BETA CYCLE IS COMPLETE - RELEASE IS NOW FOUND AT THE OFFICIAL ERCF V2 PAGE: https://github.com/Enraged-Rabbit-Community/ERCF_v2

Cotton Tail buffer system will attach directly to the Sturdy Bunny upgraded ERCF and is designed to work with any number of filament blocks you choose (the initial test phase will go up to 9).

The primary goal of this project was to reduce as much resistance in the path and to remove any inconsistencies in calibration. It works with Triple Decky but will work with whatever top hat/filament block design you want. In fact, there is no limitation to the design, and it also may remove the need for magnets in them altogether. There is a spring in the couplers to alleviate all pressure on the magnets.

This system is also designed to reduce the buffer length, which will help reduce friction on the entire system. There will also be optional QoL features to work with the new BTT MMB Can board. Features:

• Large central buffer wheel - reduces the filament's natural shape - each wheel comes pre-notched to make loading filament easier.
• Inline connection - connects to the 2020 extrusion arm
• Short Buffer Length - Can operate as low as 500mm in buffer Length
• Reduced resistance - Tests up to 200 mm/s (with Galileo 2 extruder) - may do less or more depending on your extruder motor
• Improved encoder accuracy - makes all resistance more consistent for better encoder performance and less torque needed
• Stackable Arm - Each arm is stackable for whatever combination of gates you want. They are optimized for strength and weight and provide access for loading and unloading filament
• Uses most parts from ERCP - if you already have a kit, most parts should be interchangeable.
• Filament Detector - Each coupler has a filament detector built in. This is optional and will interface with the new BTT MMB Can board.
• Filament indicator - Future QoL option that will include the ability to light up each gate to tell you if it is loaded/active and empty/out of filament.

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BOM (Each arm group/channel):

• (8) 8mm M3 screws
• (1) 16mm M3 screw
• (1) 25mm M3 screw
• (1) M3 threaded inserts (M3x5x4mm) Heat Sets
• PTFE Tubing (4mm OD/3MM ID recommended)
• (1) 608 ZZ Bearing (same as ERCP - skateboard bearings will work as well)
• (1) ECAS
• (2) M3 Hammerhead T-Nuts (for attaching to 2020 extrusions)

End cap (with integrated MMB CASE) needs:

• (6) 8mm M3 screws
• (5) 25mm M3 screw (1) for non MMB
• (4) M3 threaded inserts (M3x5x4mm) Heat Sets (0) for non MMB

The optional MMB version build requires:

(1) BTT MMB Can board (1) Microswitch per arm (1) 5.5 mm ball bearing per arm (2) 12mm M2 BHCS screws per arm (1) Button Neopixels per arm

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Building the ERCT

Instructions

PRINT SETTINGS

.25mm first layer, .2mm Layer Height 4 Perimeters (top, bottom, walls

Arms should be printed at .2 layer height, with 4 walls and 10% lightning infill. This will significantly reduce the amount of filament used. ABS is the recommended material or PETG.

Wheels should be printed on a smooth plate, or if you use a textured plate you may need to run it on some sandpaper afterwards to avoid too much contact with the arm. There will always be a small chance of some rubbing, but with careful pressure on the hubs when installing, you shouldn't have any major resistance.

The rest of the parts can be printed with 20-30% gyroid infill.

	Start with your printed channel arm and add a 4 mm-deep M3 heatset installed into the back of the arm. Be careful not to go too far past the dovetail channel- it's better to be shy than to go over.
	Print the correct length axial screw. The files are labelled for how many channels. They are longer than needed in case you need to put a bypass divider or extra support. Use the matching nut and work it through the acme screw to make it smooth. A brass brush can also be used to clean it up a little. It is recommended if you make more than 9 channels, to self-source a trapezoidal bar screw (also known as ACME screw). T8, Pitch 2 is a common one. You can also use a traditional screw. Make sure to get matching nuts to add to each end for those builds.
	Load the axial through the first arm.
	The 608 bearings should slide in with just a tiny bit of resistance.
	Make sure the filament loading holes are as pictured, and load the axial from the flat side of the wheel.
	When pushing down on the axial, put your thumbs on each side of the bearing and push down with moderate force. Don't push too hard. If it doesn't go on, use a little sandpaper on the axial to reduce it. It is a tight fit but should slide on. Your pressure on the bearings will ensure the wheel is as balanced as possible. There's a very tiny bit of gap between the wheel and the side of the arm. Don't worry too much if it isn't perfect, but you can try to balance it and spin it to check.
	Preload the M3 Hammerhead T-Nuts onto the mounting bracket. Don't screw in too tight as you need to turn the nuts easily to load into the v-slots of the 2020 extrusion.
	Load the mount onto the arm. The dovetail is snug but should slide on with some pressure. Once seated add the M3 16mm screw to secure it.
	Squeeze the printed spring (the spring goes towards the ECAS side) and slide into the slot on the sloped side.
	Add ECAS fitting in the hole. It should snap-in and firm press.
	line up the coupler as pictured to the three receiving pins. It should press fit with a small bit of resistance. Repeat the next channel arm until all is loaded.
	When you reach the final channel, you will add the end cap and install the final M3 25mm screw.
	Secure all 6 screws, which enter at an angle. They self-tap into the plastic, so don't over-tighten or you'll strip the plastic. These install and reinstall multiple times if you don't over-tighten.
	The next step is prepping the ERCF. If you have wiring clips, remove them and free all your wires.
	Line up the t-nuts as best you can. Make sure you didn't wind them all the way down. The screws should have enough friction to hold them in place to make this part easier for you. It should sit right on the shoulder and slip in. If not, jiggle the arms a little; it should all mate perfectly. Grab your driver and turn, and it should tighten right away. If not, back off a quick half-turn and turn the back the other way to load the nut in place.
	The last set of steps starts by cutting around 85mm of tube which should leave around 10mm of tube sticking out of the coupler block.
	Insert the cut PTFE tube from the rear of the assembly. Push lightly in the spring, and it should feed through.
	Line up to the channel and press into the ECAS on the filament block.
	The rest of the tube can be trimmed to around 10mm.
	The wires can now be routed against the mounting brackets and you can use zip ties to secure it.

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LOADING THE BUFFER

	To load the buffer, filament from your reverse Bowden. Try your best to work with the natural curl of the filament and feed it till you see it pop out on top.
	Grab it from up top, and curl it back into one of the multiple filament loading holes located along one side of the buffer wheel.
	Turn the wheel until you have the number of rows needed for your tube length between the ERCF encoder and the tool head (to calculate the right length, measure the tube and divide by 230mm. This will equal the number of rows you need to wrap around the wheel - maximum of 7).
	Back below, grab the filament on the wheel and pull it out.
	Give yourself some length (about 30 cm).
	Feed back into the tube located there.
	It will feed through, and you should feel some resistance from the trap; press on the top hat to help it through.
	The final step is to push the filament flush to the opening so it doesn’t catch on the selector. That’s it. Load it all up, and away you go!