Problems with laser setup

Not a cutting topic, but more appropriate here than any other category.

$11, $110-$112, $120-$122 but these were too much, the axis were just jumping around. Lowered the settings back down. At least you gave me an idea with what I can play with next when I have a bit more time again

Seems like there is something wrong with your setup.

What program do you use to generate the G-code (which post processor do you use - if relevant)?

What program do you use to send the G-code to the X-carve?

Post your current $$ output here.

Thanks for starting a new thread. I will get to you with more information later tonight or tomorrow.

Here is my current settings:
$0=10 (step pulse, usec)
$1=255 (step idle delay, msec)
$2=0 (step port invert mask:00000000)
$3=4 (dir port invert mask:00000100)
$4=0 (step enable invert, bool)
$5=0 (limit pins invert, bool)
$6=0 (probe pin invert, bool)
$10=115 (status report mask:01110011)
$11=0.020 (junction deviation, mm)
$12=0.002 (arc tolerance, mm)
$13=0 (report inches, bool)
$20=0 (soft limits, bool)
$21=0 (hard limits, bool)
$22=1 (homing cycle, bool)
$23=3 (homing dir invert mask:00000011)
$24=25.000 (homing feed, mm/min)
$25=750.000 (homing seek, mm/min)
$26=250 (homing debounce, msec)
$27=1.000 (homing pull-off, mm)
$30=255. (rpm max)
$31=0. (rpm min)
$32=1 (laser mode, bool)
$100=39.960 (x, step/mm)
$101=40.000 (y, step/mm)
$102=188.976 (z, step/mm)
$110=8000.000 (x max rate, mm/min)
$111=8000.000 (y max rate, mm/min)
$112=500.000 (z max rate, mm/min)
$120=500.000 (x accel, mm/sec^2)
$121=500.000 (y accel, mm/sec^2)
$122=50.000 (z accel, mm/sec^2)
$130=790.000 (x max travel, mm)
$131=790.000 (y max travel, mm)
$132=100.000 (z max travel, mm)

For laser work try the following changes and see what you get.


If you can, post an image of the design.

Oh I already see my mistake. I never changed $0 to 30 when I changed the acc. settings

I will try those settings first thing in the morning.
Are those settings for laser work only? Or can they stay at those values?

If that test works ok, we might change some of the acceleration parameters.

Each tool operates best with its own parameters.

Since you are using my version of grbl you could invest in PicSender (at about $25). It works with my version of grbl to load in the correct parameter set by pressing a single button.

There is a free trial version you can download to see if it would work in your workflow.


Sorry, yesterday was a bust - the wife had the day all planned out already! :slight_smile:
I hope to get to this today.
So if I understand correctly, the values for these settings($0, $10, $11) are also some(in addition to $30, $31, $32) that should be changed back and forth as you go from carving to laser?

I tried to do a ton of reading/research in the forums here while getting everything running, in an attempt to not ask a bunch of annoying newbie questions! :smile:
Somehow though I missed seeing to change those values as well. :confused:

There are more that change from spindle to laser and back.

You can run with one set of parameters, however, you won’t get the best results. Depending on the type of laser work you will be doing you might not need to change them.

However, since you are seeing a problem I think you might see better results by changing the values.

I wanted you to change just a few at first to see which ones affect you most.

1 Like

Sorry this has taken so long! I certainly was not ignoring you. The last couple weeks were rough, wife went out of town for a week while we had sick kids, then she got back and was sick, so between those things and working I’ve had no time to spend in the shop until last night!
So here is my attempt at a quick and dirty image last night, just an outline. You can see in the pic that it seems kind of “spotty”? Almost like dashes and dots? This was done on sanded pine, so not sure how much the wood itself is playing a factor.
Just to go ahead and throw it out there, I have triple checked everything on my machine:
-all v-wheels are tightened correctly
-belts good
-pulleys good
-laser mount tight
-focus, I believe, is as good as I can get it(done this many times) and using blue loctite
-just wanted to note that my laser dot actually shows up as a very small, but distinct, rectangle. I know I’ve read the info that it is not a true dot but really an oval shape. I can say my definitely looks much more like a rectangle than an oval though - not sure if that is anything to worry about or not - of course maybe my eyes are just that bad!
-laser set at 3" from material surface to front face of the heat sink
-my current GRBL settings are exactly as earlier in the thread, except making your recommended changes for $0, $10, and $11
Still seems to kind of be “jittery” when running, may be why some of those lines look kind of shaky/zigzag ? Never seemed to notice this before when carving. Of course this is doing a much finer line - also could it be I am seeing the lines being a little jagged due to it being just an outline versus a fill?
The other pic is the settings I used in VCarve Desktop to generate the gcode.

I did find I had a pic with me at work that shows my laser “dot” - the best you can get a photo of it anyway…
The red rectangle is more like a reflection the laser is giving off from the lense - not from the flat black material.
The arrow is pointing to what is the actual “main dot” of the laser.
This was done at S10 setting and shows the laser diode is probably at about a 45 to 60 degree angle?

Use this set of grbl parameters. I’m not sure why it is “jittery”. May be the G-code.

Laser.txt (1009 Bytes)

Actually, that is the shape of the laser die, so you have really good focus. Some people defocus slightly to get an oval. You can buy an after market lens that will give you more of a spot if that’s what you want. If you are going to use the focus that you have, line up the angle of the “dot” at 45 degrees. This will give you the same size line for horizontal and vertical lines, and also give benefit when running raster images at 45 degrees.

Read through this entire thread on the JTech web site for setting up Vcarve. There is some useful information down below the post processors that may help with the “jitter”.