Then a few weeks later at the scout hut meeting George was chatting and told me he couldn't find any suspension or drive train components to proceed with the build. I duly said I would take a look at it and see if I could McGiver something together, because if he went the rock crawler route he would probably be looking at some big bills. He had acquired a battered Tamiya race car chassis and thought maybe some of the parts might be usable.
This was the start of Mission Impossible!!! This 3d printed truck weighs over 6 kgs without any of the bits for bonnet/seats/battery etc so whatever needed to be built would have to be able to stand the weight.
Here is the photo of the chassis after I had started work
Anyhoo, I thought I would go with the traditional leaf spring approach, took some of the Tamiya bits, and constructed a front suspension and steering, and found that the 3d printed components were bending under load so had to strengthen it with aluminium angle.
OK that was the front suspension and steering sorted. Then I started on the rear suspension and back axle. There was no way I was getting involved in designing and building a differential so I opted for a straight forward set of bevel gears on a 2:1 ration and duly ordered these from Amazon/China. I specifically ordered both cogs with 5mm bore to suit the threaded rod I was using.
Meanwhile I used the same spring suspension that I had used for the front suspension for the rear, and designed the back axle in a traditional form. When the gears arrived they were big and chunky and would handle the load, BUT the large cog had a 8mm bore! I duly complained to amazon and got a refund for that cog, and then I got to thinking maybe I could sleeve the cog from 8mm to 5mm, and found some brass tube online that would do precisely that. The only issue was that I would have to drill the tube so the gear grubscrews would still work and after a certain amount of foul language and frustration managed to get it sorted.
Then to assembly and alignment which involved four attempts at designing and printing the axle to get everything to fit and not bind but after several days it all came together.
I designed the axle in one piece and then split it horizontally for assemby, and finally it all came together and worked
The end result is a truck with steering, very stiff suspension (it's not going to do obstacles or rock crawling) and a drive train. PHEW!
This is what it looks like ready for George to get on and do the pretty stuff.
And I'm so happy to see the end of that.
Alwyn
