[uspl]

Afternoon all

Through a fortuitous circumstance at work I now have a supply of laser pointers.

Comments appreciated on this idea:

• Strip the laser pointers out of their cases leaving just the laser diode itself
• Mount it in a suitable tube (6mm aluminium comes to mind)
• Feed some power
• Align them on X-Y-Z pointing at a set of light dependent resistors housed behind a shield with say a 0.5mm hole in it.
• Use an Arduino board to monitor the LDR
• Take the output from the Arduino to the BOB

I figure no moving parts and potentialy less "noise" than a mechanical switch.

I am trying to figure a way to use this setup to home the machine as well rather than a touch plate setup. Mount a laser at precisely 50mm above Z zero and use the Mach three offset feature. When the beam is broken, that is the tool tip.

Any thoughts ?

[mike_Kilroy]

what a wonderful idea! plse do it and then report back. I have apps I could use same for! thanks.

[vger]

uspl,

I can see one possible drawback. I'm not sure what kind of machine you have, however, most of them generate flying debris or sawdust or something. If your beam path is long and a chunk of sawdust interrupts the beam, you might get a false limit hit condition. Even the little tiny opto interupters I use on my machine do rarely encounter such an issue and the separation between emitter and detector is only about 1/8 inch.
You might get away with it using the LDRs rather than photodiodes or phototransistors, due to the much slower response time of the LDR.

[uspl]

Hi

The swarf issue is one I am aware of which is why I am looking at this setup for homing only; i.e. when the environment is clean. I looked at my original post and the title and now see my mistake.

For limits I am using these but will persist with the laser idea for homing.

Thanks for looking

[HorridHenry]

I'd say an infared beam was a better option.

[HorridHenry]

Tweakie beat you to it on this one....

I am trying to figure a way to use this setup to home the machine as well rather than a touch plate setup. Mount a laser at precisely 50mm above Z zero and use the Mach three offset feature. When the beam is broken, that is the tool tip.

Tweakie.CNC - Tool Position Setting

[HorridHenry]

Making a digitizing probe....

[ame=http://www.youtube.com/watch?v=KOew0RzdaYE&list=UUzpTlxwNwlOOoE_RK8vtPGw& index=20&feature=plpp_video]RoboCNC Projects 007 : Making a Digitizing Probe / Touch Probe - YouTube[/ame]

[txcncman]

I'd suggest multiple beams/sensors in parallel. The chances of all beams being broken accidentally at one time is astronomical. Unless you drop a piece of material in the zone.

[underthetire]

Sounds like a neat project. You could always sell the laser pointers on eBay and take the money to buy prox switches. Not as fun though, I get it.