Eigenbau Fiat 180 NT + Bartoletti "volta corretta" semi trailer

[Luca72]

I started this model while I was still building my "Mercedes 1838 4x4". I started drawing the cab just for fun, but when it started to resemble the real truck I decided it had to become my second truck.

At the beginning I planned to make a construction truck with two axle kipper semi-trailer. But I casually saw a picture of a Bartoletti "volta corretta" semitrailer and I decided it had to be "it"

All parts I designed for this model can be downloaded at my GitHub: Fiat180NT and Bartoletti_Trailer

In the next posts I will describe all the steps of the building.

 

[AchimS.]

Looks very nice! What scale is it?

br
Achim

 

[Luca72]

Looks very nice! What scale is it?

Thanks It is 1:14, standard Tamiya scale. To be honest I used 1:13.2 to obtain the correct proportion between cab and tires (I used Tamiya tires).

Luca

 

[Bording]

Hallo Luca,

it´s really impressive what you made!
I am doing alittle 3D printing but honestly I am not good in design. With a cabin I have some challenges. I am using FreeCad.
What design software do you use?

Best regards
Bert

 

[Luca72]

Hallo Luca,
it´s really impressive what you made!
I am doing alittle 3D printing but honestly I am not good in design. With a cabin I have some challenges. I am using FreeCad.
What design software do you use?

Thanks , I use Freecad too. I started with addictions and subtractions of cubes, cylinders and other basic parts. Recently I am using a little bit more Draft to create 2D parts and then I extrude them. I have a lot more to learn, but I am able to design almost all the parts I need.

Fiat 180 cab was a sequence of simple math operations on basic primitives. I am still surprised it came out so similar to the real cab

Luca

 

[drbau]

Hello Luca,
I thought the scale was about 1/50 because it looks much smaller compared to the tiled floor.
But it is a perfekt Model

 

[Luca72]

Cab design and 3Dprinting - Spring 2014



I started just for fun... to see how difficult was to design with FreeCAD a truck cab. But after some time it really started to resemble the real cab.
Fiat "UNI" cab is one of the most beautiful looking cab in my opinion and I could not wait to have it.

Designing took some weeks and at the end the result satisfied me completely.




I never printed such a big object, before, so I tried a half scale print and it came out really nice. So I decided it was time for the real print.
I decided to split the cab in two halves and print it


Here is the lower half while printing






Once both part were finished I glued them together. Then I printed the other parts.


Here is the cab completed:






here is the finished cab compared to the cab of the Mercedes 1838



Once I had the cab ready I had to think about the truck configuration. I always had a sweet point for three axle, twin steering tractors. They were quite popular in Italy in the middle of the seventies. So I decided to use my cab for a 6x2 tractor.

Luca

 

[Luca72]

Trilex rims - Summer 2014



Trilex are the most distinguishable part of trucks from the seventies. They are beautiful and I tried to model them just after I finished the cab.
I have to admit I was particularly successful. So far they were my best designed part. I immediately printed and painted them in red.









Withe the tamiya tires they looked beautiful.

Rear rims were modeled and printed too:




Here another view of the front wheel, complete with the cap:




With all the wheel ready I could have a preview of the truck:



At this point I desperately needed a frame

Luca

 

[Luca72]

Frame - Steering - Summer 2014




When I started designing the frame I had to find a solution for steering 4 wheels. I absolutely wanted to avoid double servo because I do not think it is a reliable solution. Luckily I found the original service manual page of the Fiat 180 steering adjustment. I found only that page of the manual, but it was enough. I copied the mech as it was on the original truck. It consists of two levers that move the axle steering knuckle with short tie rods. And there is a long rod which connects the two levers at different eight. This makes the difference of moving between the front and the rear axle. A big movement of the front lever become a smaller movement in the rear one. Finding the right ratio makes a perfect Ackermann compliant steering with 4 wheels.

I had to design a steering knuckle adapter to be able to use standard Tamiya front axles (they can only actuated using transversal tie rods, I wanted longitudinal attach).






I used really small 3x6x2.5 bearings in the levers to make the movement even smoother:




Here is the mech just mounted:




And here are the double front axles steering:






It worked even better than I though. Using high quality ball joint I obtained virtually zero slash. And the movement ratio was very good: I could use a standard 7Kg servo and it made little effort at steering in any condition.

Luca

 

[Luca72]

Frame - Summer 2014



Trucks from the seventies had leafsprings mounted below the frame instead of having them mounted at the sides. . So frames were wider. I decided for 80mm. I had to create different attaches for the Tamiya leafsprings and for the rear axle I decided to use a partially printed frame. It turned out way more solid than I expected and i never failed in almost a decade. For the rear axle I bought a lockable axle used in the chinese first "Armageddon" truck (it was 8x4 and i had plastic axles). I found it cheap and very similar to the real Fiat axle.
With all the axle mounted I obtained this:



Temporary (waiting for a better solution) the fifth wheel was attached to a crossmember and I fixed the cab. I mounted the axles not at the same height. I kept the central axle slightly lifted. It was not noticeable and the wheels turned anyway, but it gave more traction to the rear wheels.








Now it was time to make it move.

Luca

 

[Bording]

Hallo Luca,

thank you for the detailed report - I will continue to follow

 

[Modellschrauber]

Pretty cool rare project. Well done - Grazie

Dear Luca,

Thanks for this pics, and your detailed report. I remembered this cab.

Kind regards

Christian

 

[Luca72]

Thanks

Thank you very much.