2025-06-15

Last modified: 2025-06-16 14:57:46

Tractor

We picked up some used primary school chairs for free.

I put one over the chassis box and had Lucy sit on it, and saw where her feet ended up.

I think in order for both her and I to be able to drive it, the seat position is going to have to be adjustable.

I have made a start on the steering mechanism.

The steering axis will be inclined by 10 degrees, I have 3d-printed a 10-degree angle block, and started turning kingpins.

The turned-down section is 16mm diameter, that will be the kingpin part, then a thrust bearing, then the fat part. The fat part will be cross-drilled (at 10 degrees) to take the spindle, which will be welded in place. The spindle needs to be 16mm to go through the wheels, and some larger diameter to retain it (probably just a washer and split pin), and then whatever diameter to suit the cross-drilled hole.

And then there will be an arm at the top connected to a track rod type thing. The arm will probably be aluminium made on the CNC machine, with a split clamp to hold it to the kingpin. Unsure if that will be able to grab hard enough, I guess I'll find out. Can add a key if not.

Update: both kingpins made and cross-drilled at 10 degrees. I used the CNC vice on the pillar drill to hold them while drilling, it worked pretty well.

Yes there is a couple of mm difference in the height of the fat section, I obviously made some sort of blunder, never mind.