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

Jason Brown lists at masterforge.com
Mon Nov 18 21:54:22 UTC 2013


I have a little experience.

At Chatt*lab <http://www.chattlab.org> 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:
http://www.ebay.com/itm/USB-5-Axis-CNC-Breakout-Board-Interface-Adapter-For-Stepper-Motor-Driver-/321133023129
     It says USB, that is just for power....

The Linux Way: (What I am doing).
     LinuxCNC: http://www.linuxcnc.org/
http://wiki.linuxcnc.org/cgi-bin/wiki.pl?LinuxCNCKnowledgeBase

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.)
http://www.machsupport.com/software/mach3/

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
> toolpaths.
>
> 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?
>
> Dan
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> Chugalug at chugalug.org
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