Hi, I have a question about something that is going on with my machine and I’m betting the answer is stupidly simple but it seems to be eluding me at the moment.
I am using this calibration image to dial in my settings but the machine is acting weird lol. I have checked the GCODE and my GRBL settings and I can’t seem to figure out why it is skipping so much on the numbers above the gradient bars.
So first some settings,
Max speed is 3000 in GRBL and max acceleration is 1500 for both X & Y. Black and white speed are both set to 50 and double checking the GCODE shows all lines contain a feed rate of 3000 and power is 0 - 100.
When it engraves the top line and the gradients it moves at a constant speed but when it is engraving the numbers above the gradient, it seems to slow down and then speed up when going to the next number. It gives the effect of skipping blank lines. The feed rates don’t change and they are the same as the max for the machine so what could be causing it to slow down at the numbers? I was expecting it to maintain a constant speed across the entire image but that is not what is happening.
I thought maybe the planner was waiting on more data to arrive and causing it to pause but then why doesn’t it do that for the gradients too. I have tested it with other images and It seems to coincide with a large S value changes and not at all with gradual S value changes.
From the sounds of what you’re describing, I have seen the same on LaserWeb running on Smoothie. From what I’ve had explained it is the way that LaserWeb handles acceleration. Although, maybe +Peter van der Walt can give you a more definitive answer.
Travel moves (laser off) are likely set to a faster speed than “print” moves (laser on). If your laser firmware is anything like 3D printer firmware, that is normal. But, my experience so far is mostly with 3D printer firmware, and I’m still a laser n00b so take that with a grain of salt.
I thought that was the issue at first which is why I set the max travel speed to match the print speed. So all of the G0 commands should travel at the same speed as the G1 commands.
Next time you open up this image in laserweb… zoom in “alot” you will notice a slight dither to the image that coupled with what I am assuming is you running this from the User interface USB could be causing you some of this issue… try exporting the gcode and running from the sd card see if it improves… also check what your “Travel” speed is in the laserweb settings tab you may find you put in a different number
@Alex_Krause Thanks. Right now I wish I did have smoothie lol. Unfortunately I have GRBL on a Nano and it seems I’m asking too much of it lol.
Travel speed is set to 50 and I did double check the GCODE file, all feed rates are at F3000 which is what the machines max speed is set to for X & Y. So, in theory, the G0 commands should have travelled at the same speed,
I have tried compiling GRBL with different buffer sizes to no avail but I haven’t tried increasing the baud rate yet.
However, I think I may have confirmed that it is due to the speed at which I am trying to engrave. I slowed it down this morning to 1000 and it seems to be doing much better. Unfortunately this means that I have to dial down the speed and the power and the work is going to take much longer to complete lol.
How I came up with the 3000 feed rate was because the black was at the level I was wanting for an image I’m trying to do and I figured if 3000 got me the black I wanted then I could cut the engraving time down by running it at the max speed for 100% power.
Thanks for all the suggestions and help. It would seem it my expectations are a bit high lol.
