Re: [CAD_CAM_EDM_DRO] CNC LASER ENGRAVER
Posted by
johnhe
on 2001-10-25 13:38:01 UTC
You didn't mention what it is you're planning to engrave. It is possible to
build such an engraver. Have a look at this site:
http://www.jetstuff.com/rconway/xy.htm
I don't know this guy or have one of his tables but it's an idea of how one
would look. And here's the kind of laser you'd use to power one:
http://www.jetstuff.com/rconway/laser.htm
Making the beam focusable wouldn't be difficult at all. It's not amazingly
clear on that guys table but what is happening is:
1.) The laser is mounted off the table along the axis of one of the
supports.
2.) The laser beam shoots down along the top of this support not spreading
or converging (And it should definitely be covered over)
3.) On the bearing that is going up and down along the axis is a 45 degree
mirror that reflects the beam along the new axis. So no matter where the
bearing is down the support the beam will always go off at 90 degrees along
the next axis.
4.) The beam hits another mirror that is on the bearing that supports the Z
axis which channels it down a tube to the work and through and converging
lens. I'm not overly sure but it might be a condenser that converges the
beam then spreads it back to being parallel.
To make the table cut you need to blow gas into it where it meets with the
beam. The gas depends on what you're cutting. The laser tube itself is never
going to work like a commercial one will 24/7 all year round. It will cost
roughly a couple of thousand, $1k - $2k, for all the mirrors, a new vacuum
pump, your gas and the rest but you'll make a really nice laser with that
much. 100w is roughly enough to start some serious work with. The more the
better. All the optics on that guys table should be covered. It isn't being
over careful, IR laser beams are invisible and do damage instantly. If dust
or vapours start building up on the optics, as soon as the beam hits it,
it'll just muck up the mirrors (And they're expensive). The table is not too
much unlike a router or plasma one. The laser works like so:
A quartz tube is put inside another tube to create a water jacket.
Electrical connections are made at either end of the inner tube. The inner
tube is sealed and filled with CO2 gas, or better, laser mix CO2. A high
voltage is supplied over the ends of the tube with a neon sign transformer
or two depending on the wattage you need. On the ends of the inner tube are
mirrors. One is highly reflective and the other almost completely reflective
to IR. The inner tube, the discharge tube, is connected to a vacuum pump and
a ~10-20micron vacuum pulled. The low pressure and high voltage makes the
gas turn into a plasma. The gas begins to emit photons on the IR wave length
which shoot both ways out the tube. When they strike the highly IR
reflective mirror, silver plated / copper plated / gold plated etc, they
almost all bounce back and move the other way. Gold being the most commonly
used HR mirror. At the other end the 98 - 99% reflective mirror, made from
zinc selenide, lets some of the radiation escape as a beam. The rest is
bounced back to help energise other gas molecules. If you didn't do this the
laser just wouldn't work because the CO2 needs lots of energy to keep it
lasing. There are some gases, like nitrogen, that have huge amount of gain
and will lase in one pass meaning they don't even need mirrors. The CO2
laser is called resonator because the IR resonates back and forth along the
tube. The water jacket keeps it cool. The mirrors are roughly £40 - 50 a
piece and then you need a lens to focus the beam down to a usable size. This
is a really simple explanation. On www.google.com do searches for things
like Sam's laser FAQ and Sam's CO2 laser. Sam has a site that will tell you
just about _everything_ you'll need to know about homebuilt lasers. It's a
really, really good read if you like that kind of thing.
John H.
build such an engraver. Have a look at this site:
http://www.jetstuff.com/rconway/xy.htm
I don't know this guy or have one of his tables but it's an idea of how one
would look. And here's the kind of laser you'd use to power one:
http://www.jetstuff.com/rconway/laser.htm
Making the beam focusable wouldn't be difficult at all. It's not amazingly
clear on that guys table but what is happening is:
1.) The laser is mounted off the table along the axis of one of the
supports.
2.) The laser beam shoots down along the top of this support not spreading
or converging (And it should definitely be covered over)
3.) On the bearing that is going up and down along the axis is a 45 degree
mirror that reflects the beam along the new axis. So no matter where the
bearing is down the support the beam will always go off at 90 degrees along
the next axis.
4.) The beam hits another mirror that is on the bearing that supports the Z
axis which channels it down a tube to the work and through and converging
lens. I'm not overly sure but it might be a condenser that converges the
beam then spreads it back to being parallel.
To make the table cut you need to blow gas into it where it meets with the
beam. The gas depends on what you're cutting. The laser tube itself is never
going to work like a commercial one will 24/7 all year round. It will cost
roughly a couple of thousand, $1k - $2k, for all the mirrors, a new vacuum
pump, your gas and the rest but you'll make a really nice laser with that
much. 100w is roughly enough to start some serious work with. The more the
better. All the optics on that guys table should be covered. It isn't being
over careful, IR laser beams are invisible and do damage instantly. If dust
or vapours start building up on the optics, as soon as the beam hits it,
it'll just muck up the mirrors (And they're expensive). The table is not too
much unlike a router or plasma one. The laser works like so:
A quartz tube is put inside another tube to create a water jacket.
Electrical connections are made at either end of the inner tube. The inner
tube is sealed and filled with CO2 gas, or better, laser mix CO2. A high
voltage is supplied over the ends of the tube with a neon sign transformer
or two depending on the wattage you need. On the ends of the inner tube are
mirrors. One is highly reflective and the other almost completely reflective
to IR. The inner tube, the discharge tube, is connected to a vacuum pump and
a ~10-20micron vacuum pulled. The low pressure and high voltage makes the
gas turn into a plasma. The gas begins to emit photons on the IR wave length
which shoot both ways out the tube. When they strike the highly IR
reflective mirror, silver plated / copper plated / gold plated etc, they
almost all bounce back and move the other way. Gold being the most commonly
used HR mirror. At the other end the 98 - 99% reflective mirror, made from
zinc selenide, lets some of the radiation escape as a beam. The rest is
bounced back to help energise other gas molecules. If you didn't do this the
laser just wouldn't work because the CO2 needs lots of energy to keep it
lasing. There are some gases, like nitrogen, that have huge amount of gain
and will lase in one pass meaning they don't even need mirrors. The CO2
laser is called resonator because the IR resonates back and forth along the
tube. The water jacket keeps it cool. The mirrors are roughly £40 - 50 a
piece and then you need a lens to focus the beam down to a usable size. This
is a really simple explanation. On www.google.com do searches for things
like Sam's laser FAQ and Sam's CO2 laser. Sam has a site that will tell you
just about _everything_ you'll need to know about homebuilt lasers. It's a
really, really good read if you like that kind of thing.
John H.
> Gentlemen,LASER
>
> I am wondering if any of you have had experience with an amatuer built
> engraving machine capable of marking metals to a depth of say .002" or so?am
> I know almost nothing about LASERs and only a bit about this CNC thing I
> exploring at the moment. Possibly a flat bed for X and Y and a manual
> focusing distance adjustment for Z???
> PJH
>
>
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Discussion Thread
P. J. Hicks
2001-10-25 12:45:13 UTC
CNC LASER ENGRAVER
johnhe
2001-10-25 13:38:01 UTC
Re: [CAD_CAM_EDM_DRO] CNC LASER ENGRAVER
Rose, Gary
2001-10-26 11:13:32 UTC
Re: CNC LASER ENGRAVER
zsradding@b...
2001-10-26 12:18:53 UTC
Re: CNC LASER ENGRAVER
Jon Elson
2001-10-26 23:28:17 UTC
Re: [CAD_CAM_EDM_DRO] Re: CNC LASER ENGRAVER