First a correction on what I told you earlier. Since you are using a fixed camera and fixed grid you will need to select a 1 plane calibration, Projecting=Perspective, Override focal distance=yes, Dist=focal length of your lens. (In order to do a 2-plane calibration you would need to mount a target on the EOAT. This works very well if you can do it, & no manual touch up required!)
I can grasp the calibration gird and hold it perpendicular to the camera if I actuate the wrist up 90° but I wont have the z reach to get anywhere near the part surface and I would have to refocus to be able to see it at all, I only get about 4" of z travel I don't include the wrist and EOAT. I may be able to come up with some sort of angle bracket and keep the EOAT pointed down (the orientation I use it). I set the focal distance to what made the Z accurate on the position of camera relative to calibration grid come out accurately. My lenses are zoom lenses with focal distance from 6cm to 15 cm, the value I set was 8.9mm which seems accurate.
I try to get my grids perpendicular to the camera axis, but depending on the accuracy you need, it may ok, you just need to test it. If you are worried about loosing resolution by moving the camera farther away you can always go with a longer focal length lens which will "zoom in" on the image. How far off from perpendicular are you and what lens are you using?
The issue is I can set the cameras to be perpendicular but doing so moves the area I'm interested out of view, I can zoom out and just use one corner of the image and keep it perpendicular but I cant have it both perpendicular and zoomed in because the robot arms will physically crash with the cameras if I put them directly over the area of intrest. If I could re mount the robot backwards and if the XC-56 had its cables coming out the side instead of the back I would be able to shove the cameras up and straddle the back arm but that's not really an option I have.
I would redo the calibration this way, leaving the camera where it is and see how good your accuracy is before changing the camera position. Make sure to set your Z height in the vision process tool!
I think I'm going to* make a copy of my calibration grid so I can cut it out and fit it down directly on the pic area (right now its about 5cm up).
*Update, after doing this it now picks up all parts nearly 100% of the time except for one corner where it never picks them up, and they are always off in the same direction.
What would be the best way to correct for this, can I add custom points in the grid calibration data, can I edit that data (other than deleting points)?