CAD CAM EDM DRO - Yahoo Group Archive

Re: [CAD_CAM_EDM_DRO] High press. or Laser

on 2001-03-14 10:26:42 UTC
Hi Tom,

There are far too many Jo(h)n's on here, we must just be naturally
talented I guess. : )
I'm John, and started this post. In answer to your question yes a laser can
be built at home, or more likely in the shop. It's a VERY realistic goal to
set out to build one. People seem to assume that if you mention the word
Laser it's instantly something space-aged that only guys in white jackets
can even begin to dream about. There are MANY home built CO^2 lasers, in
particular they follow the plans set out first in Sci.-America. This was a
design for a 30watt laser and I'd say have a read of the article (If you
could find it) but it's been improved so much since then it's almost
unrecognisable now. I was on a list for a while and one of the posters was a
17 year old lad who'd built his own, it even looked a lot better than some
I've seeen made by 'professional hoobiests'. Most of them are 30watt tubes
but there a few 100watt ones made as well. There's nothing complicated at
adding 70watts more it's just most people don't need it for burning bits of
paper and things at science fairs. The power requirements for CO^2 lasers
are anything but complicated. I'd trust my little brother, maybe, to do it
from a sheet of instructions. All they need basically is a neon sign
transformer. 30 watt tubes are typically run off 15kv transformers at 120ma
or so. A Variac transformer (Variable) can control the actual output. IR
crystal lasers are used in industry because they're easy to guide and have
emense pulse power, single shot mode, but the crystals bring all sorts of
problems with them. They're quite expensive (ND:YAG is usually a few hundred
for a stuby 3cm long pencil sized rod), break relatively easily and home
made lasers using them will only really operate in single shot (One every
few minutes, continuous operation takes expensive bits). If you wanted to
make one you'd be looking at something like the below (30 watts): -

Optics:
Zinc selenide, transmitting mirror:
£30 - 60
Copper / Aluminium mirror for back: £30 -
50
or, silver / gold mirror on silicon:
£40 - 100
Glass for tube and water jacket:
£20 - 40

Power:
Neon sign tranformer:
£20 - 100
Might even be free, neon sign shops give away ones sometimes
that they have spare.
Variac:
£30 - 60

Vacuum:

20 micron vacuum pump:
£125 - 180
Digital vacuum guage:
£25 - 50
Greases, seals etc:
£20

Gas:

Laser mix CO^2:
£70 - 100
Regulator:
£30 - 70

Extras:

Hosing, metal base, supports etc:
£20 - 40
If you're a machinist you'll most likely already have all
this, plus you could mill some
VERY fancy mirror mounts.

If anything I've over estimated those prices by quite a bit. Most of the
stuff you can pick up second hand or even free, except the optics. You'll
need a ZnSe lens to focus the beam but it's not too bad. Guiding the beam to
cut is really going to rack the cost up. The cheapest way would be to just
mount the tube facing into a moving bed, or to have a single 45degree mirror
over the bed and the laser off to the side. The only other bits you'd need
would be maybe a fan to keep the smoke off your expensive optics. You could
build one for much less then I've said above it just depends how good you
are at finding the bits for free. They're typically 10 - 15% efficient, so
to make you're laser 100watts you'd just need to make the power supply a bit
bigger. Anything too big and you're into water cooled optics and all the
rest. You can add special line filters and bits to it to make it 'special'
but they're not essential. I read running them on DC can achive a much
better efficiency. You can pump them with a tesla coil ro even a really big
microwave tube. I'd suggest normal AC first though. The big capacitors you
mentioned are associated with things like copper halide (Emerald green ,
golden yellow) lasers and also crystal lasers, which use VERY powerful
flashlamps for a pump. The caps. in crystals lasers are typically many times
that in a heart jump set (I can't spell the word). In terms of wat a 100watt
tube will do you need to think about what you're cutting. It's all dependant
on how much of the light at 10.6um IR will be absorbed. Cystal lasers,
ND:YAG (Neodymium: Yttrium Aluminium Garnet) emit 1.06um which you can steer
with fibers. Have a look at
http://www.pemed.com/surgery/lasers/ndyaglsr/ndyag.htm to see one. Alone
CO^2 will weld metal and engrave stone / mineral rocks. To cut you need a
gas to assist it, oxygen for steel and an inert gas like nitrogen for non
ferrous and wood. It's the same as when you use a cutting torch, it's not
the neutral flames that cut but the stream of oxygen pushing the material
away.
I would VERY strongle suggest you have a look at Sams laser site. It's here
at http://www.misty.com/people/don/laserfaq.htm don't be fooled by it's
simple layout. The bits you want to read are the CO^2 laser sections in Part
3 and 4. They are PACKED with info now and loads of pictures, just about
everything you'd need an answer for. You might want to look at the other
lasers as well on that intro page. The nitrogen laser is incredibly simple
and can even pump a dye laser for loads of different colours, no burning
though. : )

Best wishes,
John (Mail me off list if you want, info.host@...)


----- Original Message -----
From: "Tom Eldredge" <harmonyt@...>
To: <CAD_CAM_EDM_DRO@yahoogroups.com>
Sent: Wednesday, March 14, 2001 2:22 PM
Subject: Re: [CAD_CAM_EDM_DRO] High press. or Laser


> Jon, and the other laser experts:
>
> I hope I am not amiss in shortening the thread title, but it really seems
> like you all are now talking about lasers, not high pressure water jet
> cutting anymore.
>
> I have stayed out of this thread because I know nothing about lasers,
except
> some very basic theory.
>
> Can people really put together laser systems in their home shops?
>
> I have heard that the power supply needs are really challenging. Large
> capacitors etc. Can big capacitors be homemade if the physical size of
the
> system is not an important factor?
>
> How much do you think would it cost to be able to do engraving in wood,
or
> build a 50 or 100 watt system like the one you saw, Jon?
>
> Although I love creative machinery, I am not sure I could market the
things
> it could do anyway, but I thought I would ask the above questions anyway.
>
> Tom Eldredge
> ----- Original Message -----
> From: <MIADSGNS@...>
> To: <CAD_CAM_EDM_DRO@yahoogroups.com>
> Sent: Wednesday, March 14, 2001 3:10 AM
> Subject: Re: [CAD_CAM_EDM_DRO] High pressure water jet (Lasers)
>
>
> > I have been part of this CAD CAM group but have missed some of this
> thread.
> > Can someone share an Email of this guy that has been experimenting with
> > lasers?
> >
> > Thanks.
> > Mario
> >
> >
> > [Non-text portions of this message have been removed]
> >
> >
> > Welcome to CAD_CAM_EDM_DRO@...,an unmoderated list for the
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> >
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>
> Welcome to CAD_CAM_EDM_DRO@...,an unmoderated list for the
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>
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Discussion Thread

Tom Eldredge 2001-03-14 09:40:12 UTC Re: [CAD_CAM_EDM_DRO] High press. or Laser e.heritage@b... 2001-03-14 10:26:42 UTC Re: [CAD_CAM_EDM_DRO] High press. or Laser ballendo@y... 2001-03-14 16:18:37 UTC DIY lasers was Re: High press. or Laser stevenew@n... 2001-03-14 17:25:33 UTC Re: High press. or Laser