot to fit a hole d/t in the center of the scrap casting - a short piece of aluminum stock would be a suitable substitute for the casting. Lots of latitude is possible when making this - as is often the case, the concept is the hard part... and Dan supplied that ;-)

Dan's video provides a tutorial on using this center finder. I set a 0.625" round vertical in the mill vise and used a Starrett edge finder to locate its center. Based on prior testing, this is accurate to better than 1/2 thou; the DRO was then zeroed for use as the reference. I used the laser center finder to find the center of this pin per Dan Gelbart's instructions - errors were in the range of 1-3 thou, about what was expected. I found that it took some fiddling to get both X and Y right by looking at the slope of the ring the laser traces on the part, something that wasn't obvious to me in the video.

The laser pointer I have is 1mw red and not bright enough to view with the bright lighting I have on my mill so I must temporarily turn the task lights OFF. The eye is more sensitive to green so that would be a better color choice for the laser. A 5mw laser might be a good choice too although safety issues start to occur at this level of laser power. Haven't used it enough to determine battery life.

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