I am engraving on slate and I have developed a problem. I created the file and run my material test to find the best setting for my 20w Diode Mr. Carve. The first 5 time I ran the engraving there were no issues with filling in all the areas, but on the 6 run I developed a problem filling in the corners. On the 6 run I was adjusting the power level on another layer.
I have looked through the forum and found similar issues and I have increased the intervals but that did not correct the problem. I tried filling with off set fill and fill. I have cleaned everything that I can clean. My laser does not have a focus adjustment, so I can not reset the focus. My setting are below. I am learning to use lightburn, but I have tried everything that I know to do.
Hi Thomas, as you’re using slate, have you checked the thickness, maybe you are losing the correct focal length,(out of focus).
the bottom picture looks slightly washed out compared to the top.
Hope it helps.
I’d suggest not using offset fill. I suspect what’s happening is that the variable power adjustment to accommodate for the speed change during the corners is reducing power to the point of underburning.
A few remedies if you insist on using offset fill:
Slow down. 4000 mm/min is likely much too fast for the design.
Enable Constant Power mode. This will essentially disable variable power. However, you may end up with the opposite problem of overburning at the corners
If you move to regular fill, make sure that overscanning is enabled.
A couple of other observations:
Your line interval seems like it could be too small. I suspect you’re losing detail. Have you run an actual interval test to confirm ideal line interval?
How is focus achieved on your machine? The burn seems relatively well-focused but curious based on your comment about it not being adjustable. You don’t want to leave anything on the table if possible.
Thank you for the suggestion. First I will say, the Mr. Carve M3 doesn’t come with any instructions and zero tech support. A friend of mine purchased the machine on Kickstarter. As far as I can tell the laser is pre-focused and I have a gauging block to set the laser 5mm above the surface.
Okay. So this is considered a fixed focus design. You achieve focus by changing the distance from the surface. I’d suggest creating some additional gauge blocks/sticks/etc. at varying distances from the 5mm reference. Then run horizontal and vertical lines at varying heights to confirm thinnest point. You may find that 5mm is not in fact the ideal height.
Thank you for the advise. I did turn on constant power mode and tried it in offset fill. That did better but did not completely fix the issue. I do think that most of the time regular fill looks better but it adds a lot of time to the project. I just had to scrap the messed up tile. On the next tile, I again tried offset fill, but the lines were to faint in spots (deferent spots) this time. I changed the stenting to regular fill and turning on constant power mode. I will just have to live with the extra 6 minutes per tile. Again, thank you that did fix the problem.
I also use my laser to engrave the stars on wooden flags that I carve. The laser will till engrave on the wood as much as 10mm away, but starts having issue any further away. I have to be careful not to have more than a 5mm variance when I cave the area in the union or I have to break the job up into smaller areas.
Deliberately defocusing is a legitimate technique if you’re going for a particular effect. However, for sharp engraving the allowable variance in focus distance is surprisingly small. Even a couple millimeters of focus variation can make a significant difference.
