[Chugalug] Driving a 3-axis TTL stepper mounted router

basic2point0 at gmail.com basic2point0 at gmail.com
Mon Nov 18 22:06:41 UTC 2013

If it’s any help to anyone, I work as a CNC machinist. Lathe, mill, grinder, router table, laser router, we have all that stuff. I borrowed software from work way back when I started at this particular place, so that I could install it on my own machine and play around with it, because I didn’t have time for experimentation at work.

I have Mach 3 (registered) in  a Windows 2000 Virtualbox  vm that someone could play with if needed. 

From: Jason Brown
Sent: ‎Monday‎, ‎November‎ ‎18‎, ‎2013 ‎4‎:‎54‎ ‎PM
To: Chattanooga Unix Gnu Android Linux Users Group

I have a little experience.

At Chatt*lab we have a 4'x8' CNC router doing exactly that. There are a LOT of ways to get to where you want. A lot of it depends on the size of your machine, final goals, and what hardware you already have. It sounds like you already have stepper drivers and a power supply so you just need to interpret g-code into stepper pulses.
It is a BIT more complicated than that if you want any decent performance though, acceleration, home switches, soft and hard limit switches, tool offset calculations, etc etc.

I recommend LinuxCNC to get started, you probably have something lying around that will work:

If you want to control directly from a PC:
    Forget using USB to parallel ports, there is too much latency. Driving steppers needs precise timing and a real-time kernel in Linux or Windows XP.
    Use a real parallel port. There are still pci is pci-e parallel cards available. Laptops have issues due to their power saving functions.
    Get a parallel port breakout board for your wiring. I use this one and like it a lot: 
    It says USB, that is just for power.... 

The Linux Way: (What I am doing).
    LinuxCNC: http://www.linuxcnc.org/

The Windows way: (More costly of course)
    Mach3:  (Good software, trial version is great for small parts and testing but is limited to 500 lines of g-code.) 

If you want to use a dedicated driver board I hear the grbl stuff is great, but I have not had a chance to try it out yet.  For experimentation, the LinuxCNC route is more flexible, but more complicated.  For a production unit or something I were selling, I would go with something grbl based.
    Recently one of the developers / inventors of some nice grbl based hardware visited Chatt*Lab and we discussed his products at length. https://www.synthetos.com/ I plan to buy a couple for experimentation with a small CNC mill and lathe soon. 

I'm happy to discuss further, or show you the stuff I have running down at the lab sometime.
-- Jason

On 11/18/2013 04:31 PM, Dan Lyke wrote:

Friend has a router mounted in a 3 axis table, with enough circuitry to
drive steppers from TTL inputs. He was writing his own software to
drive this thing.

Friend is kind of a neat freak and doesn't like how much sawdust it
generates in his garage. I have graciously offered my workshop.

What I'd like is the quickest easiest toolchain possible to drive this
thing from Linux.

I note that Inkscape has a bunch of plug-ins which can generate gcode

So I *think* that what I need is something that'll either give me a USB
parallel port, or take USB in in a way that I can feed it gcode, and
that'll give out TTL pulses.

Right now the leading choice seems to be installing
http://dank.bengler.no/-/page/show/5470_grbl on an Arduino 328.
However, if anyone has experience on setting up the full toolchain for
this, I'd like to save the couple of hundred bucks of wrong paths I'm
about to go down...

Anyone done this and got input?

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