In my last 3D Printed Land Yacht update I included a YouTube video demonstrating the steering mechanism in action.
When I posted this to my 3D Printing Facebook Group someone pointed out that I might need to angle the steering axle, for a couple of reasons.
The first is to create some positive caster which will make the steering more stable at high speeds. The second is to create some negative camber, so that the front wheel leans into the corner, a bit like a motorbike would.
Another aspect of wheel alignment to improve steering, which you might normally consider is toe in, where the front wheels point inwards a little. However, this isn’t an issue where you only have one front wheel so caster and camber are enough to consider for now.
Beyond Just Caster and Camber
After my initial steering prototype it was obvious to me that as well as introducing cater and camber I needed to take up a bit of slack in the steering by adjusting the steering shaft hole size so it’s a better fit.
As simple as this steering mechanism may seem, it was looking like I’d need to spend many more hours in OpenSCAD redesigning the three main steering parts, the steering arm that holds the wheel, the steering bar that attaches to the servo and the steering joint that attaches to the steering to the wooden dowel chassis.
After dedicating a few late nights to designing and using up plenty of PLA plastic for some more prototypes I think I now have an improved design. It’s still not perfect but it is better and I’ve tweaked the OpenSCAD so that it’s easier to modify when I go though the test, tweak, redesign cycle.
Designing a Low Profile Test Tyre
Last night I was awake until about 2am designing a basic test tyre. The main objective was to ensure that I could fit a tyre to the rim snugly, otherwise a wheel rim redesign would be in order.
As I write this I’m 3D printing the tyre, right behind me using black NinjaFlex. If this tyre is a success (and it’s 87% though so far) then I’ll post some pictures of it. If not, I’ll have to retry and report on it later.
If you think about what I said earlier about camber and the front wheel leaning into the corners, this means that for the front tyre at least I’ll need it to have a curved contact area with the road, so it’s equally in contact as it leans.
For now, low profile will be fine and although I could keep low profile tyres on the back there’s two reasons why I might not.
The first is that it’s simpler if I can use the same tyre design for all three wheels. the second is that with a curved contact area like on the front, rolling resistance will be less and the yacht will go faster.
Of course low profile tyres look cool so I could always provide different tyres for different purposes. We’ll see how it goes. Oh and my MakerBot has just beeped at me so the test tyre is finished. Time to have a look, wish me luck…
Awesome, it worked and it fits great! I’ve just taken a picture so you can now see the tyre fitted to the front wheel at the top of this blog post.
What Next for the 3D Printed Land Yacht?
With projects like this, things never quite go to plan, but it’s still good to have some kind of plan in place so we can visualise a way forward, so I’ll try.
At that point I can probably produce a YouTube video of the rolling chassis rolling down a hill with functioning radio controlled steering.
I need to move the steering servo closer to the steering mechanism I think, so I might design a steering servo mount for that. Then I guess I’ll be starting on the sail mount and mechanism for moving it with the other servo.
Of course, all of the radio components and batteries will need to be positioned within the wooden dowel chassis somehow, so lots of work ahead.
There we go, an example of something else not going to plan 🙂
I’ll get there though and the fun is in the journey. If I wanted ‘simple’ I’d have bought a Land Yacht from a shop, but where’s the fun in that? This way I can upload my designs to Thingiverse, a day I’m really looking forward to, sharing this design so anyone in the world can make it!
Anyway, that’s a little way off, but for now if you want to follow my progress please bookmark my main Land Yacht Project Page where I post all updates and join my Facebook Group, where we discuss this and other 3D printing projects people are doing.
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