40W CO2 Laser for $260...?

[Meatball]

I made my 15W portable my enclosing it in an acrylic case with closed loop water cooling on board. It still requires mains power so an extension cord limits your range, but I'd like to test it on a small inverter and a SLA, as it only consumes about 160W of power.

I just haven't worked out a good way of mounting the 100mm FL ZnSe lens in the right spot yet.

PVC tubes work well for mounting the large heavy optics. Only problem is, if the beam ever touches the PVC pipe material - it will instantly release yellow chlorine gas.

 

[Sigurthr]

Righto about the PVC issue though. I have a TC primary coliform that I have been meaning to cut with the laser but have been putting it off for several reasons; not the least of which is the CL2 issue. I'm hoping good ventilation outdoors will suffice. I am also concerned that the DoF (depth of focus) will be insufficient to cut the ~5mm material, given that it is only putting out ~13W or so.

It's a 20mm diameter 100mmFL lens, not 100mm dia, sorry for the confusion. I also need tube mounts, right now the tube is just wedged in between high density foam, which just barely holds it in place inside the acrylic case. I can't seem to find mounts inexpensively though ($30 each is nuts!) and I don't have the tooling it make it myself. If cutting the PVC coliform goes well I may try my hand at freehand cutting HDPE cutting boards into the right shape for a tube mount. It would just be rough cut and I will hand file it in to shape.

The main problem is I didn't make the acrylic case for the laser, it is a reuse of an old flute display case, so it isn't quite long enough to house the 100mm FL lens for collimation (my real goal), as there is only about 50mm or so of room between the end of the tube and the case wall.

If I place the lens against the inside of the case at the aperture it makes a great pinpoint focus 100mm out from the case, which is good for cutting materials and other cool things like making plasma jets out of glass. Doing this also diverges the beam rapidly after the beam waist, so I could toast bread at about a meter out or so.

The idea is to place the lens 100mm out from the OC mirror and achieve low divergence for long distance beam power. I'd like to be able to ignite paper from at least three meters out; we burn all our garbage here (no pickup 30mi from town!) in a steel barrel and it would be pretty awesome to flip a switch and ignite the garbage from inside the house.

I've had major issues with trapped air inside the closed loop cooling system, but I finally purged enough of the air that it no longer stalls the water pump when air builds up in one spot then gets pumped through. It was an absolute nightmare to close the water cooling loop as air collected inside the pump as well as the heat exchanger. Luckily the waste heat for such a low power tube is so minimal that even poor water flow is more than enough to prevent thermal runaway and keep the tube happily cooled. Sometimes I wonder if I couldn't just fill the tube with water and seal it up with no active cooling.... I'm sure I could get at least 10min of run time before the water even reaches 120F.

 

[IsaacT]

Sigurther you are seriously the most welled versed in random stuff! Everytime I turn around you are mentioning how you are doing something else that sounds complicated but awesome! Mind if I ask what your profession is?

 

[Things]

As long as you keep the chlorine gas away from yourself and anything metal, you should be safe, so yeah, outside would be good.

A good way to make simple CO2 tube mounts is simply a triangle shaped stand, then use rubber bands stretched over the tube to hold it onto the mount. This means you don't have to get a perfect hole for the tube, and don't risk cracking it from clamping.

 

[IsaacT]

Lazerbeak your Link got shot down haha!

 

[Sigurthr]

Sigurther you are seriously the most welled versed in random stuff! Everytime I turn around you are mentioning how you are doing something else that sounds complicated but awesome! Mind if I ask what your profession is?

Haha, why thank you! I don't mind at all, I was a precision TIG Welder and metalworker until economic downturn and health issues (Addison's Disease) caught up with me. Most recently I stocked shelves at Walmart before my disease debilitated me further and then a knee injury crippled me. These days I am unemployed, still recovering from knee surgery.

I consider myself a bit of a modern renaissance man; physics, chemistry, engineering, music, philosophy, archery, forestry, botany, medicine, etc. If it piques my interest or curiosity I pour myself all in (to the limit of my time and finances) until my thirst is quenched and my hunger satieted.

As long as you keep the chlorine gas away from yourself and anything metal, you should be safe, so yeah, outside would be good.

A good way to make simple CO2 tube mounts is simply a triangle shaped stand, then use rubber bands stretched over the tube to hold it onto the mount. This means you don't have to get a perfect hole for the tube, and don't risk cracking it from clamping.

That is quite a lot simpler than the circular cuts I was thinking of, great idea! I've worked around corrosive gasses before (albeit nothing as extreme as Cl or F (I consider iodine and bromine to be quite mild)) but that was always in a fume hood or near an extractor, and I wasn't trying to hand cut in close quarters with an invisible heat ray, haha, so I worry of backdrafts blowing the Cl2 back at the expensive ZnSe lens while I'm preoccupied with protecting myself from the more present dangers. If I can get the beam waist at the right spot and get everything properly aligned and guided for good cutting I'll be quite happy.

 

[Things]

10cm focal length is pretty decent, though you could simply stick a fan between the CO2 laser beside the lens to make sure the gas stays away. Alternatively do it on a windy day

Not the best pic showing the setup, but I simply cut some silicone tubing in half and used that to hold the tube down, though it did start to tear. Rubber bands are sufficient;

 

[Lazerbeak]

Lazerbeak your Link got shot down haha!

Nooooo! What link?

~ LB

 

[trussmonkey25]

I use my 60 watt for deep engraving hard wood in free form. I simply put old shop vac blowing down on laser head to desperse the smoke. and aid in cutting. I'm just using right angle mirror aimed down like a drill press. a drywall bucket and pond pump for cooling system.. if i want it portable i gues wheels on my work bench will do

 

[Spooky]

~ LB

The nice lady in the picture is about to burn her room down the output coupler is the other end looks to be an 80 watt Tongli tube.

On a serious note, on homebuilds make sure you have a bonding strap (path to earth) close to the HV connection, when tubes go they usually arc to the machine chassis. 20Ma @ 25Kv is nasty on a 40 watt, 40Ma @ 40Kv on a 150 watt can ruin your entire weekend.

best wishes

Dave