Laser speed vs. power: not strictly interchangable

I suppose what I write here is not new, but I just played around a bit with laser speed an power to see how interchangable these variables are. A bit more specific: I have a vector path I burn into wood, and I started off at 140 mm/min @ 20% power. Result: Nice!. So I thought: 700 mm/min @ 100% power should deposit the same amount of energy into the wood, i.e. yielding the same result. I already had doubts, because at any sharp corner in the path the laser needs to deccelerate and accelerate, most likely rendering any linear relationship useless. Turns out I was right. Result not so nice, many deep burns. Just for the sake of learning I did a third one with 2000 mm/min @ 100% power. This clearly shows lightly burned lines on long passes, and deep burns at angles. So, while in theory I guess it would work, it would require a much better power control of the laser in relation to its actual movement speed at any given time. I guess this would be possible, but is not in the firmware.
Doesn’t bother me too much - vector laser is fast enough, the few minutes saved are not worth amy hassle…
Here’s the results btw - left: 140mm/min@20%, mid: 700mm/min@100%, right 20000mm/min@100%.

@brent113 actually created an update that would solve (at least)part of) the issue here with the acceleration & deceleration. (Not sure if it would be exactly the same) but still would be a good enhancement:

Does require you to use lightburn or other software than Luban that actually supports this feature. And material properties are likely to have some impact on this as well.

I mean, a simple regular expression is enough to change the file over. For awhile this is what I did:

def calculate(match):
    return '%s P%s' % (match.group(2), match.group(1))

# Replace M03 G1 pairs with an inline G1 command
#
# M03 P60 S153
# G1 X13.5
#    |
#    v
# G1 X13.5 P60
editor.rereplace('^M0[3,4].*P([0-9\.]+).*\r?\n(G1.*)$', calculate)

That runs inside notepad++ using the Python Script plugin.

2 Likes

Excellent! Will try this!

Hi @brent113 and @brvdboss,
I just modified my snowflake as brent113 suggested, but the result is not different from before. I assume I’m a bit obtuse here - is the feature already in the Snapmaker firmware, or is this a suggestion that Snapmaker still has to merge into their sourcecode?
Thanks for clarification!

Requires my firmware build, currently in private beta. It’s not compatible with the latest firmware just released. If you haven’t yet upgraded I can send you a link to it.

Unfortunately I cannot make it compatible with the latest firmware release because of all of the glitches introduced in 1.14, and unfortunately it’s not backwards compatible as they changed the comms protocol with all previous versions, and you cannot downgrade android apps.

Thanks for the offer, but as of now I’ll stick with the official version. I certainly at some point will go down that rabbithole and might get back to you.
Bummer that they changed everything - is this “mendable” in the sense that with a bit of effort your mod’s can get back to working?
Btw.: Did you perchance also increase the PWM frequency in your modded firmware? That would be tempting… :slight_smile:

No.

My mods still work, but I’m not going to test it as if I update to the latest touchscreen firmware I will be stuck with the buggy firmware as it cannot be downgraded like the controller can. Since the comms protocol changed the controller is no longer backwards compatible with the touchscreen and downgrading the controller may have new issues not previously seen.

I think the changes are small, but mainly I don’t want to risk it as my machine is currently fully functional.

Just have seen that they accepted the pull request and merged the feature - status: Testing… Looking forward to that!

I had a slightly more complicated laser engraving job and hit limits with Luban - tried Lightburn and can just add my recommendation for that program to the numerous recommendations of others! Very good program, did not even wait for the 30 free trial days to expire, directly bought a license.

1 Like