Raised Sections on Edges of Engravings

I am dialing in my laser and when I did a power table engraving I noticed that there are these raised edges on the sides of the boxes. All of the boxes were drawn in Lightburn and the power and speeds set (the bottom row of the picture shows 90% at 200mm/s). I’m not sure if this is a hardware issue or some setting in Lightburn.

Your scans aren’t aligned. If this is only at 90mm/sec, you have significant backlash on your machine (unless these are only 1mm in size, which I doubt).

What you’re seeing here is all the scans running from left-to-right on one side not meshing properly with the ones going from right-to-left. Each alternate line is offset from the one before. If you were running 500mm/sec or more, I’d suggest tuning using the Scanning Offset Adjust table in the Device Settings. Since this was relatively slow, and these offsets look large, I would look for mechanical play or slop in the system. Loose belts, carriages, bearings, pinion gears, etc. If you make sure everything else is buttoned up first, you should be able to reduce this a fair bit, then dial in the last bit with Scanning Offsets.

I double checked everything to make sure that it was tight and then ran another test. The below picture shows a rectangle which was done at a speed of 100 mm/s at 10% power and the ridges (circled in red) are still present.

I can’t find any other hardware issues that are present so I am fairly certain that this is a settings issue. The 10% power engraving test looks identical to the 100% power engraving test that I did the other day.

As for the speed, running at 500 mm/s as you suggested, I cannot run at any speed above about 300 mm/s as I receive an error message on the controller “no enough extend space.” I have tried resetting the origin to a more centralized location on the bed but any speed above 300 keeps giving me that same error message.

What is the engraving acceleration set to on your machine? (Edit > Machine Settings)

To get rid of these areas, you’ll need to set up a scanning offset table. Read here:
https://lightburnsoftware.github.io/NewDocs/ScanningOffsetAdjustment.html

The scanning offset table fixed those side ridges!!!

Settings

Above are the engraving acceleration settings. Do these settings effect the outcome of a power table? I set one up and ran it and all of the squares came out the same darkness even when I set the power as low as 1%. They all look like the laser is firing at full power. Thank you for all your help with this stuff.

1500 mm/sec^2 is pretty slow for engraving acceleration. How large is the machine?

The cutting bed is 620mm in the X direction and 420mm in the Y direction. I set all of the settings based on the build guide that I got online.

I don’t know what “custom machine” means, and what combination of stepper motors, drivers, and hardware you’ve got, but for a Ruida based machine of those dimensions I would probably start with 3000 mm/s^2 acceleration in both directions to start with and if there’s no problems with losing steps I’d work up from there. X can probably go higher than Y. Depending…

500 & 1500 mm/s^2 that you are showing is REALLY low acceleration and it takes a mile to get up to speed which is likely why you have the “extend space” error.

Thanks for the info Hank. What I mean by custom is that I built the machine using plans that I found on a youtube channel (Further Fabrication) so I am not using a pre-built laser.

I changed the acceleration settings for both X and Y to 3000 mm/s^2 and didn’t notice any change in my engraving. I tried to run at a higher speed (200 mm/s) and I still received the extend space error. I manually changed the X acceleration in the controller to 5000 mm/2^2 with no change. When I read the controller in Lightburn it still says that the X value is 3000 but the controller says 5000.

Settings

I then ran the below tests with the speed and power settings for the top one being 150 mm/s Min power 10% and Max power at 30%. The bottom settings were at 150 mm/s Min power 0% and Max power at 1%.

When looking at the ammeter the top one would go up to about 18mA and the bottom one would go to about 9mA. Using a pair of calipers shows the 30% power engraving to be 0.88mm deep and the 1% power engraving to be 0.4mm. These power settings don’t really make sense to me.

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