Issues with Cutting - 80w Laser

[Soren Christensen]

Hi guys,

So after a turbulent trip down ordering a chinese laser (had to scrap the first one, since it was defective to any extend) i finally have a decent machine running. However. (there is always a however).

Its supposed to be an 80w laser tube and its an EFR tube.

But as you can see on these 2 pics below, its struggling to cut 3mm plywood and 3mm acrylic, until it gets to a very very low speed. :(

Am I doing something wrong? Im using the focus pieces that came with the machine, which is roughly 8mm.

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Im afraid, that I wont be able to cut anything thicker than 3mm without having to go down to maybe 5mm/s and with full power :(

Any tips and tricks?

[Kev Williams]

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...

[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...

I have testet the alignment and its deadcenter, which is good. Havent checked the lens. Have messaged the seller and hopefully that can make it a bit more clear. :)

Saying low speed is probably my way of saying, that if I need 30mm/s at 70% power for 3mm acrylic, I would need alot lower speed settings with more power for 6mm acrylic :) Not sure if thats understandable?

[Rich Harman]

Saying low speed is probably my way of saying, that if I need 30mm/s at 70% power for 3mm acrylic, I would need alot lower speed settings with more power for 6mm acrylic :) Not sure if thats understandable?

20 - 30mm sec cutting 3mm is not low speed. You have a cut test where you set the lowest speed to 50 mm/sec and the top speed to 500 mm/sec.

Those speeds are engraving speeds, not cutting speeds. 30mm/sec is good, I rarely go faster - in fact I rarely go over 20/mm sec even if I can because my machine cannot take corners so fast without ringing (wiggles).

Yes of course, cutting something twice as thick is going to take roughly twice as long (half the speed).

[Soren Christensen]

20 - 30mm sec cutting 3mm is not low speed. You have a cut test where you set the lowest speed to 50 mm/sec and the top speed to 500 mm/sec.

Those speeds are engraving speeds, not cutting speeds. 30mm/sec is good, I rarely go faster - in fact I rarely go over 20/mm sec even if I can because my machine cannot take corners so fast without ringing (wiggles).

Yes of course, cutting something twice as thick is going to take roughly twice as long (half the speed).

So the machine is working. Its just me, who is expecting too much of it? :)

[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.

[Soren Christensen]

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.

According to the seller the lens is 16.25mm in diameter.

And yes, I haven't been able to find anything in 16.25mm range :(

So I'm guessing an upgrade is needed 🙈

[Kev Williams]

many Universals use a small lens, not sure the actual dia. but 16.25 would be in the ballpark--

[Tony Lenkic]

ASC365.com sells China lenses as small as 12mm, so it is possible that 16.25mm do exist.

[Soren Christensen]

many Universals use a small lens, not sure the actual dia. but 16.25 would be in the ballpark--

I have search high and low. Not been able to find that size anywhere :/ I run into 15/18 or above/below that. Never right at the spot :(
Thats why im considering getting an upgrade for the laserhead to accommodate other size lenses. :)

[Soren Christensen]

ASC365.com sells China lenses as small as 12mm, so it is possible that 16.25mm do exist.

Have searched their website, with no luck :(

[Tony Lenkic]

Did you check on laser accessories second page?
At bottom of first page there are navigating arrows with numbers 1 2 3 in middle. Click on # 2 page than scroll down.

[Soren Christensen]

Did you check on laser accessories second page?
At bottom of first page there are navigating arrows with numbers 1 2 3 in middle. Click on # 2 page than scroll down.

They have 12, 18 and 20mm lenses :)

[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...

Yesterday, I got the lens out and this is what i saw:

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Discoloration and some unidentified marks, that are not on the surface of the lens, because it wont come off with lens cleaner :/

[Kev Williams]

That lens is cracked...

it'll still work okay, but DOES need replacing, kinda like this one ;)
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This lens started collecting guck from smoke which ended up cooking and coking onto the lens.
The carbon just kept getting hotter and discolored the lens until it finally cracked.
I got the carbon off with acetone, the 'heat' halo and crack remains... and yet this lens
still engraves just fine. I keep around just in case ;)

[Soren Christensen]

That lens is cracked...

it'll still work okay, but DOES need replacing, kinda like this one ;)
447670
This lens started collecting guck from smoke which ended up cooking and coking onto the lens.
The carbon just kept getting hotter and discolored the lens until it finally cracked.
I got the carbon off with acetone, the 'heat' halo and crack remains... and yet this lens
still engraves just fine. I keep around just in case ;)

Wow and I thought my lens was in a bad state :D

I have decided to upgrade the laser head, so I ordered the E series set from Cloudray along with a new lens. So for the time being, the laser is sitting dead in the water :(