Filament Cutter for EVA3, Orbiter, Rapido

***Update: Aug 18, 2025*** Added left side cutter. This was actually the original way I did it and was unpopular in the discord during development due to widespread superpinda use at the time. Obviously with the cutter on the left, the super pinda cannot be used. I was asked to add this option so I have uploaded it here. This version is untested, so if you use it, please advise me in the comments if there are any issues. Specifically the interface with the servo pushblock may not be correct.

***Update: Jan 22, 2024*** Added ptfe tube mounting instructions for eva3 with filament cutter at bottom of description

***Update: Dec 12, 2023*** Revised cutter_macro.txt with some improvements and bug fixes.

***Update: Dec 4, 2023*** Added a servo mount for enclosure 2

This is a filament cutter for eva3 with orbiter and rapido models. It is used in multi color single extruder setups such as ROME, ECRF or others. It allows for any type of filament to be used, without any need for tip form tuning. It creates a much more reliable filament swap leading to less failed or paused prints in multicolor because the molten portion of the filament never fully leaves the hot portion of the hotend. It will also allow for quicker filament swaps since no tip forming is required. The actuator is mounted on a ds3235sg (or similar) servo which allows for the push block to be tucked out of the way when not in use, so no reduction in bed printable area is required. 

For hardware:

Blade: https://www.amazon.com/dp/B0B8FYY77H?psc=1 a #4 hobby blade, cut to 28mm long. Use a 3mm dia set screw, 3mm long to secure the blade to the printed blade holder.

Spring: I used a 8mm O.D. x 19mm long compression spring with 0.6mm dia. wire. But anything relatively close will work fine (but don't go over 8mm O.D.) These types of springs are widely available in any hardware or home supply store.

The best way to install the ptfe tubing into the eva3 filament cutter mount: 

Assemble the eva3 mount (while it's off the printer) with the filament cutter assembly fully installed.  Please make sure the cut blade is installed such that it's fully flat surface faces upwards toward the hex hole in the hotend printed mount, while it's chamfered surface faces down toward cold part of hotend. But do all of this without the hot end or orbiter mounted. Then put the ptfe tube in from the top of the orbiter printed mount, with it sticking up too much from where the orbiter mounts and also sticking out past the bottom where the blade is. Then mount the orbiter pressing the tube down as you install it with it's two screws. This should take a fair amount of force, as the hex hole in the printed hotend mount should be tight on the tubing. If it isn't reprint the part with a higher flow rate. This ensures the tube is fully inserted into the inside of the orbiter exit tube (metal part). Then cut the ptfe tube with the filament cutter blade (support the loose end of the tube so it doesn't bend way from the blade), but do this with the entire assembly upside down, so the blade doesn't sag downward. This ensures the tube is flush with the top of the blade. Make sure the blade doesn't bind against the tubing, move the blade back and forth until it moves freely (recheck this after assembling the entire hot end). Now take more tubing and install it into the unmounted hot end, and after fully inserting it, cut it flush with the top of the hotend (cold part) using a flat razor blade. Finally use a tool (drill bit or tapered hole cutter) to flare out the entrance of the ptfe tube on the hotend, creating a small funnel in the tube. Make sure no ptfe particles are left in the hotend, hold the hotend upside down when flaring the tube and tap the hotend on table before turning right side up. FInally install the eva3 fully with hotend and orbiter mounted, onto the printer. This will require some disassembly and re-assembly during the process, sorry.

Important note for orbiter2 extruders. Many have been shipped with the exit tube too far away from the hob gears, this can lead to jamming during color swaps. Before installing the orbiter, tighten the exit tube until it hits the gears, and then back off a ¼ to ½ turn.