The great thing about the 40W Chinese lasers you can get on eBay is the price. For what you pay, the quality of the core components is surprisingly good. The laser tube and power supply are fine. The optics (mirrors and lens) are fine. It’s really only let down by the quality of the surrounding bits. Wires may be loose. Screws may be missing. Alignment may be off. The table to hold the workpiece is bizarrely small. The Moshidraw software is an abomination. However all this stuff can be change to turn your £500 laser into something you might have to pay 3-4 times the price for.
The first improvement to the laser had to be to ditch the Moshidraw controller board and software. I’d heard so many bad things about it that I decided to replace it straight away. I’m proud to say that I’ve never even installed Moshidraw.
I replace the board with one from ChrisCircuits. It’s basically a parallel port breakout with a couple of Pololu A4988 stepper drivers. However, Chris has done an excellent job sourcing the unusual connectors and making it a swift drop-in for the Moshiboard. There were a couple of tweak to be made to make his V1.1 board work in place of a V4.1 Moshiboard, but he documented these well and it was easy enough to do. Now I can conrol the laser using CamBam (for design) and Mach3 (for CNC control) and I’m right at home. This is the same toolchain I use with my CNC mill.
It wasn’t completely smooth. I was surprised to find a female connector on the board rather than the male on on my TB6560 mill controller. An annoying delay whlist I ordered a male-to-male DB25 cable. I also had to cut out a slot in the side of the machine that was big enough for the cable. The little USB opening wouldn’t cut it.
The X axis didn’t work at first but it turned out to be nothing more than a loose cable. I meticulously worked out how many steps per millimetre I needed by meausing the belt pitch, counting the teeth on the pulley and checking the microstep setting on the driver. I calculated it at ??. Way out. By measuring how much travel there was it turned out to be 79. Oh well. 79 it is. No idea why.
The only things that were missing from Chris’ installation instruction were on the homing settings. I had to tell it the the X axis homes in the negative direction and set the X and Y coordinates for the home position (0 and 220). I suspect I may have a different version of Mach3 to Chris. [To do – add details.]
Anyway, here’s the obligatory “first cuts” video.
Does this controller vary the laser PWM duty cycle (beam power) with travel speed as the head accelerates or is it simply on/off?
It’s only on/off. There’s plenty of scope for improvement on these machines but they’re a good starting point.
Doing some research on a problem I have with my Chinese Laser, I found a post on the CNC forum where you rashly offered to help with a similar problem to the one I think I have, if the guy lived near Redhill…
Is that offer still open? I can come to you from Chertsey.
Yours, with thanks
I dropped you an email to the address WordPress linked to your comment. Let me know if it doesn’t get through to you.