BondTech BMG Filament Tube Guide

thingiverse

This is a 3D printer filament tube guide that mounts vertically (at least on my printer) with the flare on top. There is a 2mm hole on the bottom that the filament feeds into the guide. The guide holds a PTFE (Teflon) tube with an outside diameter of 6.36 mm and inside diameter of 3mm. The top is flared so that the PTFE tube doesn't get kinked. It is mounted to the side of the printer using two M5 low profile screws from OpenBuilds. The second piece mounts above your extruder on your X carriage with a second piece of PTFE tube coming out of the top flange. You only need 150-250mm of the PTFE tube for each piece. As the X carriage moves away tube guide on the side of the printer, the filament pulls the PTFE to a more horizontal position. As the carriage moves closer to the side mounted guide, the PTFE relaxes and lifts the filament up, away from your print and some of the filament gets pushed back down the side mounted tube, outside of the printer, away from your print. This works surprisingly well. I've never had a filament problem with this system. <a href="https://youtu.be/F5zvo85cbbY">See it working here.</a> I use the <a href="https://www.bondtech.se/en/product/bmg-extruder/">BondTech BMG extruder</a> on my X carriage. I made the extruder mount from 2mm thick 6061 aluminum. The edge of the extruder mount ends at the side of the NEMA 17 and is extended up above the extruder. The printed extruder tube guide attaches to the extruder mount with two <a href="https://openbuildspartstore.com/low-profile-screws-m5-10-pack/">Low Profile M5 screws, like the ones from OpenBuilds</a>. The two M5 holes are centered 19mm apart horizontally and 25mm vertically above the M3 holes for the NEMA 17, but they are not vertically aligned with the M3 holes. If you make your M5 holes exactly as described above, the 2mm hole in the bottom tube guide will perfectly line up with the opening of the <a href="https://www.bondtech.se/en/product/bmg-extruder/">BMG extruder</a>. You can put a very short piece of 4mm O.D. PTFE tube (about 6mm long) in the top of the extruder so that it sticks out only 1mm above it. Chamfer (taper) the top inside of that short tube so that the filament will never get caught on it, no matter how curled it is. The 2mm hole in the bottom of the extruder tube guide should be resting right on top and centered above the short 4mm tube you just tapered. You will have no trouble loading new filament into your extruder. It will go right down to your geared pulleys every time without even having to touch the quick release.