Re: CNC gantry mounted laser questions

> What types are there?.

CO2 sealed and flowing gas
Yag
Others probably, CO2 is most likely what you want.

> Which are the most economical?

CO2 is going to be cheaper but will only cut steel (not sure about
YAG), you need a lot of power to cut aluminium etc. A sealed unit
will be cheaper to run a flowing gas may be cheaper to buy but needs
gas and regulators etc.

> Which are the most durable/reliable?

A sealed CO2 laser has a shelf life, after a while the levels of CO
rise and the power drops however they should be very reliable.
Synrad do some lasers with working lifes of 45,000 hrs so if you
were to get one of those, even used it might last a rather long time
and only needs a DC supply and I think for the larger ones water
cooling. Flowing gas ones should last and last as far as I know.

> What are some good sources for possible surplus units?

Ebay, find the laser you would buy if you could afford it,
Synrad/Coherent for example and add them to your favorite searches.
Perhaps check out distributers and repair/service places for used or
ex-demo stuff.

> What are the safety concerns?

CO2 lasers produce light at 10.6um, this is a very long wavelength
and most things block it. Normal plastic safety goggles can be worn
but some form or barrier is probably a good idea anyway. Cut
materials can produce nasty gases so extraction might be a good
idea. When you cut steel you use oxygen as an assist gas, I suppose
large amounts of oxygen in a room is not the best of things. CO2
lasers do however seem to be about as safe as it comes in high power
lasers, the eye doesn't even focus the light however that just means
only the front of your eyes get burnt!

>
> Which require the least amount of maintenence?
>

Sealed CO2 needs no maintaince until a refill is required. Not sure
about flowing, they don't go off or anything.

> Which are the most efficient?

Pass but ot sure why you care.

I am also trying to build a laser cutter but at a lower power for
non metalic materials, I am not an expert so my advice is a bit
patchy. For laser specific stuff go to the google group alt.lasers
for general CO2 laser cutting "CO2 laser cutting" by John Powell is
excellent.

Graham

eexgs at nottingham.ac.uk (edit email as required)