Issues with Cutting - 80w Laser

[Soren Christensen]

What lens you using, and what do you consider a low speed?

As a reference, my 80w RECI-tube Triumph will cleanly cut thru 1/8 (3mm) acrylic, at 20mm/sec, with a 2" lens, at 26mA.

If you have a cone on the lens, remove it and see what happens. If it cuts better then your beam is hitting the cone

Have you made sure the beam is hitting the mirrors reasonably centered? Any bit of beam missing a mirror is going to drastically reduce the focused beam's power density...

So I got info back from the seller. The lens has a diameter of 16.25mm. Not sure what that translates into in ".

Also, is it possible to upgrade the cone/head, because it seems that they made the laser head into one of those with integrated airflow, which I have been told isnt as good as one that has the airflow on the side?

[Jerome Stanek]

So I got info back from the seller. The lens has a diameter of 16.25mm. Not sure what that translates into in ".

Also, is it possible to upgrade the cone/head, because it seems that they made the laser head into one of those with integrated airflow, which I have been told isnt as good as one that has the airflow on the side?

You don't have to use the air input just mount a nozzle on the side. I like the air through my nose cone as it cools the lens but I nave water and oil traps before it gets to the nozzle one at the compressor one where it branches off at the shop drop and one just before the laser.

[Rich Harman]

So I got info back from the seller. The lens has a diameter of 16.25mm. Not sure what that translates into in ".

Also, is it possible to upgrade the cone/head, because it seems that they made the laser head into one of those with integrated airflow, which I have been told isnt as good as one that has the airflow on the side?

I prefer the airflow on the side, I've never had an issue with the lens getting too hot. My lens stays cleaner now without the cone than before. Somehow the swirling vortex of air inside the cone would draw debris up onto the bottom of the lens.

My upgrade consisted of a 3d printed bracket that holds a length of aluminum tubing that is bent to aim the airflow right at the cut point. Lots of ways to cobble something together if that is what you choose to do. I also cut the cone completely off, it served no purpose other than to block the beam (the cone was intended for use with shorter focal lengths).

There are two dimensions to a lens. The diameter, and the focal length. You need to get the right diameter so that it will fit into your lens holder. The focal length is chosen based upon what kind of operations you are doing.

I think 40mm is the shortest focal length commonly used. 50mm is common too. It makes for a very small spot but the focal depth is very shallow. You need to be spot on with the distance between the lens and the work piece, and the work piece must be very flat. The shorter focal lengths are generally preferred when doing fine engraving.

I use a 65mm lens. It has a forgiving depth of field - which is necessary for cutting large pieces of material that may not be perfectly flat. It also allows plenty of space between the material and the laser head so that I can use 1/2" x 1/2" x 2" neodymium magnets to hold things down without risk of them getting hit.

I might use a 100mm lens when cutting thicker foam but I have found with the right settings, the 65mm lens does a good job at that too.

[Soren Christensen]

I prefer the airflow on the side, I've never had an issue with the lens getting too hot. My lens stays cleaner now without the cone than before. Somehow the swirling vortex of air inside the cone would draw debris up onto the bottom of the lens.

My upgrade consisted of a 3d printed bracket that holds a length of aluminum tubing that is bent to aim the airflow right at the cut point. Lots of ways to cobble something together if that is what you choose to do. I also cut the cone completely off, it served no purpose other than to block the beam (the cone was intended for use with shorter focal lengths).

There are two dimensions to a lens. The diameter, and the focal length. You need to get the right diameter so that it will fit into your lens holder. The focal length is chosen based upon what kind of operations you are doing.

I think 40mm is the shortest focal length commonly used. 50mm is common too. It makes for a very small spot but the focal depth is very shallow. You need to be spot on with the distance between the lens and the work piece, and the work piece must be very flat. The shorter focal lengths are generally preferred when doing fine engraving.

I use a 65mm lens. It has a forgiving depth of field - which is necessary for cutting large pieces of material that may not be perfectly flat. It also allows plenty of space between the material and the laser head so that I can use 1/2" x 1/2" x 2" neodymium magnets to hold things down without risk of them getting hit.

I might use a 100mm lens when cutting thicker foam but I have found with the right settings, the 65mm lens does a good job at that too.

So basically the lens diameter I have, is one of the smaller ones? Seems that it has a Focal length of 50.8mm

Would it be possible to replace the laser head for a new one, which can use bigger diameter lenses?

[Rich Harman]

So basically the lens diameter I have, is one of the smaller ones? Seems that it has a Focal length of 50.8mm

Would it be possible to replace the laser head for a new one, which can use bigger diameter lenses?

Anything is possible. Can't say how much trouble it would be to swap to a different laser head without knowing more details. It would probably require some amount of fabricating on your part.

Are you sure the lens diameter is 16.5mm? That seems awfully small, a quick search turns up 18mm dia. lenses as the smallest that I could easily find.