TradRack Encoder simple adapter and EREC filament cutter

Background

MMU TradRack doesn't have encoder and filament cutter.

there are already some mods for encoder and or cutter for tradrack, however, too many parts to manage to print, quite confusing. every parts are modded and different from the original design.

I want to make a simple adapter solution, to decouple things as much as possible, just to make the design simpler, to manage and print as less parts as possible. 

Design Main Target 1 - Encoder

Using a adapter to use the existing ERCF(v2) encoder, without modding encoder case, and not to remake and modding everything again when not necessary. easy to print and replace and install.

Design Main Target 2 - EREC Cutter

to add EREC filament cutter.

the original idea was to add the existing EREC filament cutter Beta7 as is , without any mod, however due to the shape of the erec cutter design, it need  about 10mm + on the left side (the left left outter screw hole), it wastes one more gate, and difficult to reach the endstop. so I have to redesign the EREC cutter for trackrack….also fixed some bugs and make some improvements.

 1 decouple filament cutter from encoder case( as much as possible), I don't like the idea to remake and mod encoder case for every different design change of cutter.  removed the cutter rail on the front face of encoder. 

2 in erec cutter beta7, the cutter knife tip need to be removed. in this mod, no need. knife can be installed as is. 

Modification list

2 existing TrackRack parts -  CarriageLeft,  Carriage Right: added top screw holes to mount encoder adapter.

Carriage Right: modified to support 13mm thick servo.  there are some 13mm servo in the market, they are slightly thicker and more powerful. the output shaft is slightly shorter.

multiple minor improvement on encoder, added countersunk bridge for print quality, reduce friction on bearing and case

using new design for erec cutter, using a new cutter base, make space on the left side.

Install

1 Install Encoder

add heat inserts according to images.

To install Encoder, only replace 2 existing TrackRack parts -  CarriageLeft,  Carriage Right.

And 3 new parts: encoder adapter on carriage, encoder adapter for encoder,  endstop block.

See the blue arraw in the image.See the blue arraw in the image, only 5 small parts to print.

Note the gate switch wire, let it go out from right side from the wire channel.

use M2.6 selftaping screws to mount the endstop block on Carriage_Left.

If not plan to use EREC filament cutter , just to print the ERCFV2 encoder body and install.

It's not provided here so not to make things confusing, as the main target is to manage less parts/less files.

That's it, encoder is added.

due to encoder body is blocking the TradRack selector motor, the existing trackrack gate 0 (the first one), we cannot reach. and that's why we have a longer endstop block.

Use M3X8 screws, refer to all heat inserts position.

use the same M3 16mm on the same tradrack cable cover screw hole to mount the adapter carriage

2 EREC filament cutter

print all erec cutter parts and modded encoder case included.

note, no need to cut the knife tip.

the cutter new design doesn't occupy more space on the left.

servo_gear 

is not modded. same as in erec cutter beta7, included here just for convenience.

Servo Horn_M3:  

Only for 13mm thick servo, they have shorter output shaft, and a M3 shaft mounting hole.

if not using this type of servo, not needed

Using M3X8 for most places.

insert a PTEF (2.5mm id) tube inside encoder behind cutter base body

on the two sides of modded encoder case, the heatinsert is not needed as we don't use the mounting way as in EREC beta7.

Print setting:

stl files are already in correct orientation, can print as is.

no support needed.

3 parameters, infill 20%+

Test

tested,  encoder and cutter works as expected.

Step CAD files provided

Warning:

  binky PCB and BTT mmb pcb (V1) connector pins have different order, double check before connect. if connect in wrong way the binky pcb fries. ( but can be repaired by replacing the 5pin chip, in case you have a few spare : sn74lvc, (which is not really necessary in this ir optocoupler design in my opinion)

update list:

Tip collector bin added.

 use M3 heatinsert on back of the cutter base to mount the part bin holder A

add M6 magnet to bin holder A and B part

use screw to mount bin holder B to bin