[svanommen]

Hello Zone,

I love my Gecko G540 but I have a quandary. Currently all 4 ports (Z,X,Y,A) are all in use as my A axis is slaved to my X axis and I want to add a 4th axis / rotary table. [link in my signature offers details about my CNC gantry router if needed]

So I'm wondering how to best go about this. My initial idea is to add a second parallel port to my computer + break-out-board + G250x or similar driver. As I recall Mach3 can handle a second parallel port (if configured properly).

Or . . ?

What sort of issues might the above idea encounter (if any)?

Thanks!
Seth

[smdysmf]

I just did that exact same thing and everything went very smoothly.

[svanommen]

Excellent! Thanks for the heads up smdysmf!

[smdysmf]

I changed my slaved axis to B in mach3 and used A for the rotary head.
It seems like cam programs like to use A for the rotary axis.

[Op4]

Did you guys have to use a charge pump on the 4th axis? The G540 already has a charge pump for the other servos, but I was wondering if one was needed with the G251x and BOB.

thanks

[dmauch]

I have built several 5 and 6 axis cnc control boxes using the G540 and 2 G251. Therre are a couple of issues. The most inportant problem is the G540 uses an enable function and the G251 uses a disable function for outputs. To solve the problem I use a DPDT switch. One side is hooked up per the G540 manual to ground and the other is opposite.
Relative to the charge pump issue, you could add one from cnc4pc.com but you probabaly really don't need it if you make it a habit to bott up the PC first then turn on the control box.
The other issue is you power supply. Will your power supply have enough current to run all 5 axis ?

Dan Mauch
Camtronics, inc. -- CNC with Dan Mauch