[chuck767]

I have a 150-180 W RECI tube that I want to use for cutting cast acrylic and plywood. I would like to cut Acrylic and plywood from 1/8 of an inch to 1/2 inch thick with only one lens.

If this is possible what focal length lens should I use?

Thanks ,
Chuck

[rayscott]

Hello,

I am not sure if your lens is 20mm diameter or otherwise. It doesn't matter a lot.. except that your lens needs to be able to receive the entire laser beam. I would hope your lens is bigger diameter. As the laser tube wattage goes up, the beam diameter is also expected to be larger.

The focal length of the lens is depicted by the curvature of the lens. A 50mm lens will have more curvature than a 76.2mm lens. The actual diameter of the lens could be the same.

Your cutting application would decide what lens you want to use. I think that a 63.5mm Focal Length lens would work just fine for your needs.

I would NOT go to using a 76.2mm lens yet. It is normal that the minimal spot size gets larger as the focal length gets longer... but you need the longer focal length while cutting thicker materials.

Thank You,

Ray Scott - Rabbit Laser USA

[chuck767]

Hello,

I am not sure if your lens is 20mm diameter or otherwise. It doesn't matter a lot.. except that your lens needs to be able to receive the entire laser beam. I would hope your lens is bigger diameter. As the laser tube wattage goes up, the beam diameter is also expected to be larger.

The focal length of the lens is depicted by the curvature of the lens. A 50mm lens will have more curvature than a 76.2mm lens. The actual diameter of the lens could be the same.

Your cutting application would decide what lens you want to use. I think that a 63.5mm Focal Length lens would work just fine for your needs.

I would NOT go to using a 76.2mm lens yet. It is normal that the minimal spot size gets larger as the focal length gets longer... but you need the longer focal length while cutting thicker materials.

Thank You,

Ray Scott - Rabbit Laser USA

Thanks for the input Ray,

My lens holder excepts 20 mm and 25 mm.


I have a 76.2 FL 20 mm lens And a 50.8 FL 25.4 lens

Why would you not recommend the 76.2 mm lens at this time?

Thanks,
Chuck

[rayscott]

Thanks for the input Ray,

My lens holder excepts 20 mm and 25 mm.


I have a 76.2 FL 20 mm lens And a 50.8 FL 25.4 lens

Why would you not recommend the 76.2 mm lens at this time?

Thanks,
Chuck

As I had said, the 63.5mm l me would do just fine for that thickness of materials. The problem of the 76.2mm lens is that the spot size gets larger, thus requiring the laser to cut a wider kerf and attempt to cut deeper. The 63.5mm lens is expected to have a smaller spot size and cut a narrow kerf. By cutting a narrow slot (kerf), there is less material burned away and able to cut much deeper.. same wattage.
I think this all goes into saying that we should try to keep our optics as clean as possible. And purchase the best lenses that we can reasonably afford.

I read that you already have a 76.2mm lens. I would suggest that you try to use it. I also recommend that you go through the alignment and cleaning of all your optics. Make sure that the laser beam does not get obstructed by brackets. ... it always helps to use a laser power meter to test the wattage before you clean... and year again after you have done cleaning and alignment.

Pay attention to the laser beam shape as it exits the air nozzle. You might find that the 76.2mm focus shape does not taper enough to exit the nozzle without being clipped. You might want to purchase a short focal tube extension. Or modify a spare nozzle for this geometry.

Ray Scott