Rack and pinion steering

One of my first experiments with 3D printing was a steering rack, pinion and housing for a little project I’m working on. It came out very nicely, in terms of both finish and fit. 

Top view. The ID of the bearing is 12mm. 

Front view, with bolt holes through the housing clearly visible. The rack and pinion are module 3, which seemed about the right size. 

I left spaces into which ball bearings were pressed, one above the pinion on the outside of the housing and one under the pinion inside the housing. 

The key way in the pinion is just visible through the bearing in the photo below. 


And with a 12mm OD stainless tube turned lightly to fit:


I did a couple of experimental universal joints, printing the whole assembly as one, to work out the optimum gap between moving parts:

Before deciding that I actually wanted two universal joints, with an extending section between. A little more time on the CAD and here is the result installed:

The bracket being held in place by a clamp contains two sets of bearings and will be bolted to the stainless box section. This was my first bit of aluminium welding for real. 

A quick test of the steering revealed that the universal joints were not strong enough; I am now working on a new solution.