Hi guys. I have put my new laser head on this chines 80watt, I put a 2 inch meniscus lense in it and done a ramp test, The best narrowest spot come at around 19mm above work to nozzle, That comes about 2 1/2 inches from where lense is in the tube, I thought i should have about 8-9 mm distance from nozzle to work surface. Is this right or they sent me a 2.5 inch lense.
Did you just pop the new lens into your old set up, or did you set it in the proper place for a 2"? I’m guessing you had a 1.5" lens.
I put it in the new bigger head setup.
It does cut the 5mm wood panels very good now.
I thought having a shorter distance from nozzle to work surface would be better.
I ordered a new meniscus lense for the bigger tube.
The little box said it was a 50.8 fl.
Okay, you have a 1.5" lens, did you get a lens tube capable of holding a 2.5" lens? They sit in different positions in a lens tube. What new head did you get?
Cutting is a combination of factors. The thicker the material, the longer the focal length you want, good air assist down close. If you are sitting that high above the work you’ve lost a large part of your air assist productivity.
Cloudray C Series Head Fit to Focus Lens D18 FL38.1& Dia.20mm FL.50.8/63.5/101.6 mm & Mirror Dia 25mm Replacement Part for CO2 Laser Engrave
this is what i ordered
file:///C:/Users/ronni/OneDrive/Desktop/Amazon.com_%20Cloudray%20C%20Series%20Head%20Fit%20to%20Focus%20Lens%20D18%20FL38.1&%20Dia.20mm%20FL.50.8_63.5_101.6%20mm%20&%20Mirror%20Dia%2025mm%20Replacement%20Part%20for%20CO2%20Laser%20Engrave.html
Do you have another lens of known focal length you can try?
It sounds like they sent you a 2-1/2" lens.
No i don’t
Maybe i can order another one in a couple weeks from another place.
you have any suggestions where i can get another one from.
That’s a good head to buy, I have the lower tube and use it in Russ’ lightweight head. I’ll ask a stupid question, but you do have the 2" lens up into the 2" position and not down on the nozzle, correct? That would be the shelf closest to the end of the tube. In that position you should have around 10 to 12mm tip to work. I don’t like that much space so I put a 3mm spacer ring between the nozzle and lens tube. With the 1mm difference between the 18mm and the 20mm shelf I wind up at roughly 8mm from the nozzle with my work surface.
If you are unsure of the FL: leave the cone off of the lens holder, focus the laser on the material, and measure the distance from the lens to material. There is your focal length.
I have the lense tube that is closest to end of tube. when measured from there 2 inches down it shows the 50.8 mm fl should be abou 8-9 mm from cone to work.
That’s the one you want. Sounds like you have a good handle on what you are doing. Russ likes to keep his tip to work distance down around 3mm, but he works mainly with acrylics. For my Premium MDF, that generates too much of a resin halo around the nozzle tip, so I keep mine up around 8mm from the work. Still have to give them a quick soak in Zep Purple every so often, but not bad. Just do it when I do my rails. Ya gotta love a scrap piece of plastic gutter.
The end of tube that has threads way in. I suppose if i had another ring to th read in it then my menicus up or down to get my fl where i want it to be . Then i could get fl may 8-10mm from small end of cone nozzle. would that work? If so you know where i could get another screw piece that holds the lens in the tube now. it would be like sandwiching it between two screw rings.
Send an email to sales@beambuddy.xyz and I can send you one 
That tube and nozzle will hold anything from an HD to a 4" lens. The compound HD nozzle replaces your current nozzle… A 1.5" sits just on top of the nozzle. The 2" sits up against the short end shoulder, flip it over for the 2.5" up against the long shoulder. Flip it over again and put the 4" DOWN against the long shoulder positioned at the top. The Cloudray web site has a good pick of the 2", 2.5", and the 4" positions. If you add a short extension, you can flip it again and put a 5" in the 2" position but at the top.
if my lens fl is around 2.5 " where would i put it to have 8-10 mm distance from tip to work?
i think they sent me a 2.5 " instead of 2"lens because that is what i am getting best fl at.
Or just order another 2" lens and hope they send me the right one.