19.7mm PTFE Jig for Bondtech MK3S Mosquito Extruder

The Bondtech MK3S Mosquito Extruder requires a 4mm outer diameter 19.7mm long PTFE tube if you are using the new Mosquito v2 hot end that has the wider and shorter heat break (dark colored heat break). 

Bondtech includes a 19.7mm PTFE tube with their full extruder kit, but doesn't include one in the housing-only upgrade kit. With this jig, you can easily cut a PTFE tube to the proper length. It's not a fancy jig, but it works and prints fast.

Instructions

1. Print at 0.2mm layer height ONLY.
2. Place PTFE tube into cutting jig, all the way to the left. Depending on your extrusion calibration it may be a tight or loose fit.
3. Grip the jig firmly but place it down on a non-slippery surface. I purposely designed this jig very small to print fast and store without taking up much space and I don't want you to slice your finger open.
4. NOTE: If your PTFE tube is loose fitting and not snug in the jig (like Capricorn PTFE that has a slightly smaller outer diameter) I highly recommend applying pressure onto the PTFE tube from the right by holding the whole unit up against a wall or ledge when you cut in the next step. If you don't, the PTFE may slide when you make the cut and give you wrong length.
5. Use a razor knife to cut the PTFE in the slot, applying pressure downwards while making back-and-forth sawing motions very carefully until you have cut all the way through.
6. There is a hole in the left side of the jig to help you eject the PTFE tube. You can fit either the large hex key that comes with the Prusa kit in here or a flat head screwdriver, and push gently. Be careful not to deform the PTFE.
7. Remember you will still need to chamfer the opening of the PTFE tube on the top side (step 4 of this link) that the filament feeds into. The bottom side needs to stay flat. Whichever end of the PTFE tube that looks flatter should NOT be the side you chamfer.

Because of different extrusion calibration, your print may not cut it exactly 19.7mm but it should be really close. If it's not nearly perfect, then scale the STL on the X-Axis only in PrusaSlicer by 2x the amount in MM that it was off by. So for example if this cuts your PTFE tube to 19.6mm instead of 19.7mm, scale the part on the X-Axis from 28.9mm to 29.1mm (a 0.2mm increase).

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I like to modify my printer parts, trying to make them better. Take a look at some of my other projects and designs:

MK3S Y-Axis Motor Mount Ultra
(improved Y-Axis motor mount with better shaft and nuts)

MK3S Z-Axis Tops Improved
(Less vibration and easier Z-Screw Alignment)

D.R.O.P.P.E.R. - PINDA Adjustment & Positioning Tool
(Achieve the perfect SUPERPINDA position)

MMU2S Single Filament Guide Festo M5 Coupler
(Retain your original MK3S spool mounting while still using MMU2S in single color mode)

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https://www.patreon.com/photogad