Foam Cutter - XYZA vs XYUV

Hello all,

My configuration is for a 4 axes form cutter.
Side 1: X is Horizontal, Y is vertical. Side 2: U(Z) is Horizontal, V(A) is vertical.

When I set it up as XYZA I convert the A axis to linear and all 4 axes are set the same.

I am using limit switches and home is at 0 with all the limit switches -0.1 inches past home.

When I "Home All" in this configuration everything works fine. X and Z home to the limit switches and back up to 0.1 inches after the limit switches open. Then Z and A do the same thing. When I load and run the test g-code file and run it the machine goes through all the motions of cutting foam.

I got my head bloody on the keyboard trying to get the XYUV configuration set up correctly but kept getting "joint 6" errors, etc.
Then I found the XYUV hotwire configuration topic in this category and used it to get to where I am now.

When I launch my-xyuv setup I get the Z error message because the Z axis is missing but I don't care for now, I think. When I load my g-code file the display looks reasonable for the file I have. It is the same as above with Z and A replaced by U and V.

As soon as I do a "Home All" the X and U motors head for the limit switches. Whichever gets there first caused a limit switch/joint error and it stops. No attempt is made to back off of the switch and go the 0.1 inches like the XYZA configuration does.

Any ideas of where I should look? I am probably missing something obvious but I have stared at the configuration files so much that they sort of blur right now.

Any help, suggestions or pointers would be greatly appreciated.
I have attached the two sets of configuration files that I am using.

Thanks again.
Ron Oehler

There is a full simulated XYUV hotwire config in the samples, sim->axis>axis_foam. If you select that you can fiddle about with it in simulator mode, and it will copy the sample config to your LinuxCNC directory.
Have a look at the axis_foam.ini file and see how it is laid out, it has

[DISPLAY]
...
GEOMETRY=XY;UV
FOAM=1
...
[TRAJ]
...
AXES = 9
COORDINATES = X Y U V
...
[AXIS_0]
{real stuff}
[AXIS_1]
{real stuff}
[AXIS_2]
{minimal dummy stuff}
[AXIS_3]
{minimal dummy stuff}
[AXIS_4]
{minimal dummy stuff}
[AXIS_5]
{minimal dummy stuff}
[AXIS_6]
{real stuff}
[AXIS_7]
{real stuff}
[AXIS_8]
{minimal dummy stuff}

Your INI ought to look very similar.

You will also see that each real axis contains (amongst other things)
HOME_IGNORE_LIMITS =
...
HOME_IS_SHARED =

You probably want HOME_IGNORE_LIMITS = YES in your config, and possibly HOME_IS_SHARED = YES if the limit switched for each axis share an IO pin.

Thanks for the quick reply, Andy.

Now that the weekend is over and I am back at the machine I was able to pursue the problem again.

I finally found it in the xyuv.hal file.

Here is the fix: The commented lines were the problem.

setp stepgen.2.position-scale [AXIS_6]SCALE
. . .
# net min-home-u => axis.2.home-sw-in
net min-home-u => axis.6.home-sw-in
# net min-home-u => axis.2.neg-lim-sw-in
net min-home-u => axis.6.neg-lim-sw-in

and

setp stepgen.3.position-scale [AXIS_7]SCALE
. . .
# net min-home-v => axis.3.home-sw-in
net min-home-v => axis.7.home-sw-in
# net min-home-v => axis.3.neg-lim-sw-in
net min-home-v => axis.7.neg-lim-sw-in

Now to get rid of the 'Z' axis error on startup.

Thanks again.

Ron