Trotec Lens Replacement

[mike wallis]

Hello,
Is there a goto place (Other than Trotec) to purchase a quality replacement lens for a Trotec Speedy 300 (100 watt)? From what I can tell it's a standard 2" lens. I see some on ebay but not sure if there a quality lens. Any input is greatly appreciated.

Mike

[Kev Williams]

I've bought a crapload of Chinese lenses, they work okay but I've had issues with them making Cermark black, and most aren't very scratch resistant...

Many here will tell you II-VI lenses are very nice, and I've heard some mfr's use them. I bought one for my LS100 off Ebay about a month ago, came from China so I was wondering... But once installed, the Cermark issue I had (wouldn't go black, only medium-dark gray) totally vanished. Nice, black Cermarking now, and all other engraving is still good. What I don't know yet is longevity, but for $38 it's half the cost of a sheet of Romark so I'm not all that worried :)

[Gary Hair]

II-VI are what come with it and what Trotec sells. I bought a couple on eBay and they seem to be legit and are a fraction of the price from Trotec. You might be able to find the holders on eBay as well, again, at a fraction of the price from Trotec. There is definitely a difference between them and the cheapo lenses Kev mentioned from China.

[mike wallis]

Thank for the replies. Defiantly would want to go with the higher quality II-VI lens. I think I found a replacement for the 2" lens on ebay (Chinese) - II-VI CO2 ZnSe Focus Lens Dia. - 19.05mm FL50.8mm for CO2 Laser Head - USA CVD ZnSe. Does this one look to be the replacement for the Trotec Speedy 300?

[Gary Hair]

That's got the right specs so it should be the one you want.

[Kev Williams]

sounds like the exact same lens I got for my LS100--
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[mike wallis]

That's got the right specs so it should be the one you want.

Thank you Gary, got it ordered.

[Joe Adams]

How is this working out for you?

I just figured out the lens on my second hand Trotec Speedy 300/80 is damaged when I removed it to clean before using for the first time. Basically, the coating is gone in the center.

Trotec send me a quote for a new 2.0" lens at $395 plus tax plus shipping. I almost fell out of my chair!

Is the Trotec lens worth the money or are there comparable replacements from other makers.

I'm a complete newbie.

Thanks!

Joe

[Steve Utick]

I've heard a lot of good things about American Photonics lenses. Made here in the USA as well. Give them a call, they should be able to assist you.

[Joe Adams]

I've heard a lot of good things about American Photonics lenses. Made here in the USA as well. Give them a call, they should be able to assist you.

Thanks for the referral. I will check them out.

I definitely want a high quality lens. I am not looking for the "Harbor Freight" version.

The case for the lens that came with my machine is marked II-VI Infrared and was made in USA.

Is this the lens that would have originally come from Trotec or is it a replacement? Do they sell directly or only through Trotec?

Remember, I am the second owner of this Speedy 300 and just trying to learn the ropes.

I want to do things the right way and appreciate the knowledge of this group.

Any other suggestions?

Thanks!

Joe

[Mike Null]

Joe
Buy the II-VI. It's what Trotec uses. BTW, in 23 years I've never had to replace a lens. Keep them clean and they'll last forever.

[Joe Adams]

BTW, in 23 years I've never had to replace a lens. Keep them clean and they'll last forever.

Yeah, I should have checked it at the time of purchase. Rookie mistake. I found it after getting it home and going through the machine prior to my first use.

The coating is pretty much gone from the center of the lens. I'm not sure what would have caused it. Trotec support recommended replacing it sooner rather than later.

Two of the mirrors are pristine but the one in the laser head has a few tiny spots that won't clean off with optical cleaner and lens cloths. I'm not sure if I need to replace it, too. Any thoughts?

[Mike Null]

I would replace it. I believe you can get them from II-VI.

[Joe Adams]

Any advice on where to purchase a replacement II-VI lens other than through Trotec?

I checked the manufacturer's website and couldn't find it.

It's supposed to be a 2.0 inch lens but the focal length on the box (76.2mm) is 3.0 inches. Weird, huh???

You can see the damage.

Thanks!

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[Kev Williams]

Just my opinion here, but it's been my experience that
(a) Unless you're engraving money printing plates or some other type ultra-high precision things with these types of lasers, pristine lenses simply aren't needed, and
(b) These types of lasers can't engrave money printing plates or ultra-high precision things anyway... ;)

My opinions are based on the following--

This is the first laser I ever owned, it's a 1997 25w New Hermes Optima, which is a re-branded Universal. I bought this machine in 2001...
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This the original lens, it was-- and still IS the only lens this machine has ever had.
This photo was taken in 2014, about a year before I sold it to my BIL...
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Note the coating is in horrible condition, and it can only be worse 6 years later...
My BIL uses this machine daily to engrave wood boxes (pet urns) and small 3/8" x 1.5" nameplates for the boxes.
This machine's engraving quality is still at least equal to any of my other machine's, despite this lens :)

If that's not enough, here's a side by side engraving comparison of 2 of my 80w Triumph lenses...
Obviously the one on the right isn't in very good condtion, the one on the left is well used,
but is minus the cracks and halo's of the right lens. The halo was caused by plastic smoke being
fused to the lens during some long Rowmark cutting runs, until a wad of black crust was created,
which overheated the lens and cracked it. I was able to clean off the crust with acetone, which
revealed the halo...

439031
--so one day for fun I decided to see what, if any, difference could be seen with the engraving
quality between a reasonably optically clean lens, and one with 3 cracks and a 2-colored halo... ;)
--to be honest, I was expecting a noticeable difference...

Each of these were engraved with a different lens...
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-- enlarge this pic and examine both engravings.
Personally, I can't discern any obvious difference between the two. I was expecting at least
a LITTLE stray engraving caused by the cracks bending the beam. But I don't see any.
They look pretty much like the same lens did both. And I'm not even sure which
lens did which engraving! And considering this is .07" / 1.78mm high engraving
done with a cheap Chinese 1300x900mm cutting machine, I'm more than a little surprised
at how well a broken lens worked...

Lately I've been buying different lenses to experiment with, in particular I've gotten
a couple of plano/convex to test against the mostly meniscus lenses I have. The plano's are
supposed to be someone inferior to the meniscus lenses, but so far, I can't tell any difference...

In summary, I'll say that it's highly likely I'LL never spend big bucks on a lens.
I'd probably just break it anyway like I did with the only II-VI lens I own ;)

[Joe Adams]

I wanted to thank everyone for their advice and document what I ended up doing.

As stated earlier, Trotec quoted $395 + tax + shipping on a replacement 2" lens for my Speedy 300.

I checked with II-VI and they will sell me the lens directly for $227. They are now made in the "Pacific Rim".

Bruce Sunderland at Design Research Optics was highly recommended by another source. I spoke with him and was very impressed. He makes all his products in the USA. I ended up purchasing a mounted lens from him for $125 that meets or exceeds all the specs of the OEM lens.

This is his website. https://www.designresearchoptics.com/

Thanks!

Joe

[Joe Adams]

One last question, please!

The new lens came in and looks great (to my untrained eye).

Do I need to verify that my focusing tool is set correctly for the replacement lens? Both the existing II-VI and new Design Research Optics are the same focal length (2.0").

If so, how do you go about determining the correct focal distance?

Thanks!

Joe

[Kev Williams]

a ramp test-- I USED to use a long ramp with about an inch of tilt, then used the center of the best-engraved area as my focus point. But not long ago I was holding some aluminum next to the fiber lens to block the beam, I was holding it nearly straight up, and noticed the beam just barely blipped a spot on the aluminum when it came into focus, so I did steep-ramp tests on my fibers, and on my C02 GCC Explorer. I found that this way is much more accurate, especially with the GCC, I found the best focus to be about .040" closer to the work--

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This drawing should help- In the GCC I stood up a 3" piece of scrap just so it would barely clear the bottom of the lens holder. The sweep is only about an inch. Ran it at about half the power I normally run, and it only marked a tiny portion of the scrap. I started trimming a small piece romark until it fit the space between the edge of the lens holder and the mark. Been using this machine for several years now, and since I found the new focus distance the results are noticeable, especially with Cermark.

And it's a good idea to ramp test all lenses, I have two Ga-As lenses that are 2", and the focus distance is about 1/16" closer than my other 2"ers...

[Mike Null]

I agree with Kev but you might get lucky and find that your focus tool works well with your new lens.

I am including a pattern for focus tools. You may have to tweak the length a little to get perfection. Once you find it, make a couple extra ones.

439480

[David Zaret]

i have a trotec speedy 400. when you guys bought these lenses from third-parties, they don't come in the holders, right? how did you manage that? did you buy a new holder, or somehow swap the lenses in the trotec lens holder? thanks.

--- dz

[Joe Adams]

i have a trotec speedy 400. when you guys bought these lenses from third-parties, they don't come in the holders, right? how did you manage that? did you buy a new holder, or somehow swap the lenses in the trotec lens holder? thanks.--- dz

I had Bruce at Design Research Optics mount mine in a new lens holder. I think it was $20 or so more than just the lens. His mounts are machined aluminum but not "color code" anodized or marked for focal distance like OEM lenses. That wasn't a big deal to me.

My understanding of replacing a lens in your existing mount involves popping (or breaking) it out, cleaning up the mating surface, and gluing in the new lens with gel superglue. I am a total newbie so there may be an easier way. For me, the easier way was to buy a mounted lens.