The spool mount is made to be easy to take spools off when done and replace them quickly. The spool itself has printed ends which fit into a 6″ length of 2″ Shcedule 40 PVC pipe. It’s easy to make as many as you need at home, and they are made to fit smoothly onto a 3/4″ PVC pipe.
Start by cutting two pieces of 1/2″ MDF to 16″x8″ and glue/screw them together at right angles. Drill an 8mm hole about 7″ from the base, and 1″ in from the left side for the threaded rod.. Use a spade bit to drill another hole 3/4″ wide about 1″ down from the top and 2.5″ in from the left edge for the motor arm. Cut a section of threaded rod about 9″-12″ and put it through the hole with a nut and washer on each side of the board. Slide the spool stop against the nut on the front of the board.
The spool stop looks like a cylinder with a hole in it, but it is actually shaped like a small spool. There is a single thread wall (.42mm wide) around the edge to act as support, which should be cut away. This will be used later on along with a screw to keep the mount from sliding off when you remove a spool.
The Class 200 3/4 PVC pipe has an ID that is slightly larger than a 608 bearing. If you wrap about 2-3 layers of electrical tape around the outside of the bearings it will make a snug fit. Place two bearings on the rod far enough to provide good support for the spool, with a printed washer and nut on each side of each bearing. The nut of the inner bearing should also hold the spool stop in place. The washers will let you tighten the nuts against the bearings without restricting their motion. You can save time threading the nuts on by using a drill to spin the rod.
The mount for the hall effect sensors is also pictured, but that will be added in later when the electronics are done.
Cut a section of pipe long enough to reach the end of the spool and slide it on over the bearings, up to the end of the spool stop. Slide the spool gear onto the pipe with the flange pointed toward the back board, flush with the end of the pipe. With a 3mm bit, drill through hole in the flange, through the pipe. Put a M3 16mm screw through the hole. This screw will bump against the insides of the spool stop and keep the pipe from sliding off when you remove a spool.
There are four small holes in the gear. Drill them out to 4mm and put 3 M4 18mm bolts through them, with nuts on the other side. The bolts will slide into matching holes on the spool to lock it in place, and the nuts keep the spool back far enough that it doesn’t drag against the motor gear.
Print Lyman’s gear motor arm and washer and mount them in the 3/4″ hole. Use M3 screws to attach the gear motor and slip the small spool gear onto the motor shaft. If it is too tight, drill it out with a 6mm bit. If the motor arm was a tight fit into the hole, you are done with this part. If it is a little loose, you will need to hook a small spring to it, with the other end screwed into the back board. If the gears are not held tightly together, the motor will be pushed away whenever the filament gets a little hard to pull. If you want the spool to spin freely, simply lift the motor up.
There’s more to come, as I can get it written.