[Lab] a few thoughts

Darcy Whyte darcy at siteware.com
Fri Nov 12 18:44:55 EST 2010

Here are a few thoughts about the final stages of building my laser cutter.

1) Laser alignment: I was thinking of mounting the first mirror, then
mounting a block of wood at the location of the 2nd mirror. I can adjust the
first mirror by firing the laser into the block of wood till the dot is
where expected. Then move the block to the next mirror and adjust another
mirror. Eventually the laser will come out of the nozzle.

2) Visible laser: If I want to get a laser pointer and add it as a guide as
to where the laser is about to burn, any suggestions for that? It might be
nice to have a visible dot where cutting is about to begin. Where to get a
good pointer for this? What about other ideas of knowing where the laser
will burn. This is just for doing stuff like finding (0,0,0) and such. An
alternate idea is to have two small pointers attached on the laser cutting
nozzle. They would be angled to reach the focal point. So if the laser is in
focus, the two dots converge and we can see the cutting point. If out of
focus, we see two dots. Another idea might be to have a post coming down and
the laser is a certain offset from that.

3) Stray laser power. The beam starts at about 1mm width. The 50mm focal
length lens will then bring it to a smaller cross section for cutting. It
will obviously diverge at distances over 50mm. I figure it will be back to
1mm width at a distance of 100mm from the lens. At 150mm, it will cover 4
times the area so the power will start to be more spread out. So if the
cutting surface is like 150 or 200mm from the table, then the laser will not
heat the table too much.

4) Cutting table. I'm making a cutting table out of some chicken wire like
stuff I was given. I'm planning on stretching it over a rectangular frame so
that it is nice and flat and rigid. I think that the laser will heat it but
not too much as it's metal. I guess it it wears out quickly I should try
some different material.

5) The laser high voltage terminals stick out of the glass and are about .2"
long. They are about 60 thousands of an inch thick. For testing I used some
thin copper wire to wrap the high voltage wires onto it. I then used
electrical tape and some thick rubber tubing to insulate. For production,
there must be some sort of connector that can slip on the pegs and be okay
with 25,000 volts. Any ideas?
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