Best 2" co2 lenses for cutting wood

[Allan Longson]

The discussion on cheap co2 lenses has been hashed over many times but I am wondering about the best co2 lenses (I did search and didn't really find a specific question or answer on this). I have tried cheap chinese lenses (made in the US and finished in china and from a variety of chinese suppliers) and they are all a case of you get what you pay for. The best lenses I have tried were from Engravers Network, their lenses are much thinner than chinese ones and can cut the material I work with (double sided rimu veneer on a 4mm mdf board) much faster and cleaner (the focal point is much smaller) than any chinese lens I have ever had. I would also rate the Engraver Network lenses better than the OEM's I got from Universal via my local dealer.
So has anyone else out there used lenses from Engravers Network and found anything better or comparative? If not, what was the best CO2 lens you have used?

[Dan Hollis]

The discussion on cheap co2 lenses has been hashed over many times but I am wondering about the best co2 lenses (I did search and didn't really find a specific question or answer on this). I have tried cheap chinese lenses (made in the US and finished in china and from a variety of chinese suppliers) and they are all a case of you get what you pay for. The best lenses I have tried were from Engravers Network, their lenses are much thinner than chinese ones and can cut the material I work with (double sided rimu veneer on a 4mm mdf board) much faster and cleaner (the focal point is much smaller) than any chinese lens I have ever had. I would also rate the Engraver Network lenses better than the OEM's I got from Universal via my local dealer.
So has anyone else out there used lenses from Engravers Network and found anything better or comparative? If not, what was the best CO2 lens you have used?

instead of a different lens, try focusing partway through the material for a more effective cut. after entering the material settings into the ULS control panel, go to manual control and lie about the thickness, tell it 3mm or 2mm.

[Kev Williams]

A few years ago I spent a whole day experimenting with my 40w LS900, trying to get it to cut clear thru 3/4" cast acrylic from one side. In all my tests, which involved several passes at different focus positions, the absolute deepest cut I achieved was with the lens focused dead-to-rights on the surface for all cut passes. Any other focus distances I tried proved counter productive, resulting in more melting and burning, and less overall depth. I'm assuming this is because of the angle of the light beam; if you focus below the surface, then the wider unfocused sides of the beam are being absorbed by the surface of the material. That unfocused light has little if any cutting power, and the focal point's actual power density will now be xx-watts minus watts lost just heating up the materials surface.

That said, I've never tried down-focusing on other or thinner materials, but I've really never needed to, as 80-90% of my laser use is raster work. Lasers are funny animals sometimes, and don't always follow the rules!

[Dave Sheldrake]

RMI, II-VI or Zeiss

[Allan Longson]

instead of a different lens, try focusing partway through the material for a more effective cut. after entering the material settings into the ULS control panel, go to manual control and lie about the thickness, tell it 3mm or 2mm.

It's not an issue of focus, I have optimal focus and vector settings (99% of my work is cutting) after working with this material for the last 6 years, 8 hours a day every day. My final Engravers Network lens is on it's last legs and I either replace with them again or consider something else. The lens makes all the difference in the reliability of the cut in the veneer so for my sanity, output of work and minimal number of rejects it is worth spending a little more for quality. I will have a look at the ones suggested.

[Dan Hollis]

A few years ago I spent a whole day experimenting with my 40w LS900, trying to get it to cut clear thru 3/4" cast acrylic from one side. In all my tests, which involved several passes at different focus positions, the absolute deepest cut I achieved was with the lens focused dead-to-rights on the surface for all cut passes. Any other focus distances I tried proved counter productive, resulting in more melting and burning, and less overall depth. I'm assuming this is because of the angle of the light beam; if you focus below the surface, then the wider unfocused sides of the beam are being absorbed by the surface of the material. That unfocused light has little if any cutting power, and the focal point's actual power density will now be xx-watts minus watts lost just heating up the materials surface.

That said, I've never tried down-focusing on other or thinner materials, but I've really never needed to, as 80-90% of my laser use is raster work. Lasers are funny animals sometimes, and don't always follow the rules!

acrylic is a different beast than say, 12mm plywood. after weeks of extensive testing i determined a 50W ULS got best results focusing about 4mm beneath the surface.

this guy demonstrates better acrylic cutting with his laser when he focuses partway though: https://www.youtube.com/watch?v=pYmT9yIjC4Q

[Dave Sheldrake]

"this guy demonstrates"

Beam drag is the nature of lasers, especially lower powered lasers when they are used to cut material that is beyond it's normal working proficiency, pumping (or exciting) more heat into an edge isn't a good way to get a decent finish, the better way is to use a laser set up properly to cut thick materials and a 50 watt chinese junker is NOT the right tool for 10mm acrylic and even then you get beam drag (I get beam drag on a 7.5kW CO2 when cutting 3mm steel)

It's all to do with focal length, depth of field and raw power and kev's explanation of why is pretty much spot on. The focussed beam of a DC excited laser is NEVER a straight parallel line, it's a gaussian curve where the depth of field is a point +/- in the Z axis where the beam does not exceed 1.4x the smallest diameter of the spot.

Acrylic works as a wave guide when cut with a laser so is an entirely different animal to thick non-acrylic plastics or woods (or even metals)

The single best method to cut thick materials with a laser is to get a long focal length lens with enough raw power to do the job rather than mess around with work arounds that will never prove either reliable or practical in any sense of the words.

[John Noell]

RMI, II-VI or Zeiss

What do you think of Mellor lenses?

[Clark Pace]

I take offense to of china 50watt china machines being junk. I have had minw for years and it has been very reliable. It engraves and cuts fine. More than paid for itself

[Wilbur Harris]

I take offense to of china 50watt china machines being junk. I have had minw for years and it has been very reliable. It engraves and cuts fine. More than paid for itself

Me too Clark...but this and $2.27 will get a cup of coffee in some places. Dave knows what he's talking about and I agree that compared to a Trotec...my laser is junk. I would probably use a different word but....it's just a word. Pretty sure Dave has some of this same junk sitting around somewhere.

[Kev Williams]

lol, he didn't say ALL Chinese 50w machines are junk!

I love my Triumph! Granted, it isn't always the right tool for the job (what Dave was saying ), but when it is you can't beat the bang for the buck. Friday night mine was making me $25 about every 6 minutes. After the 20 piece job is finished, it'll have made more than 10% of it's cost in just under 3-1/2 hours. I've owned it 3 years now, and it's been making pure gravy for about 2-1/2 of them.

[Clark Pace]

lol, he didn't say ALL Chinese 50w machines are junk!

I love my Triumph! Granted, it isn't always the right tool for the job (what Dave was saying ), but when it is you can't beat the bang for the buck. Friday night mine was making me $25 about every 6 minutes. After the 20 piece job is finished, it'll have made more than 10% of it's cost in just under 3-1/2 hours. I've owned it 3 years now, and it's been making pure gravy for about 2-1/2 of them.

I have owned 2 ULS machines myself, and yes they were better than my redsail. I still would not consider my redsail junk. However if all I was doing engraving my ULS would win hands down on speed.

[Bill George]

I think if you purchase Any Chinese machine without doing your research, it could be a work in progress. If your not prepared to or able to do that work then your in trouble. Most problem lasers on here are eBay purchases by people who have no idea what they are getting and no idea of how to fix.

[Bert Kemp]

I made some acrylic tokens for the kids going on the Snowball Express yesterday, and one line of text was less then 1mm high and if I put on 3 pairs of my readers I could read that text no problem. Now I'd say thats pretty good for my Chinese Laser.

[Dave Sheldrake]

What do you think of Mellor lenses?

Apparently very good John although I haven't used them in a laser application myself.