[Laser Doctor]

The Laser Doctor has checked in. Looking to answer your laser questions.

[asuratman]

Laser Doctor,
Why a new thread?

[Laser Doctor]

The Doctor pressed the wrong button this morning. Sorry.

[mondo50m]

Newbie question--What is the purpose of the gold on the focus lens? It is pretty much worn off of the focus lens that I have, but it still cuts just fine. Should I be purchasing another one?

Milt

[Laser Doctor]

It's not gold. This is an Anti-Reflection coating that the manufacture puts on both sides of the lens. The lens without the AR coating will reflect 4% of the laser power, 2% each side of the lens or transmit 96% of the laser power. With the coating the laser beam will reflect 1% or transmit 99 % of the power.

[OldEngraver]

In the same vein. Why is it necessary for the mirrors to be gold plated? Some people have cut mirrors from hard disk platters and claim comparable results.

[TurbineJesse]

I'm curious about that as well now. After reading your question, I sought out information about using an old hardrive for mirrors and found this great tutorial: DIY Laser: Get Your CO2 Laser Mirrors for FREE

[mondo50m]

I am using nothing but mirrors made from a hard drive and they work just fine. I have a bunch of them that I have cut out.

Milt

[Laser Doctor]

I never have seen this. But the answer is simple. The mirrored surface is silver plated, not a reflective as true laser coating. This also sometimes appears as gold plate. Also works as a reflector. Seem like a lot of work to me

[mondo50m]

It took me approximately 1 hour to make 9 lenses out of one hard drive. This actually amounts to 19 lenses, as both sides are useable. I used my homemade CNC router to cut out the 20mm discs. 18 mirrors would probably cost over $300, they cost me just one hour of my time. Worth it for me. Oh yes, I also had to make a spacer ring, as the lenses are only about
1mm thick.

Milt

[Danceswithcubes]

Laser Doctor, what would be the gas mix on an 80 watt sealed glass tube laser,

Somthing i have always wonderd ,

And are these tubes under a slight vacuume?

Regards

[Laser Doctor]

The gas mixtures are kept highly secretive. There are numerous combinations depending upon the laser type DC or RF. The base mixture is Co2/N2/He.

The Laser Doctor

[Laser Doctor]

Yes laser tubes are under vacuum, just like a light bulb.

[StePraDal]

LD, whats the preferred glue in thin plywood that makes for easiest cutting. Thanks

[mrbbsc]

Laser Doctor,
I would appreciate any help you can offer. I have a 40 watt DC-KIII laser engraver (made in china). The problem is that all of the sudden I cannot regulate the cutting power with the "current regulation" knob. It will work with the test button. When I try to engrave something the current indicator mostly stays around 4-5 regardless of how much I turn up the current regulator knob. Does this sound familiar?

Thanks,
mrbbsc

[Laser Doctor]

It sounds like the current regulator has stopped working. You basically have the one setting without adjustment with the power control. The test button is just a signal to fire the supply. I assume like a test fire button. I do not have any experience with this Chinese power supplies in general. I have seen them in different application and their quite cheap. I assume you can purchase a new one for little money. Probable your best bet.

[fmederos]

LD, is it feasible that a 150W glass tube CO2 laser with oxygen assist would cut 1mm thick steel sheet-metal? I don't mind stainless steel or aluminium, just steel sheet.
Regards,
Fernando

[Laser Doctor]

Wow, what a great question. I honesty don't have an answer for you. Maybe someone in the community can answer it. Now, I have seen many laser cutters of sheet metal. However, they usually start around 5oo watts to 10 KW with oxygen or air assist. The idea is to get the metal red hot first, in one spot, and then start cutting.

[mrbbsc]

Laser Doctor,
I'm not totally convinced it's a bad current regulator because when holding down the test button and turning up the current regulator knob at the same time the current meter responds accordingly.

mrbbsc

[baksiidaa]

LD, is it feasible that a 150W glass tube CO2 laser with oxygen assist would cut 1mm thick steel sheet-metal? I don't mind stainless steel or aluminium, just steel sheet.
Regards,
Fernando

It looks like G. Weike has a couple systems that can do 2 mm.