DRX042 TPU wrap gearknob for Thrustmaster TH8S

The DRX042 gear knob for the TH8S came about after wondering if the look and smooth layer line free feel and look of a Carbon Fibre textured build plate could be transferred to a cylindrical shift knob. After great results printing a thin flexible test layer of TPU95a on the plate I devised a way to wrap and lock it around a shift knob body. The shift knob is also modular to give many options for customising colours.
The gearknob a little under 42mm diameter, and assembled with all bolts weighs a bit over 60 grams.

Please note, there are some specific (but minor) bolt/tool requirements to build this knob, these design choices are kind of forced due to the combination of the wrap mechanism, modularity and size of the design piece affecting internal spacing.


Requirements:
-Carbon Fibre textured build plate (relatively easy/cheap to source - kind of necessity as shiny/grained texture plates don't look anywhere near as good)
-TPU, 95A preffered (for wrap pieces and spacer rings)
-6pcs M3 6mm Countersunk Hex key bolts
-3pcs M3 16m or 20mm Countersunk Hex key bolts
-Hex driver with relatively long shaft (around 50mm, and should be a 2.0mm hex driver)

I used PLA+ for most pieces, and played around with metallic/Silk PLA. You will have to be careful not to overtighten bolts with Silk PLA, as good as it looks in silver. I think Silk PLA will hold up to long term use, but the PLA+ definitely feels more durable and like it would survive more taking apart and putting back together.


Printing tips:
-No supports needed!
-Print all pieces in the orientation they are imported in, do not flip/rotate (if uncertain look below in this page at how the're oriented in the model STL thumbnails!)
-To print the thin "Keystone Strip Cover" piece in it's vertical orientation, do not use a brim (it will be a pain to clean the part up), but you should CLEAN YOUR BUILD PLATE PROPERLY.
-Carbon fibre texture plate also works great for the top badge - I used PLA for those.
-If using a TPU colour other than Black for the wrap pieces, they can sometimes be semi translucent, for lighter colours (like white/red shown) you will want to print the main body/keystone strip cover in a similar colour PLA.
-Print Threaded Collar and Top Piece each by themselves on a smooth/non grained plate (CF texture plate will be fine) as grained PEI will leave more of a gap when screwed together. Also do better than me at orienting the seams in a less conspicuous place!
-To print the Thrustmaster Top Badge you will require a printer with a filament colour changing system, the Blank Top Badge is there if you just want plain CF look texture or if you were to import the model and design your own (I attempted a H pattern design but it didn't look good on this style of knob)

Printing and Assembly:

1)Using TPU95a, Print TPU wrap cover for Main Body,  TPU wrap cover for strip and Default TPU Spacer Alignment Ring on the same Carbon Fibre Texture (or similar) plate. Align the two Wrap covers next to each other on the bed so they will share a similar pattern.

2)For the remaining pieces, print in your materials of choice. Taking note of above printing tips for colour choices when using lighter colour TPU. Black for the most part is the best choice.

3)Print one of the top badges, Thrustmaster Top Badge if you have a colour change printer, or use the blank the CF textured build plate if not.

4)Carefully align and wrap the Main TPU Wrap piece around the Main Body piece, as shown in pic. Push the TPU into the crevices, then when it's mostly wrapped around entirely fold it over the upper edges of the main body, pressing the TPU into the ridges (don't know how else to explain this, please look at photos carefully!)

5)Screw the Keystone Piece in with 3 x 6mm M3 countersunk bolts, you can probably get away with 8mm bolts for the upper two bolts if that's all you have, but the bottom M3 Bolt has to be 6mm (leave it off if you only have 8mm on hand or the strip cover won't sit properly!)

6)Attach the Threaded Collar to Main Body assembly using the 3 x M3 16mm bolts (can use 20mm, possibly 25mm too).. Due to the design requiring long holes for the concealed bolts, your hex driver may slip off the bolt head and be difficult to realign on the bolt. You can print my hex driver helper piece (suits 3mm round diameter hex driver shaft) which makes it ever so slightly easier to get back on the bolt head.

7)Attach the TPU wrap cover for strip to the Keystone strip cover.. Moderately difficult, but not impossible, just requires sa little patience and folding/pushing in the right places (see pics!)

8)Slide the assembled strip cover onto the main body (see pic)

9)Attach the Top piece with 3 x M3 6MM bolts (8mm, 10mm should also work here)

10)Place the top badge on, it should have just enough tolerance that it wont fall off when turned upside down. If it is loose (like my silver one was, due to different material properties of Silk PLA), use some some masking tape/painters tape or similar to stick around the sides of the badge until it is a tighter fit.

11)Place the default TPU spacer ring into the threaded collar (see pic, ie. the red TPU ring)

12)I've made a small visual notch in the competition provided "Design Piece"/adapter to help give a visual clue to which direction the knob/adapter should be facing. Screw the knob onto the piece and when it is tightened moderately that the notch faces the same direction as the logo/strip. The gear knob orientation in relation to the design piece may work for you first with the defult 0.55mm spacer without needing adjustment but I found things can vary from printer to printer/filament to filament.. if the default spacer isn't right then....

13)Print out some spacers from the spacer collection until you find a spacer that aligns well. An educated guess is the 0.4mm to 0.8mm range would suit most cases, unless wanting to run the knob with the strip side facing towards you or some other edge case. For reference a 0.4mm spacer is actually 2.4mm in thickness, with the 2mm sitting inside the threaded collar with the protruding 0.4mm acting as the spacer.

There are two sets of spacers in the folders below, one with ID labels on them, the other without and also a flange on them to fill the gap between the knob and adapter better. You can just cut the labels off the labelled ones if it's easier for you though.

Tinkercad link for the spacers if you need to dial them in to an even finer degree (eg 0.05mm steps):
https://www.tinkercad.com/things/iNBgLQFDzBb-sharelink-drx042-thrustmaster-th8s-spacers?sharecode=d0RTyaqk-p-iSHX8SoGVjqHUYEj79SdpyP5CxhkRPzc


Update..  Full Tinkercad Project link:
https://www.tinkercad.com/things/lG3fORHXHv6-shared-thrustmaster-th8s-tpu-wrap-gearknob-final?sharecode=XZah3iDTfMJ0vVXbqD_U2OqH8v28awy-Ka8d_rt97ik


Anyway, hope the wall of text isn't too offputting or TLDR, for the most part it's going to be best to follow your intuition and the assembly pictures!