Modular Exhaust System for the Qidi Plus 4

A modular exhaust system for the Qidi Plus 4

These models are designed to completely overhaul the stock exhaust system on the Qidi Plus 4, which has a number of significant inadequacies, not the least of which being that it simply doesn't work nor do anything of value.  Provide are a set of pieces to assist with drilling the exhaust point mounting holes, replace the poorly designed filter cage, prevent hot air from entering the mainboard electronics chamber, provide a solid and secure mounting mechanism to attach an exhaust duct onto, and then provides for a set of pieces to direct the outlet air and attach either a 3" or 4" flexible hose to for routing the exhaust air.

Why?  What's wrong with the stock system?

Firstly, let's take a look behind the existing filter bag holder piece.

Here we can see two large rectangular holes that lead directly into the mainboard electronics chamber.

Further, when the stock bag cage is installed, it does nothing to block off these holes.  Additionally, the activated carbon filter bag is extremely restrictive.  The fairly weak 80mm exhaust (chamber circulation) fan can pull almost no air through the stock filter bag  On top of this, axial fans do not perform well when working against a restriction at the intake side.  They are much better at providing pressure against a restriction. 

I put a thermal probe inside the chamber near the filter bag cage, and another thermal probe after the exhaust outlet and found that the exhaust air that came out was barely above room temperature.  It seems that the filter bag was completely blocking off the fan from pulling hot air from the chamber, and instead all it was doing was pulling in air from the mainboard chamber and exhausting out the back.  The filter bag was doing almost nothing, and the fan was not providing any cooling effect if the chamber was getting too warm.

Additionally, the inside the exhaust duct after the fan just rests against the inside of the rear case panel.  There is nothing prevent airflow from leaking past the edges and directly into the mainboard chamber.  This would act to increase the temperature inside the mainboard chamber if the filter bag is removed.

The Plus 4 also offers no pre-drilled holes from which to attach any ducting to the printer.

Therefore, number of things need to happen here:

1. Remove the filter bag from this location, and provide as little restriction as possible into the fan inlet
2. Block off the intake holes leading to the electronics chamber
3. Seal off the outlet of the internal duct from the main-board chamber
4. Provide a way to accurately drill mounting holes for an externally attached ducting system
5. Provide a mechanically strong and secure mounting mechanism to attach an external duct system to

My Solution

A very low restriction, slide into place, replacement for the stock filter cage.  Do not re-use the stock filter bag with this piece.

The duct cage is placed into the main chamber like so.

A duct insert sleeve, into which M4 square nuts may be inserted, bolted onto the rear panel, and slid into the existing duct to seal off the duct exhaust from the main-board chamber, and route air-flow more smoothly into the existing outlet holes

A drill stencil, designed to be printed out of your cheapest filament, that will securely seat itself at the correct orientation on the stock exhaust vent holes, and allow you to use a 4mm, or 5/32", drill bit to accurately drill mounting holes into the rear panel

A quick demonstration for drilling out mounting holes in the rear panel

After drilling, the rear panel should now have 4 accurately placed holes like so:

 

Using 4 of M4x16mm machine screws, affix the rear duct elbow and the internal duct sleeve to the rear panel:

 

The rear 45 elbow can be attached in any of 4 orientations

Additional Elbow pieces and hose adaptors may be slid onto the end of the exhaust pieces.  They will snap-lock into place with friction, and may be removed later by pulling the pieces apart firmly.  Shown here is an additional 45 degree elbow, and a 3" hose adaptor end piece for attaching a flexible exhaust hose onto.

The elbow pieces may be clicked into place in any of 8 orientations to allow for flexible routing options.

Printing Tips

All pieces are easily printed using a 0.4mm nozzle with a 0.2mm layer height.  No supports are needed, although some slicers may complain about unsupported areas, this won't be an issue.

Do not use PLA.  As the exhaust temperatures of the Plus 4 are capable of touching on 80C, it is recommended to use PET, ASA, ABS, PA, PPA, or PC.  Using fiber composite filament is of benefit as it provides for better dimensional accuracy and allows for the parts to click together better.

The fan grill cover is designed to be printed in the following orientation without supports:

 

The duct sleeve is designed to be printed in the following orientation.  No supports are needed.  The part is designed to use bridging where necessary

All other parts are designed to be printed with the female end facing the build plate.

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