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cgallery
07-06-2003, 02:18 PM
I purchased a small, partially completed CNC router table. The mechanicals are supposedly all done (I haven't received it yet), and the motors (steppers) are mounted. It is up to me to wire the motors to driver(s), add a power supply, and perhaps wire some limit switches. Basically, I have to do all the wiring and tuning.

I would like some sort of integrated driver which will work via the parallel port, support the three stepper motors, perhaps have limit switch input(s), and work with a variety (two or three) software packages which are readily and cheaply (:-) available. I realize this is a tall order, I'm hoping for suggestions.

Many of the commercial CNC routers I've seen don't refer to limit switches, so I have no idea how they know where they are. I do need limit switches, don't I? One for each axis?

I'm not sure where to get started. Any suggestions would be greatly appreciated.

Thanks,
Phil

balsaman
07-06-2003, 02:57 PM
Hi,

Try the xylotex board www.xylotex.com It has everything you need, and is priced right. Run it on a 12 or preferably 24 volt power supply.

You don't NEED limit switches, but you can add them. Usually home switches is all you need, so that's one per axis. Thy mount on the axis at an end of the travel here you would like the home position to be. I located mine such that the router was up, out of the way for easy stock placement.

If you want you can also have over travel switches, which stop the machine if it travels to the extreme mechanical end of any one of the axis', so you need 6 total for this. I didn't bother.

Hope this helps.

Eric

cgallery
07-06-2003, 04:56 PM
If I don't have limit switches to determine home, then how does the CNC controller know where to begin? I want to cut holes in precut pieces of MDF, but the holes must be centered. I had assumed I was going to put a jig on the table to hold the pieces securely, "calibrate" the software so it knows where the center of my piece is in relation to the home switches, and let it do the cutting? Does this sound reasonable?

Now, the XS-3525/8S-3 Stepper board is the one I assume you were referring to? The notes on the web page don't mention limit switches. Do I need something additional?

The "Xylotex Stepper Indexer" on the same page seems to refer to limit switch inputs. However, this isn't a driver in the technical sense, it seems, but an interface to additional driver(s)?

BTW, do the CNC software packages out there all support limit switches? Do you just tell it what pin the limit switch is on and it takes it from there?

Sorry for all the questions. I really appreciate your help.

Thanks,
Phil

cgallery
07-06-2003, 05:06 PM
I read the PDF on the Xylotex unit and it refers to J10 which is often used for the limit switches. How does one gang three different limit switches to one input? Once one limit switch is reached, wouldn't the software believe all the limits have been reached?

Thanks,
Phil

balsaman
07-06-2003, 05:07 PM
You can move(jog) the machine with the computer to a location (for example the bottom left hand corner of your stock), then zero all the axis, and start from there.

I don't have a xylotex, so I am not sure about limit switch inputs. I am sure someone who knows here will pipe up soon.

Yes all the software I know of supports limit switches. Yes, you tell it what pin its on and that's it. Simply send the machine home, then run your gcode from there.

Eric

kong
07-06-2003, 05:54 PM
I have the xylotex board, and it is excellent, even better with a 24v power supply. You can wire the home switches in parallel, and use three inputs, that way your software will no which axis is at home. As for the limit switches, they should be wired in series, therfore all switches only take up one output, but the software will not know which axis tripped the switch. It's no biggie though, only the home switches are important as, like Balsaman said, once a limit switch is tripped, all action is stopped until you manually jog the machine away from the collision.