XXL X/Y Extents

I decided to install the CM .364 Build tonight and start exercising my new Turlen Dial indicator. I want to know how true my custom T-Nut’d wasteboard sits in refernce to Z heights.

The CM Rapid Positioning utility is a great way to move about the machine bed and get some good measurements, When I click to position along the most negative, left X position, the Z carriage smacks against the left side rail (this after successful homing) and chatters for a few cycles.

My question, are the current 850mm X/Y extent correct, or does this need fine tuning?

I jogged mine manually from the home position until it was almost to the left end plate, then used the distance shown on the screen that it traveled. So I used 838mm (32.9921 inches) rather than 850mm.

Thanks @dtilton71 -

Thanks for your confirmation.
Fine tuning it is as you describe.

I have mine set to 830.

I am having the same trouble. I first had my extents set to 850 and 850, all was well. Now for some unknown reason, every time I go to any of the LH side Rapid Positions the gantry will hit the rail. I have tried adjusting the $130 to everything from 830 to 850 with the same results, like the setting is not taking. Have turned off the machine, re-homed, etc. Anybody else?

Set my extents to 833/853 respectively