Developed as a joint effort by the team from the Qidi Community Discord server. See our Wiki here: https://github.com/qidi-community/Plus4-Wiki

What it does

These models provide for a better chamber thermal sensor mounting location for the Qidi Plus 4.

When mounted as shown, the thermal sensor will track the actual printer chamber temperatures much more accurately than when in the stock position.

Reported chamber temperatures when the chamber heater is off will typically be 10-15C higher than with the sensor mounted in the stock position.

This mod should be used in conjunction with the macro documented here: https://github.com/qidi-community/Plus4-Wiki/tree/main/content/chamber-heater-issue

When used together, this will help to eliminate the chamber heater over temperature issues on the Plus 4 as reported by the Noizieworks YouTube channel, and others, when printing objects taller than 262mm with the chamber heater activated. These fixes will suffice until Qidi supply a hardware fix for the frame of the print bed progressively blocking the outlet of the chamber heater at Z heights above 262mm

How to use/mount

Remove the rear case cover access and cut the cable tie that binds the chamber sensor wire to a much shorter length than when it is fully extended. Use a new cable tie to rebind the remaining wires after freeing the chamber sensor wire from the tied bundle.

Run the now freed thermal sensor up through the hole in the chassis just to the right of the right-hand size XY stepper motor and mount as shown.

This will result in the chamber heater cycling on/off far less often than before, thereby reducing the chance of a thermal shutdown when the print bed is very low in the chamber. Even after the macro turns off the chamber heater at Z heights of greater than 262mm, the user should be able to observe that the chamber temperatures are stable until the print completes.

Use longer M3x16mm machine screws to mount the sensor holder to the chassis by replacing the stock bolts that hold the right-hand size Z-axis lead screw in place. It is helpful to place an M3 washer atop each of the mounting holes in the chassis before positioning the model on top of them, and then inserting the M3x16 bolts through the model, through the washers, and into the Z-axis securing threads.

Use a single M3x8mm machine screw to attach the thermal sensor to the mount model in the orientation shown. Align the metal crimp that holds the sensor as parallel to the edge of the chassis beam as can be managed. It is important that the sensor be aligned with this edge as this results in more accurate temperature readings.

Use another M3x16 machine screw and 3mm hex nut to attach the sensor wire guide to the chassis as pictured to prevent the sensor wire from interfering with the motion system.

Finally, enjoy!