So it’s been a long time since my last post, but it’s because so much has been accomplished! This time I’m going to have some very rewarding pictures that go up, but to make it all more digestable and navigable I’m going to split it up into a few separate posts.
In this post I’m going to cover the building of the actual feet from the parts I went over cutting out previously as well as attaching them to the legs.
The actual assembly of the feet wasn’t particularly difficult, as at this point I have spent many hours gluing and bracing and reinforcing using the Weldon #3 that cements the polystyrene plastic together. Instead, the problem was mounting the motors.
As you can see in the picture the slopes pieces have a gap underneath them where the motor, sprocket, and wheel all will mount. Getting them into this tight space and aligned was far from easy. It took a lot of expanding the initially drilled holes with the dremel to give the motor enough wiggle to sit in the correct spot, as seen below.
This picture is from much later in the process once everything was set up correctly, and as you can see I needed several washers and a lot of wiggle room in the motor mounting to line it all up. The chain itself was a problem too – it turns out that the ones I got didn’t come with a master link attachment, as it is a standard replacement part for an electric Razer scooter. This meant I had to buy a pair of separate master link items off of amazon, wait for them to ship, and then get help from my dad to break the chain and then close it again to the correct length. As luck would have it I got the length on one off by a link at one point and had to re-do the process, later once I started to test the motors.
Once I had the motors in the feet, though, I couldn’t help but want to get them attached to the legs. One step closer to getting him standing, and even walking! To do that, after some consideration and advice from my dad, I decided to use wooden dowels. We went to the hardware store and got some .5″ thick ones, thinking that we would need something beefy to ensure the stress put on it while turning didn’t snap it. I’m still a little nervous about this choice, but worse case scenario if it does break, I should be able to force it out and replace it with a sturdier piece of metal. In order to hold the dowel in place and not slide around I drilled a hole into the very end of the dowel rod, inserted a split pin, and then used pliers to bend the end.
At this point, with the drive feet attached to the legs, I needed to get to work on the center foot. The center foot, however, was much, much, easier to get together (at least at first). This consisted of simply assembling the frame and then using a tap to tap a drilled hole in it that I would screw a caster wheel, i.e. the wheel on a grocery cart, into. Spoiler alert: when I put weight on the caster wheel it actually bent and warped the plastic it was screwed into, completely ruining the threading in the plastic and making the wheel lopsided. In order to fix this I went out and bought strips of aluminum, drilled and tapped them, and glued them onto the plastic aligned with the previously drilled hole for the caster. The hope being that by distributing the forces further out along the foot I prevent this issue from recurring. Again, I am concerned about the wear + tear and the forces that will be put on these joins once I start driving, but until I know the points of failure it’s hard to prepare properly. Especially since it’s so laborious to get the bare minimum done, haha.
There was also one last issue with the center foot to be sorted out – it turned out some of the pieces didn’t line up correctly. Likely due to a combination of factors such as imprecise cutting on the band saw, prints that didn’t come out 100% to scale, and poor measuring skills. I just want to say, for the record, that this would have been a lot easier with a professional workshop, rather than whatever tools my dad has around from building our house 20 years ago. That said, here’s the damage:
I had to cut the once solid piece into two halves, and then use the side pieces to hold them together. Without this there simply was no way to get the sides to properly align on the outside of the foot. To be honest, I’m just glad the fix for this was relatively simple because when I very first noticed I nearly had a panic attack as I was running out of time to get R2 standing before I had to leave and wouldn’t have access to my dad’s tools anymore.