Hello again, I'm still struggling with obtaining smooth movement from the laser head on

Hello again,

I’m still struggling with obtaining smooth movement from the laser head on my CNC. This is not a mechanical problem. It is due to the planner/data transfer rates or browser not keeping up with the CNC machine.

I’ve tried changing the number of lines uploaded, and the delay time to send the data, but I just cannot get the settings right to get a continuous smooth movement of the laser head from start to finish.

If I upload too many lines, the browser stalls and becomes unresponsive until the uploading is finished. The laser head stalls during this time, but then it becomes a little smoother after the upload completes, but by then the damage has already been done. This means I have to complete uploading the data by the time the laser head reaches its first cut. This limits me to around 1000 lines maximum (unless I slow the head movement right down until it reaches the first cut). This does not seem to be the right solution though…

I have downloaded JSON 1.95 Serial Server, but this has not helped solve the problem.

The really strange thing is that everything was working perfectly well a few days ago. I repeated the same cut on several occasions (just played the same G-Code around 15 times - each cut takes around 20 mins). The first few cuts were near perfect, but towards the end, the movement was so bad that the laser just blew through the material all over the place instead of creating a clean smooth cut.

I have read through the instructions to understand the number of lines / multiple lines, and delay times to send the data and believe I understand whats happening here, but does anyone have any step by step checks to assist in finding the best figures for a particular set of problematic G-Code lines…

Thanks in advance…

Update: If I upload 1000 lines of code to start with, and transfer 50 lines every 2 seconds, the Port shows a figure around 1000 lines all the time until it completes and the counter runs down. So, If I understand things properly, I constantly have around 1000 lines in the buffer which is updated every 2 seconds with an additional 50 lines, but the laser head still stops and starts regardless… Any ideas how I can smooth this out? Thanks

What machine do you have SPJS running on? What CNC firmware are you running? SPJS is very fast at sending to a CNC board, but if your CNC board runs out of moves in it’s planner buffer, it can get choppy. One suggestion on your initial upload process, put an M6 tool change pause at the start of your Gcode after maybe a slight X move of 1mm back and forth so that ChiliPeppr tosses up a pause/unpause notice when your CNC machine hits the M6 line. That way the laser would have never turned on until after that M6 pause, but you won’t see the pause until you’ve uploaded the whole file or a large chunk of the file.