Hii,
I bought JTech laser 4.2W, and i want to connect it to my MPCNC.
I have the Rambo 1.4 board from Ryan, where should i connect the two wires from the JTech board to the Rambo board?
Do i have to change something in the software before i try to run the laser?
Thank you,
So connect your JTech to Fan1 on the RAMBo board. then make the following change to the v2 Firmware from Ryan:
in the Marlin.cpp file find the following block of code.
// Limit check_axes_activity frequency to 10Hz
static millis_t next_check_axes_ms = 0;
if (ELAPSED(ms, next_check_axes_ms)) {
planner.check_axes_activity();
next_check_axes_ms = ms + 100UL;
}
To fix the problem it needs to be changed to this.
// Limit check_axes_activity frequency to 10Hz
//static millis_t next_check_axes_ms = 0;
//if (ELAPSED(ms, next_check_axes_ms)) {
planner.check_axes_activity(); //< THIS IS THE ONLY LINE OF CODE YOU LEAVE UNCOMMENTED
// next_check_axes_ms = ms + 100UL;
//}
Once this is done, recompile , upload and viola laser works as it should. If you are using LightBurn make sure you change the units to mm/min under settings. under device settings change the Following:
S-value max --> 255
Baud Rate -> 250,000
Tool index -> 1
Enable laser fire button -> On
and your ready to test. Let me know if you want a material library, I have one from an emblaser 2 that should be pretty close to your laser.
Hii,
Thank you for your advise, I’ll try to do it during the weekend.
What i did for now is connect it to the Fan0 and use M106/M107 to control it.
I do see that the start and end of the lines isn’t 100% clean.
Done, and it’s working great 
I’m trying lightburn too, cut this from Balsa Wood 5mm:
The grid is 5mmx5mm.
I’m trying to cut plywood with my laser, it’s for airplanes.
I’m trying to cut a 2mm plywood, a simple circle of 3cm radius at speed 500mm/m and 100% power. i run it 50 passes, but it wasn’t able to cut it fully and all the edge is burned out.
Any advise if it’s possible to cut plywood with this JTech laser? different settings?
Let me know if you want a material library, I have one from an emblaser 2 that should be pretty close to your laser
Jeff, I would like to get your material library if it’s possible 
Do you have air air assist? That can really help. I have also read that the glue in plywood is especially tough.
Only the simple fan that came with the laser. will try it
Sorry Kamil, been traveling for the day job. I see you have a JTech 4.2 watt? which lens are you using? you should be able to cut plywood but 3cm is pretty thick. remember you laser will only hold an effective beam spot focus for a maximum of 3mm vertically. what you should do is raise your laser, at least 32 mm above you material surface and refocus your laser at that height. then you will need to to make a pass then lower your laser 1mm and run another pass. until you have cut though the material. with material over about 6mm you will struggle to keep kerf burn down with out air assist. I am currently experimenting with several nozzle designs for the JTech lasers, I’ll publish on thingyverse as soon as I have perfected the design. 500 mm/m is still pretty fast, slow it down to 100 mm/m and try with some 3mm plywood first. you should be able to cut that in 3-5 passes assuming you have correctly focused your laser. Also remember the harder the wood the plywood is made from the more difficult it will be to cut it. Also the type of glue or resin the plywood is laminated with will also play a role in how well you can cut it. If you need a part 30mm thick you may be better off cutting 10 of them from 3mm ply and glue them up. you can eliminate glue up issues by cutting location holes in the part and use a tooth pick or similar to line everything up when you glue it up.
Hii jeff,
Thank you for your replay.
I’m using the original attached lens, didn’t change it.
I’m trying to cut a 2mm plywood, the cut is a cycle of 3cm radius.
The plywood i was trying to cut seems to be very tough, it just burns and doesn’t cut.
I have 6mm plywood, which is much softer, and i was able to cut it. But i wasn’t able to find the settings in lightburn which would cause the z to lower every pass.
so you have to go into the device settings and enable Z axis. One word of caution when you do this, do not home the machine with the home button on lightburn unless you have a z Axis limit switch, otherwise it will crash your laser into the material or bed of your machine. Once you enable the Z Axis you can set the z movement per layer.
Hi Jeff, Is there a larger laser that can be fitted to the MPCNC. I’m using mine for carving but, I have a customer that really wants the laser cut pieces instead. The parts are for an Old West town he’s building for his train set. Plywood would be ideal. Thanks
The higher power diode lasers sometimes are just larger dots, so the power per area is not any larger.
I know very little about lasers, but my understanding is that to really cut through plywood, you need a CO2 laser. Last time I suggested someone experiment with that, I was scolded for encouraging dangerous machines.
Well then, here’s a diff question. Do they make 1/16" router bits to fit the 1/8" collet on the router? Those would easily cut thin birch plywood without the burning. If so, I’m not sure what the settings would be. How would I figure that out?
There are bits like that. They will wear out relatively quickly, and you’d want to baby them and do lots of tests to get good settings. I don’t know how deep they can cut either.
I have a 18 x 30 mpcnc and use a 1mm endmill at 300 to 500 mm/m at 2 mm DOC in cherry but start on the slow side and work up and may be able to go deeper but haven’t tried
Do those JTech lasers specifically allow 12V to the PWM pins?
I am in the process of building my CNC with a Odicforce laser, and the specs tell me that any PWM signal > 5V can kill the driverboard. It should be between 3.3V and 5V. A have read those specs on many other laser-modules too.
Perfect. Thanks Jeff.
Hey Tim,
Slow and easy is the best way. I’ll try these numbers and see what happens. I’ll use the Foamular first. Thanks.
Any time for a test yet?
Hi Tim, I’ll be working on it over the weekend. I teach 8th grade US History and I am swamped with work. Hopefully I can sit down, get my drawing made and start cutting. The virus thing has been really challenging for teachers like myself.