How to. 2 or more motors on one axis. Gantry

Gruntled Raptor wrote:

I'm guessing the only situation I would be making alteration to the firmware is if it was changing core functionality of pins.

Exactly.
And even for that in some cases there is no need to flash the cards, any unused stepgen/PWM/ecnoder counter frees up the pins as normal IO.

but XYZA axis machie A have angular and use degree joi t , not linear, now working right. maybe better if linuxcnc builders has make basic option to setting wizaed, because here have option XY,XYZ,XYZAm foam,lathe,customm but why not have normal most used XYYZ. totally idiot has write linuxcnc code, if not have double YY option in basic software.
i has try make double Y machine last 2 month but alltime not working, if dual motor working not can homing, and not can move both Y to same time, home ,and not can move any axis minus only plus side. and Z not working anything. i not know how make working dual Y machine, maybe not possiple at linuxcnc. debian10 2.8.4 version. waste lot money build linuxcnc maybe need mova all to trash and tell my son not can building software have idiot make.

how setting dual YY if not have owerprice expensive mesa shit card ? normal user use cheap chinese paraller port breakout board not expensive mesa trash, normal hobby user not have budget buy super expensive mesa.

A couple suggestions:

1. Add a LinuxCNC issue about stepconfs lack of gantry support:

github.com/LinuxCNC/linuxcnc/issues

Hint: insulting LinuxCNC developers that work for free is probably not a good strategy.

2. Read the beginning of this thread that includes instructions for modifying the hal and ini files
stepconf creates to support gantry configurations:

forum.linuxcnc.org/49-basic-configuratio...cnc-2-8-master#96594
 

It isn't really all that hard to set up a dual joint driven axis using parallel port controlled stepper motors. You don't have to have Mesa hardware. But why all of the vitriol about Mesa card pricing? They really are a bargain for what they are. For example when was the last time you tried to purchase a dual parallel port PCIe adapter card? A new one, if you can even find one that works correctly with Linux (about half of the ones for sale on the internet don't) costs almost as much as a Mesa 6i25 (at least here in the States.) The $20 dollars more for the Mesa card is a small pittance to pay for its added capability.

Also as Peter pointed out read the beginning of the thread.  I'm pretty sure instructions for this are also in the documentation.

I'm not sure about in version 2.8, but in version 2.9 the Stepconfig wizard does have support for creating a tandem motor driven gantry axis.  You set it up as a usual 3 axis machine in the 2nd window (choose XYZ) for the Axis Configuration.  Then on the Parallel Port 1 (or 2...) configuration window assign 6 parallel port output pins for the step motors so that you have X, Y and Z, Step and Direction, plus set up two more output pins for Tandem Y Step and Tandem Y Direction.  You will also need to configure two input pins for the Home-Y and Tandem-Home-Y. (or some of the other appropriate combined home/limit options).  Then complete the Stepconfig setup.

It is possible this support also exists in 2.8. (I don't currently have 2.8 installed somewhere to easily check.)