Chinese CNC 3020 / 6040 - USB variant

Hehe, curtisa! Is Mach3 *that* bad?
That's quite peculiar, that they'd deliver a cracked copy...

Good hint, maybe it's true and they don't have real USB. At least on the china ebay sellers' offers I saw, their info wasn't laid out very well, I found it somewhat hard to follow / figure out what's what. And they all seem to share that.
I won't even complain that their spindles reportedly have "8000 rpm / min" (acceleration?) and anti backFlash mechanisms which apparently produce long life circles.

Hehe, curtisa! Is Mach3 *that* bad?
That's quite peculiar, that they'd deliver a cracked copy...

Mine was certainly delivered that way. I've seen other people on the internet say the same thing. It was just a burnt CDR with some poorly translated instructions about how to enter the provided unlock code for the Mach3 installer. I didn't bother.

My experience from using a 3020 for a few years was that for the money it's a good little entry-level unit. You'd be hard pressed to make something from scratch for the same price. I do note that there appears to be two versions floating around. The one I got was this one. I don't know how well the other one stacks up. It will mill/engrave PCBs, plastic and wood quite happily with the right cutters. I milled aluminium twice on it, but it definitely struggled doing it.

David Suffield of Eckler Software has done almost what you are looking for- he's extracted the GCode interpreter and trajectory planner of LinuxCNC (or EMC2 as it was when he started) and pythonised it as PyMini, and added his own hardware for the realtime functions- a PIC based PCB called rt-stepper that implements the realtime bit, and you can attach direct to a D25 connector, or direct to stepper PCBs etc if you have the energy. They aren't very expensive ($30-100 depending on model), but for us cispondians the postage adds a big chunk to that.

It's diverged a long way from LinuxCNC, and isn't half as good to look at, but it shows that LinuxCNC doesn't have to be tied to the realtime kernel, and that when LPT ports and PCI slots finally disappear, all the good work on the non realtime part (i.e. everything but the bit that pokes the motors) doesn't have to be wasted.

Since he has correctly retained the GPL2 licensing and made the source code available, it should be possible to rewrite the USB functions to work with the Chinese interfaces - IF you can find details of the USB protocol used. Being Python, it's pretty well OS agnostic.

About the usb machine controllers, i have something to say.

3 years ago i had ordered a usb controller for mach3. but it was dangerous to use.
(5 Axis USB CNC Motion Controller, Mach3 Breakout Board for Stepper Motor Driver) i see it is no longer available.

1. It lost connection to machine when you use it not for 30 minutes or longer. After that machine is not controllable anymore and machine was shaking. So pressed emergency brake.
2. The usb controller can't make torch height control. So for me no usb controllers in the room please. :blink:

I had a hardware unit which may have had bugs, and I used it with some software which may have had bugs. It failed wrong- side. Therefore any hardware used with any software is dangerous. I think there could be a flaw in this argument somewhere.

What is the future of Linuxcnc if it is never planned to support USB.
A PC with an installed Parallel port would now be in excess of 15 to 20 years old and built on pre Pentium architecture. The idea of running a machine on a PC built from a scrap yard makes no sense.
Ok there is limitations but suerly a git fork could be created for a USB version even if it was limited in functionality.
GRBL works ?