Qidi Plus4 Super-light Rear Toolhead Cover

Strong, super-light, minimalist rear tool-head cover for the Qidi Plus 4

Important: Read the Caveats section below even if you read nothing else!

Updates

3rd April 2025: I've uploaded a slightly wider model.  There was a chance in a very particular scenario, that the original mount could catch a misaligned purge activation lever in a very particular printer movement when executing the stock Qidi filament unload operation.  The new wider model should eliminate this unless your purge activation lever is severely misaligned.  Also added the superlight-nitro-edition for you know who. ;)

8th July 2025:  I've uploaded a new variant that minimises the size of the skirt of the “Nitro” version, as well as adding in a mount point for a 25x10mm fan.  The purpose of this fan mount is to allow for better cooling of the tool-head and stepper motor in heated chamber scenarios.
 

Introduction

The stock rear tool-head cover for the Qidi Plus4 is a 2-part item, and is moderately bulky in both size and weight, coming in at approx 29g (a little over 1oz).  The stock rear tool-head cover also does double duty by providing a flat and strong surface to push on the filament purge bucket activation lever at the rear of the printer.

This replacement super-light cover utilises organic curves to provide for a surprisingly strong but minimalist piece that still protects the rear tool-head electronics, and is still able to activate the purge bucket lever extremely well when it is secured against the tool-head by using the same 4 screws that secured the old tool head in place.

When printed in PA6-GF25 this pieces comes in at 8.0g when sliced using the printing recommendations below.

The weight reduction of 21g over the stock cover will provide for better input shaper performance.  It is strongly recommended to re-run input shaper calibration after installing this cover.

Printing Recommendations

• 0.2mm layer height
• 0.4mm nozzle
• 3 walls
• 5 bottom and 6 top layers
• 0% infill
• Height Range Modifier 0-1mm of 100% infill
• Height Range Modifier 23-26mm of 4 walls

Recommended Filaments

A high Temperature Filament such as ABS, ASA, PC, PA, PET.  CF or GF filled filaments will provided for greater strength when pushing against the filament purge arm.

Installation

Turn printer off and slide up the stock rear cover sliding piece, and remove the 4 screws holding the rear cover shell in place.  You may need to move the print head towards the front of the printer and rotate the drag chain in order to free the stock cover shell.

Using the 4 screws removed from the stock rear cover, insert the screws in the screw wells of the replacement cover, and attach the replacement cover to the print head using the same screw holes used by the stock cover.

Once installation is complete, power the printer on and re-run the input shaper calibration.

Caveats

When installed on a Plus 4 in place of the original rear cover, AND if no front cover is installed, the the X-axis will gain an additional 1.5mm of end-stop travel.  This must be accounted for in the printer.cfg file by modifying the following fields in the [stepper_x] section:

[stepper_x]
position_min: -3             # Original value -1.5
position_endstop: -3         # Original value -1.5

Doing so will prevent the left side of the print head from bumping into the Z-Axis supportive brackets during PRINT_START and Homing.  Again, this is ONLY necessary if the front cover has been removed, AND this rear cover is being used.

Additional note, if you are using my Beacon mount model, you do NOT need to perform the above adjustment as my Beacon mount provides the same X endstop coverage as the stock front cover.

Support
 

Enjoying my work?  Consider buying me a coffee!    https://ko-fi.com/stew675

Weight optimised remix of my original design.