RC Car Stand (TRX4M)

Motivation

My brother wanted to have a stand for his TRX4M RC car manufactured by Traxxas. There are some stands for this platform out there which do the job as well and use very little filament:

• TRX4m Stand & Shock Stand by MDrexAMG or
• Stand for Traxxas Trx4M by Froballer12

But I liked the possibility to spin the car and lock its position as it is done on the original stand sold by Traxxas. But that exact stand is quite pricy. Thus, I wanted to create my own version for a stand with some extra features.

Usage

Rotating the model

This stand uses a similair priciple found in a car's gearbox: Synchronizing rings. However, here we are not trying to synchronize the rotation speed of some shafts. By using an interlocking profile, the rotation of the model can be fixed in 16 different positions.

To rotate the model, you have to press down the locking-ring. If you do so, the upper part of the stand holding the car can rotate freely. If you let go, the ring should snap into the next available position.

Illuminating the model

Here I used some car interior lights to get the job done (Similair to this). 

Side note from the off: I suck at electronics.

I removed the wide plastic stripe at the side and wrapped the remaining strand around the column. The column has a helical notch on it's surface to guide the strand. The notch has a diameter of 2.3 mm and the helix has an inclination of 3 mm per revolution.

Using another stand interface

The top cap can actually be removed from the stand because it's only hold in place by six countersunk hex-screws. The idea was that this stand can also be used for other RC cars by just swapping the caps.

Requirements

This model uses some additional material:

• 20 steel beeds with a diameter of 5 mm
• 12 heat inserts for M3 screws
• 2 Cylinder-head screws (M3x8)
• 2 Cylinder-head screws (M3x30)
• 2 Cylinder-head screws (M3 x16)
• 6 countersunk screws (M3 x 10)
• 3 to 6 springs ( D = 7 mm, H = 10 mm, d = 0.1 - 0.5 mm)
• 3 to 6 springs  ( D = 6  mm, H = 8 mm, d = 0.1 - 0.5 mm)
• Optional: Some lights according to the chapter above
• Optional: Some tools such as files, fine sanding paper, blow torch/ lighter
• Further: A 3D printer, PLA or PETG filament, joy and patience :)

I planned the model using stuff that I already owned. Please let me know if you need something specific.

Printing advice

I printed the models on a Creality Ender S1 Pro using PoyTerra PLA filament (Charcoal Black). The slicer settings in the Cura Slicer were:

• Temperature: 210 °C (Nozzle), 60 °C (Printing Bed)
• Printing Speed: 60- 100 mm/s, except for the first layer (15 - 20 mm/s)
• Layer height: 0.2 mm (or finer if you wish)
• Number of top and bottom layers: 3
• Number of perimeters: 3
• Infill: Lines or Zig-Zag, 20 - 30 %
• Supports: It depends (See the Gifs below)

Assembly

I recommend assembling the top part first:

1. Place the “Bearing Spring Cap” upside-down on a flat surface.
2. Insert the springs (6 x 8) into the blind holes.
3. Pin on the “Bearing Cap”  onto the  “Bearing Spring Cap” and make sure that the holes align.
4. Insert 10 beads into a bead cage and place it onto the corresponding bearing track. The tip of the cage should be facing downwards.
5. Place the “Stand Carrier” upside-down onto the steel beads.
6.  Again, insert 10 beads into a bead cage and place it onto the corresponding bearing track. The tip of the cage should be facing downwards.
7. Place the “Locking Plate” onto the steel beads facing upside down and screw it to the  “Bearing Spring Cap”

After that, you can start assembling the column part:

1. If you have some kind of lights as mentioned before, wind the strand along the helix of the “Column”.
2. Screw the “Column Base” to the “Column” and make sure that the strand for illuminating the column passes through one slot on either side of the coulumn. This slot should also align with the slot of the base plate.
3. Insert the “Struts” into the holes of the “Column Base”. They should have a loose fit. You can glue the into place after final assembly if you wish to.
4. Pass the strand through the slot at the top of the “Column”. Then press down the “Column Cap” onto the “Column” and make sure that the holes align. The tricky part is inserting the “Struts” into the upper holes as well.
5. Place the springs “7x10” into the holes.
6. Place the “Locking Ring” onto the springs with the holes aligned properly.
7. Then, insert the assembled top part into the “Locking Ring” and screw it onto the bottom part. This part is probably the trickiest. Good luck with that!

With the top and bottom part connected, you can finally screw the “Stand Cap” to the “Stand Carrier” using six screws.

Top View:

Section A-A:

Section B-B:

Future Plans

• Improving assembly experience
• Move the bearing and the locking mechanism to the bottom of the column
• Using less variation of standardized parts (e.g. one screw size and length, one type of spring)
• Use different strategy on illuminating the model