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Building a Custom RC Hotrod, Design and Fabrication

In the last post we looked at the inspiration for this build, in this post we look at turning it into reality. 
Before starting the complex CAD work, it is always wise to get an idea of the final size, so I scoured the internet for reference material (it helps here to choose a popular model, like the '32 ford) and printed out a profile, scaled to exactly 1:10, and laid parts out on it. 
The next step was sourcing the parts that I could not build myself, I needed to know their sizes so that I could design around them

Rear axle and gearbox from an SCX10 rock crawler
Front axle from a 1:14 Tamiya Semi truck 
Drive shaft from a Axial Yeti (for length, since the motor is in the front)
7.5 Turn Brushless motor and 120A ESC since an inappropriate amount of power is appropriate in a hot rod.

All of the CAD work was done on Autodesk's Fusion 360, a parametric modelling tool which is free to hobbyists and start-ups, and well worth learning if you are interested in tackling your own designs.



Once the design for the body was completed the files were uploaded to Shapeways, a 3D printing service based in the Netherlands. Shapeways employs the laser-sintered nylon method, which lays down fine layers of nylon powder and selectively fuses them with a laser, resulting an incredibly tough, slightly flexible, end product. 



The chassis of the car was designed to be laser cut and bent from 3mm and 6mm aluminium, a process that is surprisingly affordable, and can easily be done locally (I used Vulcan Steel in Milnerton). It is worth remembering that the laser cutting process can't handle holes of a smaller diameter than the thickness of the material, so the various 3mm holes in the 6mm plate had to be drilled and tapped by hand. 

 

Once all chassis and body parts were on hand the assembly went quickly. Custom length links for the four-link suspension were fabricated from aluminium ball-ends and threaded rod, sheathed in plastic irrigation tubes.



That about does it for the design and fabrication, tune in next time for painting and finishing!