[bitmannz]

Hi

I have a client who has bought a microcontroller board off me to try and develop a 2 axis control system. I have tried to convince him to go with the pc but he insists to stay withthe microcontroller for reasons unknown to me.
I was wondering, would there be sufficient demand to develop a 'box' that plugged into the parrallel port and recorded step and dir commands as a sort of macro so that a user could just plug it into their cnc hardware and use it without the pc direct?

Many Thanks

Bruce

[HayTay]

bitmannz,

That sounds like an interesting device. I don't know how much demand there would be for it though. It would be a great little device for someone that had multiple machines so they wouldn't have to have a dedicated PC for each. I could see someone like Joe2000che using one to control his CNC router for when he's cutting out his Joe 2006 parts. The ability to store multiple jobs would be a plus in his case. All of the component cut paths could be stored in one box then selected via an interface comprised of a few buttons and an LCD.

The box would have to be 'intelligent' enough to be able to process homing, limit, e-stop, etc. signals from the machine as well as the captured step and directions instructions generated by the PC.

You may want to develop this project along a DIY type of path. Instead of selling the completed units, sell the plans, code and component kits. Just a thought.

Keep us apprised of your progress if you decide to go ahead with this project.

[bitmannz]

Thanks HayTay

The easy part is the step dir stuff, Tell me is there any documentation on the homing and estops etc.

If you had buttons to move your toolhead '+/-' in xyz axes then a button to 'set home' as well as an 'estop' button/input to halt the tool movement and cut power to the tool head while maintaining its place in the code.

What happens if you estop a job midway with a pc cnc rig? does the pc remember where it was or is it a start over

Regards

Bruce

[Jay C]

You may find some answers to your questions in the Using Mach3Mill guide here: http://www.machsupport.com/documentation/

But my understanding is that the switches are hard limits. The Mach3 software will allow you to set soft limits as you are describing. Also, the EStop kills the drive and spindle power (depending on how it is wired) so the resulting position can be guaranteed (think of machine momentum). Thus the answer is no, the PC has no idea (other than the last command sent) where the machine is/was. However, Mach3 does allow you to start the job from any line of G-Code, so if nothing was damaged then you can just pick up where it left off.

As for this project, the G-REX project is a more sophisticated version of what you are trying to do. It can take commands from Mach3 or a microcontroller to control motor drivers. Have a look at www.geckodrive.com for more information.

Also, this reminds me of the Sears CompuCarve commercials I keep seeing. You program a memory card on your PC then insert it into the machine. I don't see too much difference in flashing the AVR versus writing to a flash drive ... do you?

Jay

[bitmannz]

I'm not certain but I think that flash memory will tolerate many more write/ rewrites than the avr. Also there may be ocassions that the memory on the avr may be insufficient?

[Jay C]

My point was that there is at least one commercial precedent. Also, there external flash readers you can interface with.