JTechPhotonic mount for x-carve

where can i buy the laser from ?

Right here @JeromeGJohnson

Yet another JTech 2.8w mount for the X-Carve. Needed to vent the smoke / cool the laser but I didn’t want to use a vac. Still a work in progress but it should work fine with a stronger fan. This mount slides into the DeWalt spindle carriage. Might work on a smaller mount for the DC spindle carriage once I move the laser to the smaller machine.

EDIT: Just got a crazy strong fan. ~130cfm noisy, fast and truly amazing. Delta PFC0812DE

Pics of the latest prototype with the fan installed. Have not mounted it on the machine yet. Will hopefully get to it this weekend.
Also thinking about building a mount for the electronics. For now I wont worry about it.


Nice rig for the fan and laser!

@IanWatkins Super cool power meter Ian! Have you published the build for this? Would love the recipe to build one and maybe add a fan speed display / control to it.

@JeremyHill Thanks!

Here is my quick and dirty way to heat sink the Jtech 2.8 watt laser head.

I used an old cpu heat sink. (yes it is a bit large but it was what I had on hand.) Put a little heat sink grease between the laser heat sink and the cpu heat sink. I used self tapping screws. Works like a charm keeping the laser cool.

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Finally got to test fit the fixture on the X-Carve. So far I’m happy with the results. Im printing the official JTech laser driver mounts to see how it will work with the hose. Not sure yet how the hose will work. Might have to suspend it above or tie it down to the cable chain mid-way.

I’m curious to see if sucking the smoke by the laser’s lens will contaminate it with soot.

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Im sure it will over time… but this fan really sucks so the smoke doesn’t linger around much. Using the Laser Etch software in demo mode. Assuming that’s why only part of the image is generated in GCode.

Ill upload a video soon.

My Lifeproof phone case seems to haze the video a bit… but you can get the idea of the fan noise and smoke evacuation. Video Link

@DavidSell There is information in the Jtech manual on how to hook into the two voltage outputs on the laser driver to give the necessary info plus some example Arduino code to convert to Amps/Watts output. Page 18 of this PDF shows you how: http://jtechphotonics.com/wp-content/uploads/2013/05/Instruction-Manual-HCDBSAFDA-J-Tech-Photonics-Inc-V1_2.pdf

I used a Pro Trinket and a LCD display for mine but you could use anything really. I didn’t publish a build as such, too busy building it :smile: but my Sketch is below if that helps, LCD (output) takes six pins and the analog reads are are on two pins (input). I even power the monitor from the laser driver by taking 12v from one of the safety interlock loops. So if the monitor is off, I know the driver isn’t armed even if powered. Sketch is for “standard” power on the 2.8W driver (three jumpers):

#include <LiquidCrystal.h>
LiquidCrystal lcd(12,11,6,5,4,3);

float voltsTP1 = 0;
float voltsTP2 = 0;
float current = 0;
float watts = 0;

void setup()
  lcd.begin(16, 2);

void loop()
  current = GetAvgCurrent();
  watts = current * 1.22;

  if (voltsTP1 < 0.2) {

  } else {


float GetAvgCurrent() {

  float CurrentValue = 0;
  float CurrentValueAvg = 0;
  int i = 0;
  while ( i < 250 ) {
    voltsTP1 = analogRead(A0);
    voltsTP2 = analogRead(A1);

    voltsTP1 = voltsTP1 * (5.0 / 1023.0);
    voltsTP2 = voltsTP2 * (5.0 / 1023.0);
    // Calculate current for jumper setting 1.5amps
    CurrentValue = ((voltsTP1 - voltsTP2) * 3.61) / 1.83;
    // For normal reading over 0 set it in the average
    if (CurrentValue > 0) {
      CurrentValueAvg = (CurrentValueAvg + CurrentValue) / 2;
    // Catch the glitches that say are negative and make them zero
    else {
      CurrentValue = 0;
      CurrentValueAvg = (CurrentValueAvg + CurrentValue) / 2;

  return (CurrentValueAvg);

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SWEET!! Thanks for sharing this @IanWatkins! I will definitely get one of these going.
Had a good 3 hour burn last night to do a logo on MDF. I know the machine can do this in 1/2 the time if I tune the laser power and feed rate.

@IanWatkins, I really like the LCD readout idea. I have a couple of stupid questions, if you don’t mind…

JTech says

the connections to these test points are voltage divided to be able to work with 3.3V micro-controllers

and in their example they use V*3.3/1023 to get the readout from TP1 and TP2. Did you change something on the driver to use a 5V Pro Trinket? Why did you pick this over a 3.3V one?

What is this 1.22V ?

EDIT: Also, the averaging function from JTech example that you also used looks strange:
50% * value_250 + 25% * value_249 + 12.5% * value_248 + 6.25% * value_247… ??

Shouldn’t (value_1 + value_2 + … value_250)/250 be used instead? I.e:

return (CurrentValueAvg);

Used a 5v Pro Trinket because it was what I had and already had it working with the LCD. Was a while ago but have a vague recollection of a firmware change or at least thinking about it.

Yes, the averaging looks weird and something I’m tackling with a rewrite when I get a minute. I agree though, thought it looked strange myself when typing it.

The 1.22 isn’t volts, is just a multiplier. For 9mm G2 diodes it’s thought the power in watts is current X 1.22. Source is 2nd last paragraph: http://jtechphotonics.com/?p=1379



Thanks, Ian. I thought I had read that page a few times but I never made it down to the conclusion :smiley:

Btw, I assume the 5V Trinket would work as well without any fw change on the laser driver, but with (34%) less granularity. I.e. if the output of the laser driver is in the range of 0~3.3V and the analog input pin of the microcontroller can receive 0~5V, then instead taking advantage of all 1024 quantization levels, you would be using the first 676 (3.3*1024/5).

Indeed, granularity was the idea but now you’ve asked I’m racking my brains as to whether I actually dealt with the difference as I cannot remember.

Want to sort the averaging anyway so I’ll do it all then :smile:



anyone actually touch the laser by accident? just curious as to what it would do. I’m sure it would burn it but would cut off a finger lol

Haven’t had the fingers near the laser while it was running so I can’t share the details. Obviously I wouldn’t recommend it. I have seen some ugly pictures of folks who had the 40w laser burns but not the 2.8-3.8w burns