3:1 puller for PET bottle recycling

prusaprinters

When I first assembled my Petamentor I noticed that even though the puller was screwed to the motor it sometimes can skip. After some tinkering I noticed that even with a 7rpm motor (JGB37-520 12v 7rpm) I can't lower the speed enough to get a smooth, consistent sizing (probably due to my Flinstone-level tech and tooling knowledge). In order to overcome these I've decided that I will further slow down the process and also increase torque with gears. I took a look at Petamentor SS but didn't wanted to buy additional hardware for the puller so I was started to plan a design on my own. I've decided that a 3:1 speed reduction might be enough for me and after a couple of iteration I came up with this design. From hardware wise I was using the following:  - For the driver gear:    - 1 M3 nut    - 1 M3x8 screw  - For the idler and driven gears:     - 2 M8*60 Screws as axles    - 4 M8 nuts    - 6 M8 washers    - 4 8*22*7 (608 2RS) bearingsFor the reel and the spool I've used M3 heat inserts and M3 screws (sizes don't really matter, the longer the better, I was using M3x10 and M3x12.Be gentle with the M8 nuts, you don't want to overtighten the bearings, just tight enough that the axles can have a bit of a play, but not too much. Depending on the method of cutting (I think I'll switch to precut the bottles as my cutter seemingly has some kind of issue with some bottles) you might see that sometimes you need to need to adjust the tightness of the M8 nuts. Might worth looking into some threadlocking solutions, but overall no real issues so far. Posting the FreeCad file to enable remixes (eg. for different motors). As an added feature: the spool contains slots where you can push in the first couple of cm-s of the filament to lock it on the spool, I really liked that idea on the ReCreator.