Camera selection

need help to know what lens for camera will be mounted 15 to 16 inches above bed bed size 200 by 300 and hope to sometime increase to 300 by 600 on k40

If you are using Lightburn software then check out this link:-
The 5mp - 160 or 5mp - 140 camera should work fine. Most K40’s have feeble, flexible doors you will need to add another support stay opposite to the original. Depending on your machine you will probably have to mount the camera externally on the outer lip of the door.

got camera it has 90 degree lens and i have mounted it 18 inches above bed and 14 inches above bed and i cant see all the bed in the overlay view no matter where i put camera in live view i see more then bed size almost all the machine how di i adjust what you see in the overlay view so i can see all the bed

You will need a 140 or 160 degree lens to solve the issue as they give a much wide view and will cover the whole bed.
Hope that helps.