I adjusted the frame for the front vents and had it all printed, sanded and spray painted. Then I modelled two brackets for connecting it to the body frame. Once I received all the hardware I got it all fixed into place. The blue surrounding panel will be glued to the skins, then I can push the silver vents through from the inside. This way I can still take the skins off the frame if necessary.
After over 40 hours the core part of the center ankle has finished printing. After a bit of sanding with first 60 grit then 120 grit, I test fitted the ankle with the food drive and the foot shell. Only now (after the sanding, of course) I found out that the rounded curvy bit above the pivot point is too close to the foot shell. The pivot point of the ankle and the foot drive didn’t even lign up properly, let alone the ability of the ankle to pivot forward or backward. Also, the center part was too wide and only just wedged into the channel in the foot drive. If I tied the M12 bolt that holds ankle and foot drive together, the ankle didn’t move at all.
So much for tailoring the part to my needs… (see my last post). This morning I changed the 3D model and sent off another print that should be finished in about two days. I don’t think the slight change in design will be noticeable, especially with the center foot under neath the body and hardly on eye-height with anyone.
I continued with the scratch build of the ankle using styrene sheet material. But I had reservation about its rigidity when finished, especially the connection of ankle to body. So I went back to my Rhino 3D model and developed a more strengthened version of the core part of the ankle and started printing it over the weekend. This way I will have less filing and sanding to do and I can tailor the connections to my needs.
For the ankles of the center foot I went back to the styrene scratch build approach that I used on the main ankles and legs. With a few extra 3D printed bits that seemed to work well. As I decided to put the 2-3-2 conversion off for a later date, I will for now fix the center foot to the base plate of the frame. Have to develop a rather sturdy connection as the center foot seems to take most the the bumps in the ground (this according to many discussions in the club’s forum).
Having already done the foot shells for the main feet last year, I was much quicker this time. I still have to come up with a clever and quick way of attaching the the “doors” on either side. This goes for the main foot shells too.
I guess I will try a solution with magnets. They will have to be strong enough to hold the “doors” whilst R2 encounters rough terrain.
The extra days I had off before and after Christmas I used to start on the center foot to eventually have R2 standing on three legs. Unfortunately I didn’t take too many pictures. So here’s one of the assembled foot drive. The castor wheels are from Homebase. The thick styrene parts were part of the A&A kit I ordered last June. It was again a trial and error process to find the right bolts, nuts and washers for all the connections needed. I also ended up filing off bits of the upper part of the drive as it didn’t fit into the center foot shell.
This is still a thing I can’t get into my head. That the foot drive and foot shell of the same kit don’t work together without extra filing and cutting. I know that some builders might only use one or the other but you’d think that they should work together, coming from the same guy.
But once again: it’s building and not assembling!
I got out the bits I had cut for the wooden frame of the body. I originally started with the design by Mike Senna, one of the original builders. No wonder it’s called the Senna frame in the R2 community.
The base and top are made from 18mm ply, the uprights and intermediate rings from 12mm MDF. The wood was kindly given to me by our carpenter’s workshop. Thanks to Keith and his fabulous team. I then had it CNC cut by a company near my work at the end of October.
Most of the connections needed some sanding. That might have been down to the material being 1/2″ and 3/4″ rather than 12mm and 18mm. After a successful dry fit, I started to glue it together with PVA, leaving enough time between the steps for it to properly dry.
The photo shows me being halfway through the assembly. Didn’t take one of the completed frame but you’ll get the idea. I’m sure there’s more opportunities for pictures of the finished frame.