[Swansea Hackspace] An old PC with parallel printer port?

[Graham Owens]

Perhaps i am missing something still, but how exactly do you control these things without a pc? I understand the how of toggling pins etc, but i mean the practical aspect of actually setting up the machine and running it?

Ho for example do you do a touch-off on an arduino controlled cnc?

> On 17 Sep 2014, at 12:38, Justin Mitchell <justin at swansea.hackspace.org.uk> wrote:
> 
>> On Wed, 2014-09-17 at 11:44 +0100, Justin Mitchell wrote:
>> So after we have jury rigged one using a standard arduino, we can then
>> mill the pcb for a custom made one :)
>> 
>>> On Wed, 2014-09-17 at 11:39 +0100, Gerrit Niezen wrote:
>>> It seems a solution appeared on Hackaday the same day that you were
>>> discussing the problem:
>>> http://hackaday.com/2014/09/16/usb-to-db25-adapter-uses-grbl-for-parallel-port-cnc-communication/
>>> 
>>> 
>>> Guess what: It’s Arduino-based and runs GRBL.
> 
> This also seems to apply to laser cutters, at least the cheap ones with
> parallel port connectors. They appear to be the same level of dumb
> step-stick style driver inputs that many CNC machines are.
> 
> So a cheap laser cutter could be adapted to work (the supplied software
> is notoriously bad) without even changing the electronics.
> 
> Further research has shown that these cheap cutters tend to have two
> control boards, one is the psu, and connects to the safety interlocks,
> the HV laser tube drive, stop switch, etc.  this in turn gives 5v, laser
> trigger, and motor drive voltage (24V?) outputs.
> 
> the second board is then the stepper controller / interface board,
> theres often just two steppers X/Y, end stops, and the TTL level laser
> on/off trigger, which can be driven with PWM for finer control.
> 
> So replacing the stepper controller with something more modern is going
> to be pretty easy if you need to, but if its a parallel port one you can
> just as easily put an arduino with GRBL/Marlin on the outside and get
> the same level of control.
> 
> 
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