Another RC hobby? I'm already into RC scale model boats (since the early 1970's) and RC armor (since 2015) I am branching out to RC scale vehicles (but not too many). Notice the word scale in each of these three segments of RC hobbies.

This topic is for a RC semi tractor and lowboy trailer being converted from an inexpensive toy. It is already in 1/16 scale and should be compatible with my Springer ("truckable") tugs and Armor (tanks, etc.). I plan to use it at both Model Boat and Armor meets.

This first segment involves the selections I have made and my plan to make the necessary modifications to the toy.

I bought two ERTL about three years ago with the intent to convert them into RC. I paid about $70 (US) for the pair of them on sale. They are currently in the $70-80 range (each). They look good enough to use although not to exact scale. The project goal is to keep the cost down and have a fun functional vehicle.

Why buy two units? When done, I will be using parts from the second vehicle for the first, like wheels for extra axles and other parts.

Right now I am working on the semi-tractor. The new unit will have another axle, this one to lift by RC. It will also have the extra sleeper cabin and other accessories. I am planning to make the "gooseneck" (the part that connects to the trailer) RC controlled. Unfortunately the model's lowboy trailer suffers problems like the real trailers do. Too close to the ground. I will need to elevate the trailer sufficiently so it will not get stuck. I do not have to contend with railroad tracks which makes the vehicles good targets for fast moving trains.

The latest:
This evening I am cementing the chassis frame together. I had to print it in five pieces due to the limitations of my 3D printer. There will be rectangular steel tubing epoxied inside the frame for extra strength.

Lew

HO scale? That's on the horizon for me as well. What I have is old, control by transformers via the tracks. Then it went to DCC where the tracks had constant DC and control by radio signal. I was thinking that a better setup would be total RC, no power to the tracks. Batteries are small and powerful. Any thoughts?
Lew

As I had decided to lengthen the chassis/frame by almost 8 inches (200mm), I decided to make a new frame (as previously shown). The new frame incorporated the mounting of items from the original truck now includes the mounting of the new items (servo mounts, motor and transfer case, axles, sleep cabin, etc.

The layout was done in my 3D CAD app (see photo). This also includes a suspension system as the toy truck had nothing but oblong holes to simulate up-down movement of the wheels.

Current Status:
The frame was printed in five pieces due to the limitations of my 3D printer's build plate. The cross-section is "U" shaped as I had some square soft steel tubing that would fit inside the "U". That was placed inside using JB-Kwick epoxy. Clean-up is currently in progress.

Lew

Going to take a look at the power train parts I am accumulating for this project. (Trying to use what I have rather than buy new items.) So here is what I am looking at:

Geared Motor: Zheng ZYDT520, 550 RPM @ 12VDC.
Transfer Case: My 3D build + bearings 1:1
Axle #1 (front): Steerable (source unknown) 1/16 scale
Axle #2 (retractable): My 3D build
Axle #3 (through-put): (source unknown) 1/16 scale
Axle # 4 (end): (source unknown) 1/16 scale
Suspension Front: My 3D build, leaf spring
Suspensions Rear mains: My 3D build Coiled springs
Support plates and brackets: My 3D build
Servos: Futaba S3005 (2)

Having build the transfer case and gears with a 1:1 ratio, I can change the speed OR tractive power of the vehicle simply by making a new transfer case. This case takes the output from the motor and has two output shafts, one to the front and the other to the rear.

My concern right now is if six channels are enough?

Now back to 3D printing.

Lew

Still working on this truck chassis. Making changes to the suspension as I go. Big issue is how much weight can it handle and how should the ABS suspension parts be designed. I think the last of several itineration's will work. Want the axles (all spring loaded) to move up and down.

New sound an lighting system arrived. Getting anxious to see this thing run.

Lew