Dark Lines JTech 3.8W Laser Upgrade (LaserEtch)

Thank you,

We just purchase Pic Engraver Pro 5, and pic sender (order 856). We look forward to receiving the licence keys.


Okay, we are about to flash the JTech GRBL to the arduino using XLoader but dont know which “Device” we should select.

We have an arduino board for an xcarve.

Did you backup your original X-Carve grbl settings in the PicSender GRBL menu first?

Select the UNO in the device list.

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Yes we did, we are now using the PicEngravePro 5 program to create the gcode.

Is there a page on your website that has recommended settings for this software?


There is a Tutorial button on the main page. Use the Analog/PWM engraving profile. It has more features then GRBL PWM.


We have updated our Arduino to the JTech Firmware but are unable to switch back to the 0.9j firmware as described in this post: Where is the laser engraving category?

Once we flash the 0.9j firmware we are unable to connect to the arduino… Any thoughts on how we can resolve this?

First look in the Device Manger and see if the UNO is showing a com port #. If not, unplug the UNO’s USB cable, wait a few seconds and then plug it back in. Then try connecting again with PicSender & the com port # shown in the Device Manager for the UNO.

If it still will not connect, try a reboot of your PC.

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Please see this Screencast. It will show you the errors we are getting.


We are able to reinstall the JTech firmware but unable to connect to the machine when we install the 9j version.

Maybe the screencast will point out something I am doing wrong?

Are you using the grbl 9J hex at the top of the Master Branch list on this web page? https://github.com/inventables/grbl

I just tested it here and it connects fine.

Do a right click on this page and save as somewhere on your PC then remove the .txt extension and try it.



That was it!!! i was using a hex file that was incorrect!!!

Thank You So Much!!

Highly recommend the PicEngrave Products and support by the way!


We are trying to create a cutting board for a wedding gift for a close friend. We are using the JTech 3.8w laser.

We would like the end result to look something like this.

Note how the engraving does not look ‘burnt’.

What settings would you recommend using to achieve this look?

I can only give you a starting place for the settings. You will still have to go through a trial & error period to get them fine tuned.

Depending on the wood your engraving on, you should be in the 130-150 inch per minute feedrate range with the 3.8W laser. The image should have a min of 100DPI resolution which the PicEngrave image editor saves at after resizing/editing. With no shades like in your example, the Threshold dithering algorithm would work the best.

The Pixel Resolution (stepover) should be .007"-.008" and since a dithered image is 1bit B&W, use a min laser power value of 0 and max of 255. This is with the J-Tech PWM grbl. If you plan on using the X-Carve’s grbl 9j, the max is 12000.

Use the Skip White Bkgnd to cut down on engraving time. It will ignore the outer white areas when generating the gcode.

I would test these settings on a scrap piece of wood first.


I will use a small wire or or stiff bristle plastic brush to remove the char from the cut the harder the wood the better it works


when using a laser i used transfer paper to protect wood from burning mark.

I just got the 3.8 laser I need help with programming it. I use the laser edge software decrease the G code all the laser does is turn on does not move. PLEASE HELP!!!

If your referring to the J-Tech LaserMode grbl 9g, check to see if grbl setting is $14=1. If it’s set to $14=0 it will not move.

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Ok I’ll check that. It will move from start to work peace then stop and do nothing. I have it wired for PWM so it should turn on and off just moving x and y with z set to correct height. Can you help with the laser etch program? How do you set size of work peace? Thanks

Laser Etch is a J-Tech Photonics program. Jay can help you with that question.


Hi Michael,

On the image tab in the setup you have the “go to center and pause” checked with probably a very large number. You need to go to the “G Code Flavor” tab and click “GRBL”. This will change the numbers to seconds. Put in the appropriate amount of seconds you want to pause. I think you probably have it set to 5000, which will be a very long time to pause.

Here is a tutorial on using laser etch. It talks about how to format your input picture for the best performance as well as setting it up and running. It discusses setting the size for the final image as well based on your laser spot size and your input image resolution.

We recommend using the J Tech GRBL, but it will also work with the Inventables version on your machine. For J Tech GRBL the laser on is M3 S255 for full power. For the Inventables firmware it is M3 S12000. Instructions for setting up the J Tech Firmware are located on the X Carve instructions page under “Picture Engraving Instructions”.

Hope this helps!

Best Regards,

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first if all the more power the deeper it burns and also the dot size grow up.
you could try to use a air compressor and construct
a blower to the laser point when it burns
second go faster with higher power or try les power.
third try better lense to get a sharper focus