PTFE Tube Chamfer - Pencil Sharpener Style

prusaprinters

When I came to needing to make a new hot end PTFE tube, I tried all the chamfering jigs I could find. But I couldn't get the hang of holding a blade in a jig and then turning it, or the tube, to get the chamfer. The only thing that worked for me was a pencil sharpener, but then the hole was to big and the angle was wrong.So, I came up with this design. It takes a standard pencil sharpener blade, and there are three available fixing holes so we can use the blade three times in different positions. I do hope there is a universal, international standard for pencil sharpener blades.I first designed this with the blade on the left hand side of the cutting edge, and it worked fine for me. But I then noticed that this is the opposite of a regular pencil sharpener. Why? I thought - maybe it's because I am left handed in lots of things, so I made a version with the blade on the right hand side of the blade as well. if I were you I'd visualise which you'd prefer and then print that one - they only take an hour or so to print.There are two angles, 120°and 60°, both in a left hand (LH) and a right hand (RH) version.PLA is fine, best in fact, since it's less likely to string. I used 3 perimeters to give the m2 screw something to bite into. At 15% infill, the 60° takes about an hour and the 120° takes about 95 minutes to print. I've used a heavier infill, just to give it a bit of weight - a personal preference.You'll need one pencil sharpener blade and one m2 screw, between 6mm & 10mmIf you use an existing pencil sharpener for the blade, you may be able to use the screw from it as well.Before you attach the blade make sure the hole for the PTFE tube is completely clear of any stringing and debris. The blade will attach easier if you pre-thread the hole with the screw.In use - (I use the LH version) - hold the sharpener in the right hand, rotate it and feed the PTFE tube with the left hand - it just needs a little feed inwards and then hold it steady with your thumb and forefinger while you continue to rotate - it's pretty intuitive after a bit of practise. Pretty much like sharpening a pencil.Then cut the PTFE tube to length afterwards.Enjoy your PTFE sharpening!