Recently purchased Jtech’s 34W diode laser. I’ve done a couple of “Material Tests” from Lightburn and also done a test engrave and a test cut using Vcarve and its laser module. My first true project that I need to deliver is 16 golf ball markers made from 1/8” walnut with an engraving on it.
In my test engrave of the logo they want, I did 4 ball markers with 4 different laser settings to see what looked better. All 4 test ball markers/engraves were done in the 17w setting of the laser. The 4 engraves were:
400in/m @ 30% power
325in/m @ 30% power
250in/m @ 30% power
175in/m @ 30% power
As sort of expected, the 175in/m @ 30% power looked the best. It was the darkest of them all and yet, was still pretty clean and wasn’t too much of a “cut”. I’m going to play around with some more speeds and powers, but it got me thinking about this basic question…. for engraving on dark hardwoods like a walnut, which would be best….higher power (say 60%) at higher speeds or lower power (like my 30% test) at slower speeds? Or is it just truly a pure inverse? Meaning….would 400in/m @ 60% power look pretty much the same as 175in/m @ 30% power? Thoughts?
As you mention if you increase the power and speed you’ll end up with a similar result, slower or more power will go deeper.
One thing to watch is the faster you go the more the over scan distance will be which can dramatically increase the total time to run the part. I have kept my settings for my 44W on my OF Elite Woodworker to <25 in/min. for this reason. I’ve found Lightburn to be fairly accurate to see the impact of the speed if you’ve set up the Simulation Settings for your machine to match the configuration.
The one thing to watch is that the higher the power the more you’ll get more smoke/resin around the engraving (this is also impacted by your air assist pressure/flow), for some woods this is almost impossible to avoid but can be minimized.
Ultimately the key is to find the balance between power and speed that gives you the desired result without compromising the economics or resulting in a bunch of post processing.
Thank you for your input, very much appreciated. When you mention you keep your speed to <25in/min, is that for cutting or engraving? That seems awful slow for engraving. When I did my one cut test, I was running at 100% power in full 34W mode @ 30in/min and it cut through .25” walnut hardwood in 2 passes. I can’t imagine doing engraving at speeds of less than 25in/min. Or am I missing something or not understanding (VERY possible)?
I must of mixed up my conversion from mm/s, looks like most of my engraving settings (fill mode in Lightburn) are ~83in/min. with a few up to 200in/min., I typically run <30% power. The overscan dramatically increases the total run time to the point where the only way to make it work economically was to run it slower and at a lower power.
This is primarily based on making these: Cumberland Mountain Bike Trail Maps – Beaufort Range Designs As an example, changing the just the text in this map from ~83in/min. to ~130 in/min. adds a bit over 10 min to the run time on the 16x32 size. The amount this impacts your times will vary depending on the number and size of the design you are engraving. With these maps having a bunch of small sections of lettering the impact is amplified.
For line mode (again engraving) I can get above 230 in/min. since there there is no overscan without gaining run time. This is limited for me due to how the lines start (a bit of a stutter), something that I suspect relates to the code from Lightburn and how the Masso processes it but haven’t found a solution yet.
I haven’t done much cutting with the 44W, I mostly use my CO2 for cutting.
Gotcha, that makes sense now. Admittedly, I haven’t given much thought/testing to overscan yet. I’m doing overscan on my fills (2.5%), but haven’t started to consider or test variances there and with speeds. But after reading what you’ve shared, I can certainly understand how impactful it can be with the higher speeds/higher power. Thank you for sharing that insight. That is very helpful.
A couple of follow-up question for you, if you don’t mind. Those contour lines in your maps, are they all done as fill? Or are they small/thin enough to be done in line mode? What about the trail lines, I assume they are fill because of their thickness? And by the way, those maps are VERY cool and VERY nice!!!
Lastly, not sure if you’ve played around with Vcarve Pro and its Laser module, but I found it very interesting the difference between gcode outputs between it and Lightburn when doing the exact same designs. I don’t know that I’ve determined one is better than the other (yet), but it’s just interesting how each software approaches gcode-ing. I will say this…from what I’ve seen so far, Lightburn’s gcode output seems a little more cleaner/efficient, just from a pure coding perspective. I don’t know if or how it makes any difference from an actual production execution perspective though. Need to do some more testing.
Thank you again for sharing your insights and conversing with me on this. VERY much appreciated.
I have all my overscan set at 7% for the OF/JTech, based on the Masso recommended setting here: Setting up Lightburn
The trails and topo contours are all done as lines, we defocus (raise the Z offset in lightburn) the laser for the trails and the darker topo lines to make them wider. An interesting aspect of the diode lasers is the beam when defocused is slightly asymmetrical due to the layout of the diodes so you almost get a calligraphy pen stroke type line when you get defocused enough. You do have to increase the power the further you are from the focus point to make the same marking. I think you can also defocus the laser to fill large areas faster effectively compensating for a lower lpi.
I haven’t used VCarve for the laser at all, I tried it for cnc work but couldn’t get my head to work that way so I’ve stuck with Fusion and Lightburn.
Happy to help, it’s taken me over 2 years and too many test pieces to count to get to this point.
Thank you for the Masso link, I will definitely be looking through that.
Oh wow, VERY interesting how you do the contour and trail lines. Never in my wildest thoughts would I have ever thought of defocusing the laser to control how thick the lines were! VERY COOL!
I can’t thank you enough for sharing all of your insights. I have a lot to go play with and learn from now. Thank you, thank you, thank you!!!