Lots of progress this weekend, with lots of lessons learned! We manufactured the base and the yaw yoke axis bearing, and mounted the yaw axis on the floor in the basement. We also installed the yaw yoke drive system to test backlash and rigidity.
Yake yoke drive shaft, below:
The drive shaft itself was fairly easy to cut, taking about two hours on the first attempt. The shaft is 1.5″ in diameter at the base and steps down to a 1-3/8″ – 12 thread, then to a 30mm diameter step for the slipring, and finally to a 1-1/8″ diameter for the drive pulley.
The drive shaft attaches on its base to a half inch steel plate, which then bolts on the the frame (the base, in the case of the yaw yoke).
This is the mounted base with the yaw yoke drive shaft attached. The mounting plate is actually welded to the drive shaft. That build process ended up taking a long time, and I think that we’ll need to revisit how to attach the shaft to the mounting plate.
Here is the yaw yoke mounted to the base, with the drive assembly attached. The bearings are almost rigid enough, but not quite. We have some ideas about how to fix that.
The frame itself is also really rigid. There is no noticeable deflection on the base assembly, and deflection on the yaw yoke is minimal.
As always, Hobbes was around to help.
Now on to the biggest problem: the drive chain stretches! A lot. I expected some stretch, of course, but not nearly as much as we are getting. You can grab the yoke arm and push, moving the assembly 5 to 10 degrees with very little effort. Turns out that this is just how chains tend to behave. It’s looking like we are going to have to do a significant redesign of the drive system.
That’s a little disappointing, of course. I at least was feeling fairly confident that we were on the right track with this design. Modifying the drive assembly is going to involve either rebuilding new yoke arms or cutting them apart . Either way, it’s going to take a lot of time… [sigh]