APMM Community Forum : Laser Cutting
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 Subject : Re:Re:Reducing Laser Pulses on Universal Laser.. 05/06/2019 11:02:28 AM 
Ernest Ang
Posts: 22
Location
Hi Rick, Panos and Charles,

Thank you so much for all your feedback and suggestions!

In the end, we went with using our older Universal Laser that just had the bearing, pulley, coupler, and belt replaced. It definitely has fewer laser pulses and has a cleaner cut compared to our newer Universal Laser that has parts that are more worn out. In addition to that, we use a 0.125" acrylic (or 0.1" chipboard) as a slave plate that we had previously offset the cutline in and out as a jig to place under the material. By doing so, the material is raised 0.125" higher than the honeycomb with an air gap on all the cutlines. The laser cutter will then be cutting through the 0.125" air gap between the material and honeycomb instead of laser cutting when having the material sitting on the honeycomb. The final part will also be supported by the 0.125" acrylic that has the cutlines offset inwards so that they are always being supported during the laser cutting process. We found out that by doing so we reduced the laser pulses significantly and hardly see any pulses at all in the end.

There are just so many variables that could affect the pulses but we found that this is the solution that works best for us, hopefully you will find this solution helpful for you as well.
 Subject : Re:Reducing Laser Pulses on Universal Laser.. 05/05/2019 02:48:07 AM 
Rick Montzka
Posts: 3
Location
Wish I could be of more help on this one, but I have a similar problem. I too have tried many settings in the Universal Laser Driver in my quest to cut 1/4" Baltic birch plywood. I've replaced the laser cartridge twice this year and have the technician doubting his watt-meter and questioning my material. I've had some luck slowing down the speed (in percent) of my cuts. This eventually does cut through, but it leaves the edges sooty and black. (I miss the nice brown edges I used to get.) The technician looked over my lens and mirror and said they were "cleaner than clean". Likewise, he adjusted the mirror at the end of the X-axis to make sure the laser was going through the center of the lens. The only thing I have done different is order Baltic birch in 4' by 8' sheets instead of 5' by 5' sheets. Perhaps it is the glue or the inner plies causing my trouble.

For your problem, this might be somewhat of a long-shot, but does your computer driving the laser have a screen saver? Perhaps the marks occur when Windows decides it's time to do something like engage the screen saver and the laser has to wait for the next batch of commands. That might produce random marks on your cuts. I'm not exactly sure how to tell Windows to "pay attention to the laser cutter only" or "stop trying to update yourself". Perhaps the next time you run the job, just unplug the Ethernet cable and disable the screen saver. Those two actions would prevent your computer from "contacting the mothership" and performing counting operations that result in shutting down hardware. I'm no expert in this area, and it would be a total long-shot, but something else you could try.
 Subject : Re:Reducing Laser Pulses on Universal Laser.. 03/15/2019 02:27:10 PM 
Panos Fiorentinos
Posts: 1
Location
Was wondering the same thing with my laser and asked Universal rep.
Their response was something to do with electricity maybe the use another
outlet or power supply. It was awhile ago and I’ve just grown to love with it.
Have contacted Universal head quarters?
 Subject : Re:Reducing Laser Pulses on Universal Laser.. 03/15/2019 01:22:04 PM 
Charles Overy
Posts: 25
Location
Ernest,

I don't think that those artifacts have anything to do with the PPI setting. I think they have to do with the hardware on the machine. It appears there is a long but regular interval.

Here is how I would trouble shoot. Does the artifact occur only when you cut right to left or only front to back. Cut those srips one way and then the other. Determine the typical interval of the artifact. (It may not always be the same but does it typically occur at a regular interval.) If the grid is inches that you took the picture on it looks to be something like 1.25 to 1.5" Lets say it is 1.25". On a step and direction machine there are a lot of things that rotate... You are looking for something that snags, snarks, or horks, every time the head moves 1.25" IF it is a direct motion component, ie something like a pulley or wheel that rotates, without gearing then you can use pi*diamter=circumference to look for culprits. IE 1.25"/3.14159= .4" So go check wheels and the bearings of same that have a diameter of about .4"

I can't remember if those black roller wheels on the fast axis are about those diameter but if so, I would bet it is there. They are replaceable I think.

Otherwise clean everything!

Good luck.
 Subject : Reducing Laser Pulses on Universal Laser.. 03/15/2019 09:02:39 AM 
Ernest Ang
Posts: 22
Location
Hi all,

We have a 60 watt Universal Laser and need to laser cut something that has smoother edges and lesser laser pulse on the cut. We know it's impossible to eliminate all the pulses (duh....), but is wondering what can we do to not have the wider pulses as circled in red in the attached images.

We have been playing around with the PPI setting (from 100 to 1000) and cutting it multiple times with lower setting but to no availability. We would really appreciate any input you all have!

Thank you so much for your help!

 
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