There's a full video of the steeing build here and at the bottom of this article.

With the forks in place and looking pretty good I needed to create a column and handlebar assembly.

The first thing I did was trim the excess height of the threaded section of the steerer tube.

The plan is to use a universal join to extend a rod back to the seating position and connect some pretty long handlebars to this to give me plenty of leverage to thrun the wheel.

The steerer tube is 20mm so I found a reasonably priced UJ and cut a length of 20mm pipe on the bandsaw.

I attached to UJ to the steerer tube and the pipe using M8 bolts. I tapped the steerer tube and the pipe to keep everything tight.

The handlebar clamp diameter was larger than the 20mm of the steering column pipe, so I created an adapter from aluminium scrap piece.

First thing to do was turn it down to fit the handlebars

And then bore it to 20mm for the steering column

I then split the adapter with a slitting saw to allow it to clamp onto the column.

Then it was fitted onto the column

And the handlebars fitted.

A quick test showed that this layout worked well. 

The column needs to be supported. The achieve this I designed  support arm that can be folded flat and height adjusted as required. Steel adjustment plates attached to the frame provide a pivot point and a circular slot allows for angle adjustment and clamping.

The steering column is attached to these arms with a pillow block bearing mounted on the device at the end of the support arm. This allows for the rotation of the column and the column slides through the bearing as the height is adjusted. The device rotates around the arm axis as the angle changes.

The adjustment plates were cut un the ArcDroid plasma. It did a great job of the curved slots.

The arms were formed from 20mm box section bent on the JD2.

I tack welded the plates to the frame whilst I aligned everything.

The TrakTrike frame tapers towards the front. To ensure the adjustment plates were aligned and parallel I temporarily connected them with M8 threaded rod. 

The pillow block mount was plasma cut and welded. A simple hoop and rod allows the angle of the bearing to change as the arms are adjusted. M8 studs were cut from rod to mount the bearing.

And the bearing mount was welded to each arm.

This mechanism works really well. The steering works as expected with the large handlebars giving plenty of torque, and the height adjustment allows the steering column to be folded down for transport/storage.

There's a full video of the steering build here: