Kingsong S18 side panel and fairing replacement

Overview

This is a complete 3D printed replacement for the Kingsong S18 side panels. The aim is to create a more ergonomic and slim design that enables the use of any pad setup while adding more protection and making it much easier to work on the wheel.

Modular design

This is a modular design meaning each side panel is composed of multiple pieces. These pieces are then screwed into one another using heat inserts. Designing the system this way makes it easier to print on smaller print beds, and if a part gets damaged you only need to reprint the damaged panels–not the entire thing.

I also have created attachment points on the front and back of each panel that allow accessories or other attachments to be screwed into the panels. Included are front and back bumpers that can be printed (in TPU preferably). The front bumpers also act as a stable stand for the wheel.

Printing instructions

There are a total of seven pieces that need to be printed on each side. I recommend printing these in ABS, ASA, or PETGfor the better thermal properties and higher impact resistance. I needed to use a brim as these pieces are large and flat. The included model pieces are for the right side of the wheel. Mirror everything to print the corresponding left side panel.

Note: This design makes extensive use of heat inserts. I’ve added a bit of pre-compensation for shrinkage for these inserts, but you may need to do some smaller test prints to dial in these settings. I also recommend adding more wall layers around the heat inserts to give them more strength. How to do this will be slicer dependent.

Suggested print order

Front Screw Holder.stl: This piece provides backing to screw the front panel pieces into. It is the quickest piece to print and will let you test out your heat inserts. The heat inserts are M3 with a 4mm height. Suggested infill: 60%.

1) Bracket.stl: This is the central backing piece that all of the other panel pieces attach to. There are indentations that give additional clearance to the sliders. The indentations should be placed facing the sliders. This pieces uses the most heat inserts of all parts. Like the previous piece, they are all M3 with a 4mm height. Using longer inserts will potentially interfere with the sliders. Suggested infill: 60%.

2) Front Top.stl and Front Bottom.stl: The two front pieces. These both screw into the bracket printed in step 2. There is also a single M3 with 4mm height heat insert that is placed into the front bottom piece that allows the front top to be screwed directly into it. Both of these pieces contain additional M4 heat insert holes on the front to attach accessories. The front top piece has an additional M4 heat inert hole at the top right on the flat side. Suggested infill: 20-40%.

3) Back Top.stl and Back Bottom.stl: The two back pieces. These also screw into the bracket printed in step 2. On both pieces there is a single M3 with 4mm height heat insert. This allows the back top piece to screw into the back bottom piece, and the front top piece to screw into the back top piece. Again, there are additional holes on the back of these pieces for M4 heat inserts to hold accessories. Suggested infill: 20-40%.

4) Cable Cover.stl: This pieces screws into the bracket using 6 screws. By removing the six screws you can access the sliders in case you need to lubricate them. It also allows you to access the motor cables directly. It should be possible to drop the motor without needing to remove the the entire side panel. This makes maintenance issues and tire changes much quicker.

5) Optional Front and Back bumpers: These provide extra impact resistances. The front bumpers also act as a stand. These attach to the case using M4 screws/hex bolts. Print in TPU with an infill of 15-20%.

I have also included a merge file that merges all of the panels except the front screw holder and the cable cover together. If you have a large print bed, then you might prefer printing this model in a single go. I have not tried this as my printer is smaller.

Assembly

After printing out the pieces, you need to put in the heat inserts. This takes a bit of time, but makes future work on the wheel much easier. Each of the pieces by themselves may feel flexible, but once we screw everything together we will have a sturdy case that should be a significant upgrade over the stock case.

The two heat inserts I use are:

M3 4mm long: https://www.amazon.com/gp/product/B0B398W1CC

M4: https://www.amazon.com/gp/product/B09ZNX3ZCS

I also use 6mm long M3 hex screws like to attach the case pieces together: https://www.amazon.com/gp/product/B00W8YSCIS.

Once the pieces are fitted together, attach them to the case using M3 screws or hex bolts. The ones that come with the case should be fine to use. The back of the case attaches to the rear battery box with three M3 screws. The front of the case is attached by first placing the front screw holder (part 1) so it lines up with the holes on the front battery case. This piece goes between the wheel and the battery. Now the front case can be screwed into this backing. There are two additional screws that attach the top of the case to the wheel.

Notes:

The design still isn’t perfect. Modeling the top rear portion of the S18 is difficult, and the rear top piece is a few mm off in a few places in the very back. I may get around to fixing this one day, but for my purposes this works quite well. The S18 sliders gain significant additional protection against debris as they are no longer open to the elements. The case also does not interfere with the operation of the sliders. After 400 miles of riding in the snow everything has held up very well.