Hello all
hoping I can get some help here, Im on an Altmill and when attempting to use lightburn to generate code for anything I run into one or more issues.
If I place and object down (square or circle) to burn or cut lets say X 24 and Y 24
The laser will jog to about 32 Y and 23 X then begin to cut.
If I drop and object around X24 and 46 Y I hit like a stop at 24 Y and the gantry will go no further.
No codes or fault for this.
I can home the machine with no issues to 0,0,0
If I then if the object is larger but still within the boundaries of my machine size I receive a warning that my cut will be out of bounds.
I’m using and have tried both the lightburn experimental grbl and the default gerbal with no resolve.
I have my bed size set 48,48
@Stratmaster I’ll try to help, Mike, but, no offence meant, your post is a bit garbled and I can’t figure out what your problem is.
In your second sentance, are you saying that the dimensions of the object that you want to laser burn is 24 x 24?
No offence taken
Very sorry for the confusion
I believe now I just have a complete misunderstanding of light burn operation.
1st issue was the placing an object (square tool) in light burn around the coordinates 10 X and 40 Y would start the operation just slightly off home. This was opposite of my desired position.
I believe I have resolved this by selecting the lower left Job reference.
2nd If I draw an object around 20in square I receive an error that it is out of the area (cant remember the exact phrase)
Im pretty sure this is my lack of understanding how LB origins work.
3rd is how to set the correct Z height to the material
I do believe this is done in the layer settings
I guess Im spoiled with Gsender and other just simply hitting the Zero button rather than depending on my math to not crash my Laser into the material.
Hope this clarifies
Thanks again
Related to 2 - if you are placing/drawing right on the edge of your bedsize, the overscan component of lightburn is what causes the out of bounds warning.
Related to 3 - you can save the gcode to use in gsender, this is what I do. I then set my laser with the template sienci provided, zero the z, and start the job.
@Stratmaster With the laser, you set Z0 so that the laser is perfectly focussed on the material surface. I don’t know what laser you have, but they are all the same in this respect. In LB, you would simply start the project. In gSender, you would ensure that you have set Z0 at that focus height, then run the project.
Hey thanks much, that a huge help.
Thanks again.
Thanks I never would have thought of this.
So much to learn and me being a slow learner is not so useful.
thanks for taking the time to answer.
is there any grbl setting I should change for laser setup
I’ve tried to burn and image, with the layer set to 20% @ 80ipm in greyscale mode
and the image comes out charred or burnt.
I reduced power and changed the speed and to the best of my ability i can not see a difference in either.
Image still looks cooked.
I’m using an Opt Laser 70watt
Any help is much appreciated
@Stratmaster If you are using a 70watt laser to do pics, you are in serious overkill mode. 
I’m wondering if that is a typo. I can’t see anything that powerful on the opt laser site.
Are you designing in LB and sending gcode to gSender, or doing everything in LB?
Have you set sMax and $30 to the same value?
If no typo, you are looking at 14W tracking at around 2000mm/min.
I have a 7 W laser and only run it at 80% max, if I am desperate.
I don’t know what material you are destroying, but i feel you will char prety much any wood with the power and speed you are going with, if its indeed a 70W unit.
To get down to what I am used to, you need to double your speed annnnd half your power and maybe, just maybe, you might discover uncharred spots indicating you are homing in on workable settings.
70W.. My word, my garage would leak so much light, the neighbours would think I finaly succeeded opening a portal to that evil dimension they suspect me trying to come in contact with.
Tell me more about that laser unit..
My apologies gwilki, 45 wat Opt XT8-45. I swear not only do I make it difficult on me I do the same for those trying to help
I’m not sure where to locate sMax
$30 should equal ???
Thanks again
@Stratmaster No apologies needed, Mike. I just figured that it was one hell of a laser.
As to S value max (not sMax as I wrote) and $30, I set them to 1000. You will read recs to use 255. Either one will work. On the AltMill, 255 makes no sense to me at all since that value was chosen because of increment limitations of the 8-bit Uno. FWIW, I didn’t use it then, either.
In LB, S Value max is found in the device settings menu. That value must be the same as #30 or weird stuff happens.
In terms of feeds and power, you just have to play. The LAHobby guy has free files that burn a grid, the rows are power and the columns are speed. (I may have that backwards, but you get the idea) You run that file on the material that you are using and then you can choose the colour that you like from the grid.
Yea I’ve been watching a lot of LHG on the YouTube. Ill look for the files your referring to.
I have the same setup as Dana @ Buckys Custom. I could reach out to him as well. I just hate being a pain.
Ill look for LHG’2 files give that a try and report back.
I’ve had the laser well over a month used it to cut with but then that work thing and life got busy.
Another issue that’s driving me crazy is that my Y axis is inverted in LB.
My current settings are.
Are you saying technically there’s no difference between 1000 & 255 or should I change the both to 1000
Spindle is set to 0 currently, I surfaced a board late yesterday
GSENDER
$30=255.000 (Maximum spindle speed, rpm)
$31=0.000 (Spindle Mode, )
$32=1 (Laser-mode enabled as spindle, Boolean)
LIGHTBURN
$30=255.000
$31=0.000
$32=1
Thank You again.
@Stratmaster As long as S-value max and $30 are the same value, it will work fine. I prefer 1000 only because it makes it easier for me to read the gcode later. If 1000 is top power, then 35% power is 350 in the gcode. On the other hand, if 255 is full power, I need a calculator to see what 35% is.
As I understand it, the whole argument for 255 was based on using an 8-bit controller in the long board. An 8 bit controller can only handle 255 increments. Using 1000 didn’t change that. It didn’t result in adverse results, either. With the SLB and the SLB-EXT, that limitation is gone. They both use a 32-bit processor.
LB has always recommended using 1000. Sienci recommended 255, and it still does as far as I know. It’s your call.
re: inverted Y moves. This is from the LB help
In Lightburn on the Console tab enter $$ in the command field. Look for $3 in the list. If it is set to zero, enter $3=2 and press the enter key on your keyboard to change the direction of the y axis.
If this works in LB, it may mess things up in gSender, so watch for that.
Ok, I found the test stuff from LHG
I changed $3=6 to $3=2
This inverted my X axis.
No big deal
I decided to just save the .gcode and run it in gsender. I have no probe with that.
At least I wont forget to change settings and kill something.
Playing with speed and power
currently 140ipm @20% with reasonable results burning text (im sure I can further refine this with exp)
I do have an issue where the txt are printed in reverse
In LB I have the machine origin set to top left which is the Alts home.
One more thing, after the it has completed the the machine parks in to the left of the bun task then promptly crashes in to hard stop.
I have set the parking spot up and slight right then save the gcode hoping this would help but no joy.
Thanks again. With your help im so much less frustrated and actually making some progress