CNC lathe to grinder.

Greetings. At my work place, we recently acquired a CNC converted lathe running Knuth LinuxCNC 3.4.6.

There's a few changes we need to make for it to suit our needs. First was to set it so it would home near the chuck. I already moved the homing dogs and the limit switch orientations corrected the saddle direction so it homes out near the chuck as desired. I do understand this homing orientation is the opposite of what's commonly done on a lathe. The reason for this is the lathe is being converted into a grinder for urethane rollers. In this case we need to have the saddle home near the chuck to prevent having to move (or crash into) the tail stock so it can home every time we need to home it. We're replacing the chuck with a collet head with an internal stop for repeatability (provided our cores are to the desired spec, but that's another story)

I'm still familiarizing myself with LinuxCNC and despite my best efforts so far, I seem to have hit a wall. The issue I have is although I have it set to home safely near the chuck side, in the preview grid the position marker moves in the opposite direction. The saddle moves right the marker in preview moves left. Prior to setting XZ to X-Z it would try to travel off the grid altogether and soft stop would attempt to prevent it from moving beyond the preview boarder. You can see it in the image I attached how X & Z are positioned near the lower right of the grid. Is there a way to get the preview to place Z on lower left of the grid? 
Thanks in advance.

 

I will get this posted as soon as I can. Thank you.

Please read the post fully to understand why this is necessary.

This should be it.  

I knew it had to be something simple I was overlooking. I'll give this a try. Thanks for the explanation.

Hmm. It appears it won't allow me to do that. LinuxCNC terminated with an error.