# Laser center finder. (drill press & mill)



## blujeenz (1/1/17)

I was researching a method of boring a 18mm dia hole in a block of resin using a mill and happened upon a laser center finder on Gadgetbuilders site.
http://www.gadgetbuilder.com/LaserCenterFinder.html
My ears perked up at the mention of "_for mill and drill press_" as I have been in the situation where you need to drill a hole centered on a block and expect to have many more instances in the future.
After watching the Dan Gelbart video regarding its uses, I had a new task on the No1 spot on my DIY list.

Dan Gelbart's prototyping, fast forward to 2:20, when he starts discussing the center finder.


I used a 8mm steel bar from an old printer, nice thing is that it has threaded ends and presence of mind at the time meant that I attached the screws once I had removed the bars. 
The bar has a 4.7mm dia shoulder at each end which worked out well, a 8mm hole in the top of a 25mm sq tube with a 4.5mm hole in the bottom and a 10cm length of bar had a new purpose in my garage.
A small cheap red 1mw laser pointer was mounted at an angle and cable tied temporarily to prevent it sliding out under centrifugal forces. A bit of bent perspex holds the switch on in use.




The cutouts and angled end were to try and balance out the mild vibration, it initially occurred at 1000 rpm and afterwards it was noticable at 2200 rpm, bearing in mind the full circle is visible at 800 rpm, which is probably a good working speed.

I used Q-bond with the metal grey filler powder to lock things in place, top and bottom on the screw.





It works well in practice, as can be seen on this scrap block, the open circle is obviously due to shutter speed in low light.



Its easy enough getting a bar or cylinder centered, make sure the V's near the edge are equal left and right.



In the drill press, my focal point is about 10cm below the laser due to me using a 70 degree angle mount instead of 45 degrees.
I figured the steeper angle would mean less tendency of the laser to climb out of the mounting due to centrifugal forces and as an added bonus, the rate of change of the circles diameter is more gradual (finer control) when moving the quill up and down than it would have been with a 45 degree mount.



The red laser is very dim on certain materials and a green laser would be better, although I dont think they make them in this size.
Anyhow, Im in the market for a new cheapie laser pointer as this one has real shoddy plastic threads which have stripped already, as they say _"buy cheap, buy twice".
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Final version which is also a red 1mw R25 cheapie from the Crazy store, made permanent with CA glue and metal grey powder filler.
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CA'd top and bottom.
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Reactions: Like 3 | Winner 1 | Informative 1


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## Silver (1/1/17)

Wow @blujeenz !
That is just fabulous
Is this to help you find the centre of something?
Sorry for a dumb question, but cant you just measure the item and mark on it where you want to drill?
Or is it that the laser keeps the spot marked while you are drilling?

Reactions: Thanks 1


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## blujeenz (1/1/17)

Silver said:


> Wow @blujeenz !
> That is just fabulous
> Is this to help you find the centre of something?
> Sorry for a dumb question, but cant you just measure the item and mark on it where you want to drill?
> Or is it that the laser keeps the spot marked while you are drilling?


Thanks.
Yip, center of everything on the drill or mill.
You can just measure and drill, but its more work sizing a block and then dividing 27.73mm in half, punching a mark and positioning it on the table.
Marking the center of a rod is trickier, as is the tip of a 5mm dia rod for drilling length wise.
Of course some things cant be marked, like the center of a hole and no, its not a machinists zen problem. 

Say for example you need to need to drill a 10mm dia hole wider to 16mm, then you would need to position the drill bit exactly centered above the original 10mm hole, not something you can mark with a red fineliner. 
This laser centering will also help on the mill, where the table can be moved in the X & Y directions after the work piece is clamped, when boring out an existing 13mm dia hole to 50mm. Pick up the edges of the hole with the laser circle and you can be confident the finished 50mm bored hole will be centered with respect to the original 13mm hole.

Reactions: Informative 1


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## Silver (1/1/17)

Thanks for explaining that @blujeenz 
I understand what you are saying but since I dont work with all the stuff you do I probably dont appreciate the practicalities.
Fascinating nonetheless.

Hope you find your better quality laser!

Reactions: Like 1


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