# Laser Alignment Tool



## Badge171 (Feb 27, 2015)

Just a thought , But I'm sure you have seen the laser alignment tools for sale for the lathe and milling machine. They do seem like a useful tool and a time saver for 4 jaw alignment (rough in) and loads of other applications. But the pricing is just to crazy for another time saver. BUT. How about my Laser bore sight  for my rifle There about 40.00$ . It woks fine in my tail stock, My Bridgeport keyless chuck , and 5C collets. Anyway seems to work for a initial set up for me
Best Regards


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## cathead (Feb 27, 2015)

I have a magnetic Greenlee level-laser that I use occasionally to indicate
square parts in the lathe.  If you just graze the surface of a square part
or even a round part that you can't for some reason get a dial indicator on,
you can adjust the chuck amazingly accurate.  You could just use a cheap
laser pen and some modeling clay to hold the pen and indicate with that
just as well, maybe even easier than using a magnetic one.  I am going
to have to try it and see how it works.


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## hman (Feb 27, 2015)

I've often wondered about the accuracy/precision of laser alignment tools.  The laser beam *can't* be just a couple thousandths wide ... so how can you get .001" accuracy from it?  In addition, because the old-fashioned type of edge finder is spinning, any runout errors in the chuck or collet tend to cancel out.  I can imagine the consequences of getting a crumb of swarf between the collet and the shaft of a laser unit, and its resulting contribution to inaccuracy.  

What are YOUR results?  I'd dearly love to know!

As far a approximate positioning, there's one neat setup that I plan to build for my mill.  It's shown in a Dan Gelbart video: 



 (starting about 2:15).  Looks versatile and handy!


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## RJSakowski (Feb 27, 2015)

hman said:


> I've often wondered about the accuracy/precision of laser alignment tools.  The laser beam *can't* be just a couple thousandths wide ... so how can you get .001" accuracy from it?  In addition, because the old-fashioned type of edge finder is spinning, any runout errors in the chuck or collet tend to cancel out.  I can imagine the consequences of getting a crumb of swarf between the collet and the shaft of a laser unit, and its resulting contribution to inaccuracy.
> 
> What are YOUR results?  I'd dearly love to know!
> 
> ...


I would agree with you John.   I use an edge finder for x & y locations and find that I can reproduce the location to +/- .0001" consistently.  I have a laser alignment beam on my miter saw and I don't use it for critical cuts because of the beam width and that is where expected accuracy is on the order of .02".   

In addition to the beam width, it is a visual alignment.  All the lasers beams that I have seen have a fuzzy edge to the beam.   The ability of the human eye to  distinguish a beam edge is limited.  Lasers can be focused to sub-micron points but they would have a very short depth of field  As a safety issue, I would be concerned about using a tightly focused laser beam on a reflective surface. 

In the video you posted, runout is not a concern as the spindle is rotating and generating a circle.  Nonetheless, if Mr. Gelbart can locate a center to within a thousandth, he is a better man than me.


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## cathead (Feb 27, 2015)

Badge171 said:


> Just a thought , But I'm sure you have seen the laser alignment tools for sale for the lathe and milling machine. They do seem like a useful tool and a time saver for 4 jaw alignment (rough in) and loads of other applications. But the pricing is just to crazy for another time saver. BUT. How about my Laser bore sight  for my rifle There about 40.00$ . It woks fine in my tail stock, My Bridgeport keyless chuck , and 5C collets. Anyway seems to work for a initial set up for me
> Best Regards




Here is a photo to help explain my centering method.  I set the magnetic laser level on the tool post
and position it so it just grazes the edge of the part.  I don't look at the dot at all, only the grazed part.
It takes several adjustments when you get close so the grazed edge just touches the end of the part.   The
angle of the laser to the part is only several degrees from the lathe axis.   I realize it isn't
the most accurate method but if careful one can get close to .001  inch.   When all four sides graze the
edge the same visually, it's pretty close.  












RJSakowski said:


> I would agree with you John.   I use an edge finder for x & y locations and find that I can reproduce the location to +/- .0001" consistently.  I have a laser alignment beam on my miter saw and I don't use it for critical cuts because of the beam width and that is where expected accuracy is on the order of .02".
> 
> In addition to the beam width, it is a visual alignment.  All the lasers beams that I have seen have a fuzzy edge to the beam.   The ability of the human eye to  distinguish a beam edge is limited.  Lasers can be focused to sub-micron points but they would have a very short depth of field  As a safety issue, I would be concerned about using a tightly focused laser beam on a reflective surface.
> 
> In the video you posted, runout is not a concern as the spindle is rotating and generating a circle.  Nonetheless, if Mr. Gelbart can locate a center to within a thousandth, he is a better man than me.


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## RJSakowski (Feb 27, 2015)

Thanks for the explanation and visual, Cathead.  It is certainly worth an experiment.  Always looking for different ways to skin the cat, no pun intended.


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