In doing research on my laser build I found that a 80w laser is not powerful enough to cut through three quarter inch acrylic. My question is can you cut at a slower speed or do multiple passes to achieve the same result as say a 100w laser.
Tony Wish
In-Tech Systems
CO2 Tube power
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Re: CO2 Tube power
Both, lower speed and multipass (with z-lift after each pass) will work, but what is the focal length of your lens??
For 3/4 inch (19mm) there is one problem: your depth of field is smaller if your laserbeam is wider, as this is the case with higher power tubes (CO2)
With a 3mm bundel (like 25-40W) and a 100mm (4") the DOF is ~ 29mm and a spotsize of ~0,45mm but with a bundle of 7mm ( like your 80W tube) and the same lens the DOF is only ~5.5mm and the spotsize ~ 0.2mm
Kees
For 3/4 inch (19mm) there is one problem: your depth of field is smaller if your laserbeam is wider, as this is the case with higher power tubes (CO2)
With a 3mm bundel (like 25-40W) and a 100mm (4") the DOF is ~ 29mm and a spotsize of ~0,45mm but with a bundle of 7mm ( like your 80W tube) and the same lens the DOF is only ~5.5mm and the spotsize ~ 0.2mm
Kees
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Re: CO2 Tube power
Thank you for the info. I plan on having two lenses, a 50mm and 75mm. When engraving I will use the 50mm and when cutting I will use the 75mm. I still have a question in when I exchange lens do I have to somehow change the distance to the material and the laser head? Also you mentioned when cutting 3/4 inch acrylic in multiple passes to raise the "Z" after each pass. I don't understand the reason. Please explain. I have a large cnc router with plasma attached and am retrofitting a laser to add versatility. Still learning basics on how to properly set up so any help is appreciated.
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Re: CO2 Tube power
Lifting the Z is a trick I use in combination with some electronics. I use the U-axis to lift my table after each job. I doubt that a "normal" machine has these capabilities, you have to create that..
The reason for lifting the table is to set the focuspoint deeper in the material after each pass.
Kees
The reason for lifting the table is to set the focuspoint deeper in the material after each pass.
Kees
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Re: CO2 Tube power
Kees,
Great idea. I suppose I can put this in the g-code somewhere to automatically do this. What is your suggestion as to how much more you would raise the head?
Tony
Great idea. I suppose I can put this in the g-code somewhere to automatically do this. What is your suggestion as to how much more you would raise the head?
Tony
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Re: CO2 Tube power
If your machine works with G-code, it could be that it works that way.. But that depends on your controller..
Many here, have a LightObject controller like the AWC608 or LO-X7 or maybe even an older DF212..
This controllers have a BLOW-signal which can be used for various purposes. This blow-signal is active while a job is running, from the moment you press Start til the job is finished (extending this time is also possible in the software, to let blowers run a number of seconds to retract the last fume)
When you want to use the U-axis to lift the table a given distance. you have to divert the PUL and DIR pulses from the U-axis to the Z-stepperdriver while the BLOW-signal is active. The Z-PUL and DIR from the controller are disconnected at that time..
In the software you can enter how many times you will do the same job, together with the travel-distance for U..
Kees
Many here, have a LightObject controller like the AWC608 or LO-X7 or maybe even an older DF212..
This controllers have a BLOW-signal which can be used for various purposes. This blow-signal is active while a job is running, from the moment you press Start til the job is finished (extending this time is also possible in the software, to let blowers run a number of seconds to retract the last fume)
When you want to use the U-axis to lift the table a given distance. you have to divert the PUL and DIR pulses from the U-axis to the Z-stepperdriver while the BLOW-signal is active. The Z-PUL and DIR from the controller are disconnected at that time..
In the software you can enter how many times you will do the same job, together with the travel-distance for U..
Kees
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Re: CO2 Tube power
Kees,
I just realized my mistake in interpreting your reply. Your table moves to change the Z height. My gantry moves to change Z. So in moving to change focal length you bring the laser point closer to the material after the first cut in 3/4 inch acrylic. Correct?
Tony
I just realized my mistake in interpreting your reply. Your table moves to change the Z height. My gantry moves to change Z. So in moving to change focal length you bring the laser point closer to the material after the first cut in 3/4 inch acrylic. Correct?
Tony
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Re: CO2 Tube power
Yes, after each pass I move the table a little upwards.
Kees
Kees
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