PicoMMU 3-lane ECAS hub

This 3-lane hub is a modification of the orginal from LH's github. It adds in space to install an ECAS bowden tube collet to allow for easy mounting to an existing extruder assembly without modifications. In my case it allows me to keep my orbiter smart sensor in place as a visual filament detection and status mechanism.

When assembling this part, take note of the recessed area in the base of the hub. This is to allow the bowden tube to seat past the ECAS collet. I've found that this reduces the chances of the filament snagging on the ECAS collet and causing a failed filament load. 

When installing your bowden tube, I recommend giving it a slight twist as you push it into position to ensure it seats into the recessed area in the hub. As long as your bowden tube is cut perfectly straight it will butt up against the exit past the sensor, and should allow for a perfectly smooth transitional point between the hub and the tube.

I strongly advise against using a long tubing run from the hub to the extruder unless you have a filament buffer. Try to keep the tube as short as possible, as its length will directly affect the retract distance that the MMU needs to run to be able to clear the filament from the hub.

Additionally, you will want to measure the distances between sensor and extruder gears to ensure that you don't have failed load/unloads, as this hub extends your stock extruder to sensor distance drastically.

On a final note, if you find your hub doesn't retain the bowden tubes too well while loading filament, you could try what I'm doing with mine wherein you print one of the PTFE tube spacers (available in the extras section on the PicoMMU Github), install this to the tubes, then bind it together with zip ties or fishing line. I used the latter on mine and so far it's working extremely well… So well in fact that on my previous revision of this hub, the ECAS Collet lost its grip before the spacer did!