Laser - UCCNC - Lightburn

[MikeC]

I'll have a go with the gcode tomorrow and let you know how it turns out.

[MikeC]

I did some experiments, see attached. There is a minimum Q value (20) set so the laser won't fully turn off. Of course, it can be set. You can see the dark overhangs where the laser is powered low. Does it seem to be usable?

The attachment laser.png is no longer available

The files worked well. I ran one of the slate ones and a wood one and both came out well with no problems.

[mac6]

I just completed installing a diode laser on my DIY CNC machine. I have the laser working as it should - (varying strength from 0 to 255). I also am using Lightburn when I have the laser mounted to my 3D printer. For a device I am using grbl. It burns correctly straight from Lightburn to the printer. However I cannot get a gcode file to work on UCCNC. Obviously since UCCNC uses M10 Qxx for its laser out put I figured I would have to change somethings in the gcode file, but nothing I try seems to work.

My question is for those that are using Lightburn, how are you getting the correct gcode to run on UCCNC? I have tried all versions of grbl. What is the secret?
Special device created in Lightburn?
Separate post processor?

It sounds like you've made some great progress with your diode laser and Lightburn setup, but you're running into issues with UCCNC and getting your gcode files to work. One possible solution is to use a separate post processor for UCCNC. This can help to ensure that the gcode output from Lightburn is compatible with UCCNC.Read the some suggestions of 3d printer here.

To do this, you can select the "GCode" button in Lightburn and choose "Edit Post Processor". From there, you can select "Generic GCode" and then "Save As" to create a new post processor specifically for UCCNC. Once you have the new post processor created, you can select it in the Lightburn settings and then generate your gcode files as usual.

[heffer86]

Thanks. I'll try to find out shomething useful.

I have my Optlaser setup and working. I am not running into issues with files from Lightburn. I have attached the original and the LightburnLoader 1.3 output one. I downloaded the example files in this post and they burned fine. I am thinking there is something incorrect in my lightburn output (GRBL-M3)

Here is how is looks

[dezsoe]

Your g-code is good. I checked the sample files and they scan 1500..2750 mm/min, most of them 2000, but your code scans at 3000 mm/min. It may be too fast for your laser and/or the mechanics. Try to generate it at 2000 mm/min or below. Also, check the X movements: it may have a loose coupling or the laser head is moving a little bit.

[heffer86]

Your g-code is good. I checked the sample files and they scan 1500..2750 mm/min, most of them 2000, but your code scans at 3000 mm/min. It may be too fast for your laser and/or the mechanics. Try to generate it at 2000 mm/min or below. Also, check the X movements: it may have a loose coupling or the laser head is moving a little bit.

dezsoe Thanks for the information. I am still left with even more questions now. I hooked the laser up to my other (Machine 2) AXBB-E machine (port 17 for PWM and 5v0). It burned the file perfectly (Pic below). I though my problems were solved since on Machine 1 I had it hooked up via an Isolated output (O3). I hooked the laser back up to Machine 1 via O17 and it produced the same bad result. I am at a loss for ideas at this point. Same control boards same software same file configuration. Ideas? I even slowed down Machine 1 to 500mm and same result. The laser head is rick solid on the CNC machine also.

File that ran fine on Machine 2 and still have issues on Machine 1

nova_UCCNC.gc.txt

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Picture of the file burring perfectly on Machine 2.

Picture of the same file on Machine 1 (I didn't finish it since is was burning bad).

[iOne]

Hi Heffer86,

I am just passing by but I read your last post and I thought to try to help since this forum is very quiet and not many people actually reply when somebody is looking for help. For what I gather from a quick read, you have 2 machines giving you different results? Are these 2 machines identical? if not, you cannot use the SAME lightburn file in both machines. You must calibrate your settings in lightburn for EACH machine. What you describe in a photo above as "double cutting" is actually the offset of the laser going to the left and then to the right (scanning). The laser (or machine) is not fast enough to start at the same point when going in one direction and then when coming back. There is a setting in lightburn under "device settings" > "scanning offset adjust" to compensate for what your machine cannot achieve. In general, that adjustment is reduced if you make the speed and acceleration faster in your machine. For my CNC I have 2 settings, one for router activities and one for laser. The laser one have very fast speed and accelerations in order to reduce the calibration in lightburn that I mentioned and for more accurate laser engraves but makes the machine shake so I do not use the same speeds as a router. This is to say that you have to find a middle ground between making the machine fast enough to keep up with the laser or make lightburn delay the laser signal to wait for the machine to gather speed and find the same point to fire the laser when going to left and then right. Also you need to play with the 'overscanning" option. That is the distance that you define for the machine to go beyond the edge of the engraving, decelerate, stop, and accelerate in the oposite direction again so it can reach the engraving speed before the engraving point. In summary you need to google "Scanning Offset & Overscanning" if the 2 machines are not IDENTICAL. I hope this helps.

EDIT: You can check if what I am saying is true by using a magnifying glass on what you call "ghosting" or "double cutting". You will realise that the 2x "P" or 2x "T" are not exactly parallel to each other, one P is slightly below the other P. That's because one P is made when going to left and the other one when going to right.

[heffer86]

Hi Heffer86,

I am just passing by but I read your last post and I thought to try to help since this forum is very quiet and not many people actually reply when somebody is looking for help. For what I gather from a quick read, you have 2 machines giving you....

Thank you very much for the information. The machines are electronically identical just not mechanical. Different steppers and motors. Any yes I am getting that overscan affect you talked about. I am doing to dig deep into the settings in Lightburn. I just took my AXBB-E out of the machine that was having problems and put it in my other machine. Everything burned fine so yes it must be related to the GCode file.

Thanks!

[iOne]

Hi Heffer86,

Yes, different motors means not identical machines as the speeds and accelerations will be different. So you need different setting profiles for both machines. Just like you would normally test patters for different speed and laser powers to see what suit best the engraving or cutting on different materials, you also need to do the same for scan offsets and over-scanning for both machines. Normally engraving a "square" is a good idea so you can measure the shift between both directions of engraving. Also the scan offsets settings requires you to enter also the speeds that you are going to use engraving so lightburn can compensate (delay the laser) for different engraving speeds that you may use in the same machine. The "7" clearly shows at the top that the scan offset is wrong. So a good googling with the terms that I told you will put you in the right track. Good luck.

[heffer86]

Hi Heffer86,

Yes, different motors means not identical machines as the speeds and accelerations will be different. So you need different setting profiles for both machines. Just like you would normally test patters for different speed and laser powers to see what suit best the engraving or cutting on different materials, you also need to do the same for scan offsets and over-scanning for both machines. Normally engraving a "square" is a good idea so you can measure the shift between both directions of engraving. Also the scan offsets settings requires you to enter also the speeds that you are going to use engraving so lightburn can compensate (delay the laser) for different engraving speeds that you may use in the same machine. The "7" clearly shows at the top that the scan offset is wrong. So a good googling with the terms that I told you will put you in the right track. Good luck.

Thank you so much for the information on the Lighburn scanning offset adjust. I was able to get my burnings looking good. I was wondering if you could help me with the next issue that cropped up. While burning my next project I noticed that the laser isn't firing all the time when commanded. I though the laser/controller couldn't process the data quick enough. Then I ran it though the UCCNC laser plugin and it was able to pulse very quickly and produce the image. I prefer to use Lightburn since the image is a vector vs a PNG image. All the ones that are missed are very fast pulses for small burn areas.

Here is the part that isn't burning. There should be vertical lines where the red is.

Here is what it looks like using the UCCNC laser plugin

Here is the GCode, SVG and PNG image I used for the burn.

GCode_SVG_image.zip

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