Is there a way to set acceleration by shape?
I’m trying to calibrate my newly built custom laser machine and would love a quick test at the different accelerations to know what the limits are.
Hi, just draw/duplicate your shapes and set each one to a different layer from == to 29 each with different speed.
Other way you could do a Material Test by clicking Laser Tools > Material Test
Different speeds same power.
Edited: Corrected.
We do not support acceleration - I believe @parsec is talking about speed.
Acceleration is set, typically, in the controller. For example, in GRBL, $120, $121, and $122 firmware config options control acceleration for X, Y, and Z. But we do not have the ability to change that from within LightBurn cut settings.
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There are plenty of tune up methods around on the Internet on how to make your machine run faster.
Usually you want the fastest acceleration that can be applied and will not outrun the motors mechanical abilities.
You can draw a couple of boxes, in line mode, increase acceleration by 25% until it fails. This needs to be done with higher speeds… usually 
You need to do this at a location with an object so it has time/distance to reach full speed. It won’t tell you if it can’t do it, so you have to listen for the fields moving faster than the motor can move… rattles or make unusual sounds.
You’ll know when it’s too fast… generally this doesn’t harm the machine, just sounds terrible. If you run it into the side of the frame, that’s not covered by this statement.
You’re going around all the safeguards, so it you break it, you buy it… so to speak
Good luck
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Thanks everyone. It sounds like I’ll have to find a way to manually add the gcode M201 to adjust acceleration in the file if I want to do this. My first material test came out terrible due to loose belts. I tightened the belts and the results are better, but I’m still getting squiggles in the corners, I’m assuming due to too much acceleration. Current limits are 3000 mm/s^2. Maybe I just need a tighter tolerance on my 3d printed mount, or maybe I should just get a small linear rail to mount the laser head on.
I don’t know what this is going to buy you. Unless you’re looking for a failure?
I thought the idea was to find the fastest acceleration… do you know of something that comes up to determine that from this output?
Those where just my first material tests. Both at 10-100 mm/s and 10-100%laser.
Lightburn creator(s) were nice enough to insert layer labels in their gcode output, making it easy to find the start of my square acceleration test shapes. There I was easily able to determine the start/stop of each shape by the M03/M05 commands and insert the appropriate M201 X/Y values to set up my test.
Acceleration Test 20240723-2024.gcode.txt (56.7 KB)
Based on this test I set acceleration to 400 mm/s^2. Since the machine could only reach about 45mm/s at this acceleration (v=sqrt(2ad) where d=5mm/2 for start/stop) so I re-rean the material test with 400mm/s^2 acceleration and speeds 5-50mm/s.
I have no idea how you came up with this…
However 45mm/s is pretty slow…
My Chinese machine has an acceleration of 45,000mm/s^2 compared to your 400mm/s^2. Mine is faster (less mass), but even still the stock Y axes are around 3000mm/s^2.
Not sure I recognize this, such as what is D?
Might try this site for computing acceleration distances and time… graphic display of results.
I still don’t follow what you are doing with the materials test? The small size of the squares limits any real testing…
A “snooze” reply, also there is no point in doing the test with several columns 1 is enough.
Snooze reply?
Here was too late.
And sometimes too tired.
I’ve been 3d printing for years, but I’m new to the laser space. Since I’ve done a lot of mods on my 3d printer I wanted to try building a custom machine for my laser.
I’m trying to learn how to calibrate everything and dial this machine in. I did another round of really tightening the belts and shimmed the laser mount to try stiffening everything up. I found this helpful video on testing the machine limits.
3018 PRO - Tuning GRBL settings by James Dean Designs
Since it was stalling out at around 10,000 mm/s^2 I re-ran the acceleration test from 1,000 to 10,000 mm/s^2.
I think I’m going to set my acceleration to 2,000 mm/s^2. The goal here is to move/accelerate as fast as I can while maintaining dimensional accuracy. I also turned on a 5% overscan for the filled numbers on this test. I’ll keep dialing this in. It would be great to have a kind of calibration check list like what Michael has created in Teaching Tech.
https://teachingtechyt.github.io/calibration.html
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