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ERCF v2 -RC1 (Community Project) Build


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Well, because I just love building things – here I go again – ERCF V2 (Community Project).

Having just finished a TradRack and having the kit for a ERCF V1 (Fysetc), I looked at the BOM and decided to acquire the additional hardware for the V2.

Downloaded the Parts Tracker – it is an essential aid to help maintain your sanity during the printing process. As I had the two Voron 2.4’s spooled already, I just decided to go with those colors. Polymaker Polilyte ASA yellow as the accent color and Polymaker Polilyte ASA Red.

Read the manual /build guide – that took a while – 147 pages of it. Because I at times have a couple of minutes to spare at work, I have both the web-manual/build guide and the manual in the source file open. (And there seems to be differences in the two editions).

Build Instructions:

Pages 1- 17 Introduction:

Tip: Print all the tools in the tools folder – you are going to need them all.


Some important information and clarification of part naming (a)_ , (mm)_, (c)_, (o)_, etc explained firstly. Important because the encoder slotted wheel needs to be printed in black. Printed this with a 1.2mm layer height and at 50% of my normal speed. 

It also indicates why some parts have dagger †, next to the name. These are parts you can reuse from your ERCF V1 build. I won’t recommend this as your printer tolerances may have been different at the time you printed those parts. If you are going to build a V2 – it would be best to re-print everything. so that's what I did.

First step – recalibrated the first layer and confirmed the extrusion multiplier as per the Ellis guide for the filaments. Printed the calibration block, made some flow adjustments, reprinted the calibration block – think I am ready to go.

Page 15: Started by doing all the heat set inserts, as I find it is easier that way and I can get along with the build. Came across the first discrepancy between the web manual/build guide and the downloaded manual.



Page 15 on the web manual:



Page 15 on the download manual:



The web has pages 95,105,132,138 listed for parts needing inserts, but the downloaded PDF has pages 96,106,133,139 listed. I can confirm the latter is correct. Somehow the numbering got mixed up between the documents.

No big deal if you are following the manual page by page and not doing all the heat set inserts all at once.

For the rest of the build, I will be referring to the downloaded manual that was part of the zip file downloaded.






Heat set inserts went smoothly and I was glad I had the Stealth Insert Press, as this made the job so much easier, especially with the heatsert of the selector cart (p85) – it’s down in a hole.

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All heatserts done and ready to get on with the build.

Next Selector Motor.





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Pages 18 – 23: Selector Motor and LED wiring:

Two options here:

1.     Using your existing octopus board as the controller. (Remote MCU)

2.     Using a dedicated controller board such as the Easy Brd of BTT MMB (Local MCU) This is also the recommended option. 

Note if you are using the BTT MMB, your ERCF end support arm for the buffer, will be different to the other support arms,  as it incorporates the electronic box to mount the BTT board. If using the Easy Brd board, the support arm will be the same as the other 5. I initially input EasyBrd in the parts tracker and that made me print the standard support arm. It is only as the build progressed that I decided to switch to the BTT MBB. The reason for this is that it has enough end stop ports for the cotton tail buffer. (just a hint for those that love to print everything in advance like me.)

BTT MBB – End Support arm                                                                                                            Standard Support arm

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Instructions for both options are very similar except for the length of the wire to be cut.

As there are so many variants of the Molex plugs available, I decided to test fit the connectors I had, to the motor arm. Surprise-surprise – No slots for the Molex connectors to fit into. It appears the Motor Arm designated for the Easy BRD board DOES NOT have the microfit connectors slots.


Motor_Arm_NEMA14_EASYBRD.stl.            vs               Motor_Arm_NEMA14

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Mmmmhhhh. Re-read the manual again – answer on page 43. The Easy BRD mount is for the local MCU option (Easy BRD / BTT MBB) and the one with the fittings is for a remote MCU. Makes sense thinking of it – If you connect this to your octopus board (Remote MCU) you would want an easy way to remove the connections. If the MCU is mounted on the unit, this is not necessary. No reason not to do it, depends on preference. But following the parts tracker - I printed the EASYBRD options.




Why do I always overthink things? Just follow the instructions. It says: Motor wires to be cut and Molex connectors crimped for remote or local MCU. Just do it! Selector Motor = 200mm, Gear Motor = 500mm. No I won’t as I do not like cutting wires in advance (Measure thrice, cut once), so I skipped this step. Will cut and crimp the wires when I get to attach it to the mcu (local - BTT MBB0.

The same logic was applied to wiring the LED’s, though the manual does say that the preferred method for the strip LED’s (as in the BOM) is:

“The suggested method is to stick the segments of LED strip to the inside of each of the Cover_Body_xN, attach all of the Cover_Body_xN to the 2020 extrusion, and solder short pieces of wire between the strips.”

Will revisit these when I get there. But I had the jig printed already and just had to try it out – great design – sure this will make soldering these so much easier. Note this jig is only for the individual LED’s (as used in the Stealthburner), and NOT the strip LED’s from the BOM.

image.jpeg.b63d528428aa23d13b02d161458e29d7.jpeg                 image.jpeg.04446c48885561958962fc71024065de.jpeg


Next: Gearbox







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Pages 24 – 51 Gearbox.

First mishap of the build – overtightened the screws onto the extrusion and cracked the “gearbox front” – another excuse to print something, so no great loss.  Fitted gearbox front and back to the extrusion after the reprint.



One point to remember and it might be a logical step for those experienced builders but remember to solder on the wires to the Omron switch before assembling the above. Will be much easier than trying to do it later and save you from stripping the build down again. Once available, I suspect the kits will have all switches pre-soldered with the correct length of wiring.



80T gear assembly: - I love jigs – so easy, and accurate.

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One thing to note, is to spend time in getting the 80T gear correctly onto the shaft, tensioning the screws (alternate screw, bit by bit) to ensure there is no “wobble” (p38). I did not do this diligently enough initially, and after assembling the gearbox, found the 80T gear rubbing intermittently on the gearbox back. Went back and revisited the “wobble” issue – re-adjusted the screws - no more rubbing.

image.jpeg.c7d5b97fc9f3570ce62558d018e9df80.jpeg   image.jpeg.1955827badd3feff2128269de7b8b5cf.jpeg

Next Filament blocks




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Page 51 – 69 Filament Blocks.

There is some preparation to do for the parts, as all parts are printed with build-in supports. Take your time removing these.

Lubed up all the bearings from the bondtech set and inserted into the tophats.



Used the printed jig and installed the base bearings. How easy was that!

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If the manual is followed, this is a straightforward assembly. However, I did ensure all the holes for the filament path was clean and the filament moved through the blocks without resistance prior to assembly.



Filament blocks completed.

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Next End Block



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Page 71 - 77 End Blocks.


Pretty straightforward. No issues or pitfalls. Starting to look like something now.




Pages 79 - 93 Selector.

First the fitting of the linear bearings into the encoder housing. These are a tight fit, but the good old Knipex did the job just well. The BOM lists both the LM8UU (steel) or the RJ4JP-01-08 (plastic). I had both and after doing a bit of reading on these, decided to go with the LM8UU as the Igus website states the RJ4JP-01-08 bearings must be secured with a circlip. Whether it is necessary for this build, I don't know but decided not to change it.



Used the savox servo and when mounting it to the servo holder, stripped the head of the screws supplied with the servo. (The manual suggests using this.)  Problem is that it was only halfway screwed in and there was no way of removing it without destroying the part – looks like  I can print something again.  Reprinted and fitted the servo with some 2X8mm SHSC I had in my arsenal.

The next challenge was the spring cap – where is it – sure I printed all parts. Well let’s print again. Took a full 2 minutes to print and now I know why I could not find it. Must have thought it was part of a support structure or something and thrown it out– it is tiny. (6mm to be precise).



Now trying twisting that into a stiff spring with fumbly fingers – all that twisting reminded me of the 70’s on the dance floor – “Let’s do the twist”.  



Got it - finally!

Selector done.



Next Encoder






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Pages 94 – 102 Encoder.

The importance of good tolerances in your print parts comes in to play when fitting the printed black encoder slotted wheel to the BMG Idler gear. Luckily there is a jig for it and it worked like a charm. I also used the V623ZZ bearing(slotted) as per the recommendations.

Still need to install the tiny 3X2 neodynium magnets that keeps the door locked onto the encoder body. – awaiting delivery.

All assembled without much issue

(Part resting on one of the jigs – looks like a horse)



Next Linear Axis.


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Pages 103 - 112 Linear Axis.

Easy assembly, lightly lubricated the LM8UU bearings, ran the belt and cut with 10mm excess as indicated in the instructions.



Next Final Assembly

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Pages 113 – 124 Final Assembly.

Well lack of attention strikes again. Inserted a M5 locknut the wrong way round and cracked the plastic part whilst tightening the screw. Too much force applied as the locknut was inverted in the part and the screw could not progress – Getting fed up with reprinting stuff now, especially so close to the end. But it is my fault and mine alone. 


Wasn't happy with the quality of the part in any case - maybe it is my excuse 🙂

On with the build…. 

Reprinted the motor mount and this time inserted the locknut in the correct orientation. Fitted the carriage to the filament blocks, adjusted the rods to length and fitted the cable chain.

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Next in the manual is the wiring – P125 which I will leave till last as I am incorporating the BTT MBB in the cotton tail build and would need to mount this first before starting to cut any wires.

Next:  Cotton Tail Buffer

Will be a bit of a hiatus before my next post. Thanks for reading along. Till next time



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Beautiful presentation.

Because you have already done the undo-able version 1, tuned the hell out of it, the tradrack, you already know how these things work. I guess most people that start building these things have no idea how a MMU functions 😉

The filament blocks, that you showed off here in just 3 pictures, was for me the hardest part to build and to understand. In fact, I printed the stls for these from the v.1.1 github. Then I downloaded and printed some from 'Triple-Decky'. There were so many parts to put together just 1 block, I also got Thumper blocks and printed them out. Now I finally know how they work 😉 I know, slow learner...

I had not seen the definitive parts tracker excel sheet (just pre-release versions), it really nicely and completely integrates everything out there, simplifies a whole lot of studying the endless documentation. Prevents printing a directory and then seeing you do not need half of the printed parts. This will again give you the opportunity to 'break' or 'screw up' parts you just printed and reprint them.

I am curious how the tuning process will go this time. What binky and the filament cutter will bring you.

Have you decided where you want to put the cutter? Sensor? 


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11 minutes ago, Dirk said:

Have you decided where you want to put the cutter? Sensor? 

Have decided and printed the dual sensor CW2 and filametrix as a start. May change.

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Pages 128 – 143 Cotton Tail Buffer

Where the manual for the ERCF was rather detailed and clear, the same cannot be said for the Cotton Tail Buffer.  I would suggest reading these 15 pages a couple of times. 

The sequence is to build the arm groups – set them aside.

  • Build the coupler blocks – set them aside.
  • Solder the omron switches to each other – set them aside
  • Solder the LED’s – set them aside
  • Build the end arm – set it aside.

Do not try and assemble of fit assemble at this point.

Soldering up the microswitches – the length of the wire required is IMPORTANT – else it will cause binding during assembly. The lengths are given in the manual – 70mm for the connection between the switches and then varying lengths from the switches to the control board as per the manual. (I would suggest going an extra 10mm = 80mm, as this will ease installation later on).

I have annotated the diagram to make it easier to understand.



But being cautious, I cut all the lengths to 200mm – will trim them down during the wiring phase.

Soldered all the omron switches together and ensured continuity throughout the chain. Despite my best efforts, still managed to break one of the connections when assembling the buffer. I use a plastic electrical paste insulation rather than heatshrink, therefor the bare contacts in the photo.



Arm and Mount:  Had to reset a couple of heatserts that was inserted literally 1mm too deep and prevented the mount to sit flush with the arm.

At this point, there is no need to do anything else once all the arms have been united with their mounts. Do not assemble the arms together as you are going to have to take it apart again.

Coupler Blocks:  These should be printed in an opaque material for the full LED effect. I may reprint these at a later stage, but for now will use the one I have.

First point is to ensure the hole for the 5.5mm ball is clean and the ball moves freely, and the filament path is clear.

Just out of interest – when I initially test printed the coupler blocks, I found all the holes were flattened on one side. Changed the seam position form “aligned” to “random” in Orca Slicer and the issue resolved itself.

I had to slightly clear out all the holes in the blocks, to ensure free movement. Next, I tested each coupler block for function by attaching the omron switch and running a piece of filament through it to ensure it triggers the switch.


Attaching the ECAS colletts may cause an issue if you are not careful. Firstly, you need to remove the rubber seal from the bottom of the connector.



Now the cap needs to be attached to the body. Normally I would insert the body in the part and press fit the cap against a flat object using the part to force down till it seats.


  • The coupler blocks are hinged and if pressure is applied may break
  • The ECAS assembly requires quite a bit of force to assemble. 

I tried assembling this on the coupler but was afraid to apply too much force on the coupler that would have ensured the blue part to seat into the grey, resulting in a broken coupler. Decided to pressure fit them outside of the part, then attach them afterwards. 

I damaged the first one as I used the trusty Knipex to press fit the blue bit to the grey bit. By doing this, I crushed the plastic part where the rubber grommet attaches (Grey in picture but black in mine). Removed this part and successfully press fitted the blue connector to the grey body. 



Cut the PTFE tubing to length (6 pieces in my build) and insert into the coupler. This is necessary for the final assembly.

(Again, there is a jig to cut the PTFE tubing to length – 48.5mm)


LED’S: There are two ways to attach the LED’s

  • Apron LED’s that utilises the strip LED’s that need to be cut into individual parts or
  • The individual LED’s as used in the Stealthburner. 



The printed parts for these options differ and if you look at the manual for the buffer, it only shows the mount for the individual LED’s.

However detailed instructions on installing the strip LED’s can be found on the github page.

Although I had the strip LED holders printed and individual LED’s cut, I made the decision to use the individual LED’s rather than cutt strip LED’s. Printed their holders and trial fitted it. Soldered the wires using the supplied jig.




Inserted all the LED’s in their respective holders, and set it aside once again.

Added the assembled chain of omron switches to the coupler blocks, ready to be attached to the arms as we go along.

Started assembling the arms onto the extrusion. This was a bit of a challenge as I was paranoid of breaking off the soldered connections. All went well with the assembly.



image.jpeg.80bd60ac580e1e7678dd84e80aefecaf.jpeg     image.jpeg.ecb14dd45ba3da61cf8e0bd40ba34ec9.jpeg

Added the LED's

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Added the BTT MBB controller Board

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Next wiring....

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Wiring: pages 125 and 140

A lot of crimping. Glad I left the wires uncut and not follow the manual's recommended lengths,  as it was a challenge routing the wires in the controller box. The lid snap fits and the wire needs to exit at the top of the box, else it won't close.

Only used this diagram from the manual for the wiring:


The end result:

IMG_5825.thumb.png.8127776625786e9bd0bad9d71982e1ec.png     IMG_5823.thumb.png.ad3c6f72a70434bb68a40c3701a2c4c5.png  IMG_5824.thumb.png.b7752207b6286d254cf4d0b30144d1e9.png


Next Programming - when I have the time for it as I like to dedicate a full day - keeps my mind task orientated that way........ but first some family time this weekend - it is a long weekend here in Australia and time for some fun on the lake, boating, kayaking, swimming, relaxing and some fishing in Bonnie Doon.

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Again a lot of work well done. Looks beautiful. 

I must be honest, the btt can board seems very handy. So many wires...

The ercf v2 Looks like a miniature version of some kind of kermis attraction 😄

Enjoy your weekend!

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8 hours ago, PFarm said:

Again thanks for taking the time to make this detailed post. Are you using both sensors in the tool head? 

I will be yes. Have printed the parts, just need to assemble. May do a build diary on Filametrix - just have to see if time allows for this. Also now have a selection of small round ball bearings, I was confused initially with what size to get. The ERCF uses 5.5mm but although filametrix's BOM says 5.5, some users on discord have noticed that a 7mm works better. Then I have plenty 4mm left over from tradrack. Can start playing mini-marbles. 

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@mvdveer I have the D2F-5 with the roller lever but I think I can remove the lever. I also assume that they are wired N/O but can be reversed in software. 4mm for Tradrack Damm I though I ordered all the parts I was missing guess I missed this one.

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7 hours ago, PFarm said:

@mvdveer I have the D2F-5 with the roller lever but I think I can remove the lever. I also assume that they are wired N/O but can be reversed in software. 4mm for Tradrack Damm I though I ordered all the parts I was missing guess I missed this one.

That will do, as you do not need a lever arm, I have used D2F-01L and removed all the levers - do not think it makes much of a difference whether it has a rolled or straight lever..  They are wired NC as per the manual (Page 136). And the 4mm ball bearings are for tradrack, not ERCF, it uses 5.5mm. The Filametrix, I started last night uses 5.5mm.

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On 1/23/2024 at 4:04 PM, mvdveer said:

Have decided and printed the dual sensor CW2 and filametrix as a start. May change.

I am looking at the same setup but am not finding any instructions outside of the readme. Am I missing them somewhere?

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1 hour ago, jutjut said:

I am looking at the same setup but am not finding any instructions outside of the readme. Am I missing them somewhere?

No you are not - I just did a mini build diary on it. Basically follow the CW2 instructions in the stealth burner repo.

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1 hour ago, jutjut said:

That's what I was thinking. How did you wire in the switches? Do you have a toolhead PCB? If so what ports did you use?

Have not done any wiring of the filamentrix as yet. Will wire the switches as NC. I will be using a BTT SB2209 canbus board and had a look at the wiring connections - this should accept the additional two end stops.

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39 minutes ago, jutjut said:

Do you have a toolhead PCB

This is interesting.

I believe the ERCF v2 is designed to work without CAN. or any other toolheads.

If I am not wrong, the happy hare software / firmware handles a lot of the pushing, pulling, servo'ing, sensing and cutting. Kind of an add on to Klipper. 

The hardware part that does the selecting port, filament, sensing should be going over the ERCF board (the EASY BRD board or any other replacement from a Chinese company for it). Also the sensing of the filaments in the filamentrix should be connected to this board. Of course I am probably wrong, because I did not read the manual 4 times. But ERCF can work perfectly well without Filamentrix. But (at least) a sensor at the extruder is is recommended by the manual / happy hare software.

Also the original HartK 2 piece board for the SB, has an AUX port meant for the 'ERCF'. (there is a rabbit drawing on the card I bought).

Anyway... Thanks again for all the insights and walking the dark path for us @mvdveer so we can follow in your trail 😄


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1 hour ago, Dirk said:

I believe the ERCF v2 is designed to work without CAN. or any other toolheads

True, but the recommended board for the ERCF v2 is the BTT MBB board that is a Canbus board. However there is the option to connect it directly to the printer controller board. It is all about choice. As I am using sensors at all the gates, I need 7 more end stop connectors, therefore the MBB board. The two sensors on the hotend are optional but will make it easier and more reliable filament swaps. These can be connected anywhere there is a spare endstop pin.


1 hour ago, Dirk said:

Also the sensing of the filaments in the filamentrix should be connected to this board

Not necessarily as the software determines the function, not the hardware. You can connect these anywhere as long as you define the pins in happy hare software

1 hour ago, Dirk said:

 But ERCF can work perfectly well without Filamentrix.

It will also cost you days in tuning filament tips (I have done that and know the frustration involved) To have it work perfectly means tuning each individual filament to perfection. Cutting the filament eliminates tip tuning for individual filaments

It is all about choice: Canbus vs HartK, Tip tuning vs Tip cutting, Remote mcu vs local mcu, Umbilical vs Cable chain, LED's vs no LED's gantry backers vs no gantry backers, trident vs V2.4, etc, etc

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