2.5" / 63.5mm lens would be against the deeper lens shelf with that on the ‘bottom’ side. I don’t remember the focal length that winds up with, but I put a MDF ring between my nozzle and lens tube to get mine down to around 8mm. That is with the curved side up.
If you go to the Cloudray web site and look at the nozzles & lens tube for the C series, you can scroll down to the pics of the C series. The second one shows the various positions of the 2", the 2.5", and the 4".
Thanks Dave. i will look tomorrow and see where i can put it to get in around 10mm between tip and work.
Why are you using a meniscus lens? It’s uncommon in lasers. Lens tubes are designed to use flat surfaces to mate with, and act as a bit of a heat-sink, which is why Plano-convex lenses are the most common. A meniscus lens has a tiny bearing surface and often results in a cracked lens as they heat and cool much more than a Plano.
In my experience, unless the tube is designed to hold one, best not.
Most commercial machines with meniscus lenses use a carrier bonded to the lens which sits flat on the tube.
The new C series lens tubes come with a cushioned retaining ring. Meniscus lens’ are no problem.
Next time I order a new C series lens tube, going to get some extra retaining rings. With the 13mm extension I have and an extra ring, I can put a 5" lens in the C series tube if I want…
I just buy a bunch of extensions, then can build any tube from 1" to 4" (largest I use).
Hello Dave, I changed my lens to other end of tube and now have a fl of about 12mm.
the sent me a 2.5 inch instead of 2 inch. So we got that fixed. Now BO is asking me what am i using a meniscus lens for? The engraving and cutting looks a lot better. Should i change back to a plano lens for a particular reason.
It’s users choice. Somewhere back in the fog I remember Russ doing some experiments with both Plano and Meniscus with mixed results. My only hold back on that is his current research into a long compound lens for cutting thick material. I had thought about ordering some extra lens’ and an extra lens tube, but am going to hold off until he’s done. He gets his lens’ for free, I have to pay for mine.
And Bo is right on the lens tube extensions. You can get a tube you flip around, or you can get extensions. A lot depends on what you have for a lens tube. Since you have the C series, you have everything up to a 4" in your hands. It’s only if you want to go single lens and beyond 4" that you would need something more.
Russ’ bench tests with his test rig indicate that there are a few good combinations possible and stay within the confines of the C series tube. Let’s hope those bench tests are born out by real world tests.
Ok I was just asking if it was some reason i shouldn’t use a meniscus lens.
When you come up with a good compound lens setup please let me know.
I really appreciate you guys helping me out.
Keep an eye on Russ’ videos. He’s teased the last two on the long compound set up. I hope the next one has some real world results.
No, if the tube you have its designed to take a meniscus, you’re all good.
The problem used to be that the bearing area of the tube didn’t offer enough to act as a heat sink for a meniscus, as they were designed for the flat bottom of a Plano.
A meniscus gives less optical aberration, and therefore should give higher light pressure at the focal point = better cutting.
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