Inventables Community Forum

Laser Output Always On

As I do not believe in magic, has anyone else experienced the JTech 2.8W continuous 10Vdc output with no control input? I have the control input completely disconnected.

Is your switch set on TTL or CW.

Set to CW, I changed nothing from the last project a couple of weeks ago. Hence me scratching my head, several hours searching/reading forum, and firing the distress flare to this knowledge and helpful group.

Explain a bit about your set up. Are you using The XController and Picsender or UGS. If so your switch should be on TTL. CW is continuously on.

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CW is constant wattage.
this setting is on full power all time.
how you would get this to work last time is the mystery.

change to TTL or transistor to transistor logic which allow it to switch on and off according to the input signal.

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@KennethConnell switched to TTL and not 10Vdc on output.

Running test project to verify in order to trust.


thanks @PhilJohnson was jsut typing that.

You also need to look at your GRBL settings on $30=??? and $32=?

$30=255 is the most common for jtech laser. this sets the RPM speed which will be setting for laser full on.

$32=1 this will turn on laser mode.

$31=0 this sets the RPM min speed which will set it to full off.

then you can set your laser in your program to max power=255 min power=0
also you can issue the command from console M3 S255 to turn laser on full and then M3 S0 to turn laser off

then you can also send command M3 s003 to turn laser on real low to see if there is a difference with that (it should be noticeable). and again with the off command. let us know.

@PhilJohnson connected to old splindle control wires (Red and Black).

Voltage is changing.

@KennethConnell will verify setting once test run complete.

So far so go

It might: but I do remember reading somewhere with the Jtech laser that it was described it as constant wattage. so I have always went with that when describing that setting on their board.

@KennethConnell @PhilJohnson

$$ in USGS reveals no $30 series

what version of GRBL is listed at the top?

Universal Gcode Sender version 1.0.9

$0=10 (step pulse, usec)
$1=255 (step idle delay, msec)
$2=0 (step port invert mask:00000000)
$3=3 (dir port invert mask:00000011)
$4=0 (step enable invert, bool)
$5=0 (limit pins invert, bool)
$6=0 (probe pin invert, bool)
$10=3 (status report mask:00000011)
$11=0.020 (junction deviation, mm)
$12=0.002 (arc tolerance, mm)
$13=1 (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)
$100=40.000 (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)

when you first connect (before sending the $$ command) it should list the GRBL version.
It should look something like this Grbl 0.9i [’$’ for help]

Grbl 0.9j [’$’ for help]

$$ (view Grbl settings)
$# (view # parameters)
$G (view parser state)
$I (view build info)
$N (view startup blocks)
$x=value (save Grbl setting)
$Nx=line (save startup block)
$C (check gcode mode)
$X (kill alarm lock)
$H (run homing cycle)
~ (cycle start)
! (feed hold)
? (current status)
ctrl-x (reset Grbl)

I believe that this version has known issues with laser.

read this post and possible consideration of updating GRBL for laser use.

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Thanks, I will give it a read.

The test run was successful, so I will get this project completed and dive into @LarryM knowledge (that I can undestand).

Thanks @CurtisCummings, @KennethConnell, @PhilJohnson and @AngusMcleod .

It’s guys like you that make this forum rock in spite of some whimpering.

Back to wood chips and charring.

Again Thanks

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UGH! (For laser use Larry’s 1.0) :smirk:


Glad it all worked out. It’s threads like this that help everyone on the forum. I responded with the intention of helping and instead ( when the brain trust got here) learned something. I had no idea that @KennethConnell was so knowledgeable about the Laser. He just went in my “Laser Bank”. ( notice what I did there lol”).

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Yea, Not sure what is cooler

Awesome forum group and knowledge expansion


Watching the machine operate.