Carton 100mm f/13 "MD" OTA Construction - GSO Focuser-to-Main Tube Adapter Attachment
 

Marking where the holes will be drilled for attachment of the focuser to main tube adapter followed by the GSO Crayford focuser. (Click to see an enlarged image.)

 
With the GSO focuser-to-main tube adapter in its final position, the holes are carefully marked in preparation to drill the holes to attach the adapter to the main tube. Done properly as much as the tube was cut accurately, the focuser will align accurately with little to no collimating once it is installed.