Alignment of mill to hole

[mugabe]

Just read this article "Laser Bore Sight" and got idea for mill to hole alignment using laser:
http://www.homemetalshopclub.org/new...b02.html#Laser

But instead of tuning laser to be alignment with hole center what will be if we add angle between laser ray and spindle ? We get a circle (when spindle rotates) whose diameter will vary dependent on distance from laser head (attached to spindle) to the material with hole to be aligned. Choosing distance from laser (by tuning mill z axis) to get exact hole diameter we can manipulate x and y to place a light circle on hole edge. Then we get hole aligned to mill. Any opinions ? Or did i discover America again ?)

Would be nice to try it on dro equipped mill (which i dont have yet) to get repeatability results.

[ConKbot of Doom]

You would still be relying on your eyes lining up the laser with the edge of the hole...

The indexing system we use at work has a plug that goes into the set points on fixtures, it has a crosshair pattern on it, and a 1/16" or so hole in the center, going about .2" down into the plug. You put the laser in the spindle, and the beam from the laser is actually a line, at a distance, it has a focal point about 6" from the end of the pointer. You move it to that height, and adjust your X and Y, when the laser goes into the hole, the spot dissapears.

Repeatability is probably .003-.005 or so, I would have to estimate. I cant really say for sure, because the Thermwood routers I work with have who knows how much slop and backlash.

If you have a nicely round hole, swinging it with a last word indicator doesnt take that much longer it you would need the precision.

[Zumba]

Lasers for visual use are for weekend dabblers, IMO. They attract the "DIY" crowd to miter saws, drill presses, etc. For milling, they have very questionable accuracy and repeatability.

For indicating a bore, the only tool I'd use is a Blake Co-ax indicator. They're not expensive, and you can get within tenths of center. They beat all dial & test indicators because they're meant to be mounted on rotating spindles... mills for indicating holes, rotary table center bores, etc, and lathes for aligning the tailstock. No need to bend you neck around the spindle as you turn it to see the dial face.

At only $200, most other methods are "expensive" in comparison, considering how much extra time you waste and how inaccurate they are.