This document covers prerequisites for your printer to work with Trad Rack, as well as other hardware you might need/want to use with Trad Rack.
Table of Contents
Your 3D printer must meet the following requirements to work with Trad Rack:
- Must use 1.75mm filament.
- Must run Klipper firmware.1
- The toolhead or extruder must have a collet/coupling to secure a 4mm bowden tube at the inlet.2
Trad Rack requires the following ports for its actuators and sensors:
| Port | Quantity |
|---|---|
| Stepper motor output port | 2 |
| Endstop input port (pins: GND, signal) | 2 |
| Servo output port (pins: GND, 5V, PWM) | 1 |
If your printer's main control board already has these ports/pins available, you can connect Trad Rack's actuators and sensors directly to the board. If you do not have these ports available, you may need to use a separate control board for Trad Rack. The option of using a separate control board attached to Trad Rack also allows you to easily connect/disconnect Trad Rack from the rest of your printer with only USB and power cables.
In addition to the ports listed above, you will need a port for a toolhead filament sensor.3 This will likely be a simple endstop input port, but it may depend on the type of sensor you use. It is recommended to use a port either on your printer's main control board or on a toolhead board (rather than on a separate control board attached to Trad Rack) as doing so will likely simplify the wiring.
If you choose to use a separate control board attached to Trad Rack, see the table below for some example recommended control board mounts4:
| Board | Name/link | Comments |
|---|---|---|
| Annex Nebula | (provided enclosure) | |
| BTT SKR Pico | Skr Pico mount for Annex tradrack | |
| BTT SKR Pico | Ender 3 SKR Pico Mount (for Voron Switchwire Conversion) | |
| Fysetc R4 | Fysetc R4 board case mount | |
| EASY BRD | ERCF EasyBrd/CAN Brd mount for TR |
Using a filament sensor on your printer's toolhead is highly recommended.3 This sensor can have its trigger point be above the extruder gears, below the extruder gears, or at the extruder gears (e.g. by sensing the idler arm movement). See the table below for some example recommended sensors4:
| Designed for (printer/toolhead/extruder) | Name/link | Trigger location | Comments |
|---|---|---|---|
| All | Inline Filament Sensor | Above extruder gears | Meant as a universal fallback option if you can't find a sensor designed for your setup. Requires that the toolhead/extruder has a bowden coupling/collet. |
| Sherpa Mini | Sherpa Mini Idler Filament Sensor and Collet | At extruder gears | |
| Sherpa Mini | Sherpa Mini extruder filament sensor and Collet Mod | Above extruder gears | |
| Sherpa Micro | Sherpa Micro Idler Filament Sensor and Collet | At extruder gears | |
| Sherpa Micro | Sherpa Micro extruder filament sensor and Collet Mod | Above extruder gears | |
| Clockwork 2 (Voron Stealthburner) | CW2 with sensor, magnet, and ECAS | Below extruder gears | |
| EVA 3 | EVA 3 Toolhead Filament Sensor (Mechanical and Reliable) | Below extruder gears | |
| E34M1 | E34M1 Toolhead Filament Sensor | Below extruder gears |
Trad Rack requires a buffer for each filament.5 The buffer provides a place for filament to collect when it is retracted from the toolhead back into Trad Rack, while ensuring that the filament does not get tangled when it needs to be used again.
The following are some items you may want to take into consideration when selecting a buffer design:
- Filament capacity: each buffer must be able to fit a length of filament approximately equal to the length of the bowden tube between Trad Rack and the printer's toolhead/extruder.
- Number of filament loops: some buffer designs wrap the filament around a wheel. The filament can be looped around the wheel for part of a revolution, a full revolution, or multiple revolutions. In general, a buffer with more loops takes up less space for the same filament capacity, while a buffer with less loops does not add as much resistance to filament movement. If you have the space for it, a buffer with 1 or less loops is preferred.
- Snag points and filament constraint: some buffer designs with wheels may have the possibility for filament to slip around the wheel and get stuck. It is important to keep the filament well-constrained and prevent snagging. In addition, it is important to ensure the filament does not cross over itself in ways that may cause a tangle.
- Induced filament movement: it is important that the buffer does not push or pull the filament while it is buffered, as this may block the movement of Trad Rack's selector or prevent Trad Rack from being able to grab the filament. Long narrow buffers (in which the filament follows one wall, makes a U-turn, and follows an opposite parallel wall back) are particularly good at avoiding this problem, since the only forces exerted by the walls of the buffer on the filament are perpendicular to the filament. If you are having problems with the buffer causing the filament to move, you can try adding a section of PTFE tube with a 2mm inner diameter at the inlet to Trad Rack's filament modules to add more resistance. See the Extruder Syncing document for ways to compensate for the added resistance by using Trad Rack as a secondary extruder.
- Bend radius: different filament types may require a different minimum bend radius in order to avoid breaking the filament or causing excess resistance in the filament path. For example, filled filaments may require a larger minimum bend radius than non-filled filaments. It is important to select a buffer that satisfies the largest minimum bend radius of the filaments you might use.
- Mounting: some buffer designs are meant to be attached to the printer. Others fit inside a filament drybox so that the filament inside the buffer is kept dry. You may want to consider how the buffer will fit into your printer and filament management setup when selecting a buffer design.
See the table below for some example recommended buffers4:
| Filament capacity | Name/link | Comments |
|---|---|---|
| 3 sizes: 640mm, 1068mm, or 1294mm | Stern-Wheeler | |
| 900mm | MMU Filament Buffer ~900mm | |
| 550mm | Bigger 6 Bay Slot Buffer | |
| depends on acrylic/cardboard length | Simple Slot Buffer | |
| 300-1800mm (see table in readme) | piKa |
Trad Rack can be mounted however you want: to your printer, to a filament storage enclosure, to a table, etc. For most setups, it will likely be most convenient to mount Trad Rack directly to your printer.
We provide mounting brackets for attaching Trad Rack to the side of an Annex K3 printer; these brackets can be found in the Trad Rack Mounts folder.
The following community-designed mounts are also recommended4:
| Designed for | Name/link | Comments |
|---|---|---|
| Voron Trident/V2.4 | Offset 2020 mount for Voron's | Requires an extra-long extrusion |
| Voron Trident/V2.4 | BYOLE teookie's Offset 2020 mount for Vorons | Requires an extra-long extrusion |
| Voron Trident/V2.4 | Tradrack "beta" 45 angle mount voron | Requires K3 side mount brackets as well. May require an extra-long extrusion. |
The recommended way to mount Trad Rack is to attach brackets to the underside of its 2020 extrusion, and then attach those brackets to whatever you are mounting Trad Rack to. Depending on your setup, you may also want to consider using an extra-long extrusion for Trad Rack so that you can use more sides of the extrusion to attach brackets at the ends.
It is recommended that the underside of Trad Rack's extrusion is spaced at least 11.6mm from any surface below it in order to maintain compatibility with any electronics mounts that are attached to the underside of the extrusion.
The following are optional items that can be added to your printer for use with Trad Rack.
See the Extruder Syncing document.
An alternative to PrusaSlicer's tip-shaping process for getting clean filament tips at the beginning of an unload is to use a filament cutter. A filament cutter cuts off the end of the filament, which may be bulged or stringy, in order to leave a clean end.
Trad Rack currently supports using a filament cutter mounted to the printer's toolhead (see the Customization document for more details on software setup). Support for a filament cutter either inline with the bowden tube between Trad Rack and the toolhead or mounted to Trad Rack's selector is planned but not implemented yet.
The most common method for purging material at the end of a toolchange with Trad Rack is to use PrusaSlicer's wipe tower. However, you may want to consider using a purge bucket with a nozzle wiper for a portion of the purging6 to reduce the size of the wipe tower and reclaim build space.
In addition, a nozzle wiper and purge bucket may be useful if you are replacing PrusaSlicer's ramming procedure (which deposits material on the wipe tower) with your own tip-shaping procedure that produces waste material that must be collected. See the Customization document for more details on tip-shaping options.
For the Annex K3 printer, the
trad_rack_optional.cfg config file
provides the option of performing the tip-shaping process over its
purge bucket and wiping the nozzle afterwards. This option can work
with other printers as well (with their own bucket/wiper setup) if
Go_To_Purge_Location and Wipe_Nozzle macros are included, either
by copying these from a provided
K3 config file
or by writing your own implementation of these macros (or by
modifying/replacing trad_rack_optional.cfg). If using this option on
another printer, it is recommended that you pick a bucket/wiper that
stays at a constant height relative to the toolhead so that you do not
risk the toolhead crashing into the print when it moves to the bucket.
Footnotes
-
We only provide software for using Trad Rack with Klipper. However, Trad Rack's hardware is not inherently reliant on Klipper, so you can use it with another 3D printer firmware if you write your own software for making Trad Rack work with that firmware. ↩
-
If you are adding a mod to your toolhead in order to add a filament sensor, it is likely that the mod also includes support for a bowden collet/coupling. See the table in the toolhead filament sensor section for example recommended sensors. ↩
-
A toolhead filament sensor is highly recommended for reliability and precise filament positioning, but it is not quite mandatory. ↩ ↩2
-
If there are other control board mounts, toolhead filament sensors, buffers, or Trad Rack mounts that you think should be added to the tables in this document, feel free to submit pull requests to add them. Please only submit a pull request once you have tested the design with Trad Rack and confirmed that it works well for you. ↩ ↩2 ↩3 ↩4
-
It is also possible to use an "air buffer": a short section of bowden tube is attached to the spool holder and another to Trad Rack's lane module, and a gap is allowed to form between the 2 tubes for the filament to expand. This setup is not recommended as a permanent solution since it is very messy and the filaments may tangle with each other. However, if the filaments are separated from each other so that they cannot tangle, this setup can be very reliable. ↩
-
To completely eliminate the wipe tower, additional code would be required to tell Klipper how much material to purge depending on the specific filaments being unloaded and loaded. However, it is recommended to always at least use a small wipe tower to ensure the hotend is primed for printing (as is commonly done on toolchanger and IDEX setups). ↩