I too, have a 3" belt sander Model no. 315.11720 that runs like a champ. BUT it needs a new sanding belt, and I would really like a copy of the manual. I wrote to *****/Craftsman and requested a copy of the manual, however "Unfortunately, ***** no longer has a manual available for this tool.".
I would really like to use this tool, if you have a copy could you post it?
Your post is old, so don't know if this will reach you. I'm a retired lady who needs to sand a door, so my son-in-law helped me buy a Craftsman 3" belt sander, Model No. 315.11720 at a pawn shop, then went back to Alaska before he could show me how to put the sandpaper thingie on.
Were you successful in finding an instruction manual for your sander? If so, could you share how you did that?
......with the cord unplugged........use your body to push the sander's FRONT ROLLER against your workbench (or wall or door jamb)......the roller/frame will move and offset.....catching on a pin holding it in the "Open" position......
Install the correct sanding belt .......in the correct direction and tap the front roller on the workbench (or with a mallet).......the roller will release from the pin and automatically tighten.......With the cord plugged in .......use the knurled screw to adjust the belt to run true........
"...measure once.....cut twice....throw that one away and cut a new one...."
Take tension off belt by placing front pulley (wheel) against floor or workbench and giving a big push. Replace belt with arrow in clockwise direction. Retension by placing tip of flat headed medium-sized screw driver against the box housing in center (where the ID plate is attached) and the shank of the screwdriver against the horizontal plate that holds the front wheel. Give the plate a push forward and it should snap back into tension mode.