The past few weeks I have been finalizing the last parts of BOB’s assembly. Last week (which I couldn’t make a blog post for because I was studying for the SAT) I tapped the end cap’s holes for the short shaft penatrators. I realized that some of the 4 holes I tapped were crooked. This was REALLY BAD, because the parts threading into those holes needed to lay flat for proper o-ring sealing. I figured out a workaround for this issue. I drilled out clearance holes to remove the threads and used a nut. This was a better solution than the tapped holes (because the threads are somewhat a wear feature that should be both steel and replaceable), however this wasn’t possible because the threads of the penetrators were too short on these specific parts to go entirely through the end cap. To solve this, I slightly weakened the rear end cap by plunge milling a recess (I’m not sure if this is the right term. But the feature I machined is essentially a very wide, shallow counter bore to give clearance for the nut). This feature exposed 3 threads on each penetrator, which is enough for effectively full loading on these threads. The end cap should still maintain structural integrity because the original design had a 3x safety factor (2 times the industry standared 1.5x safety factor), and I only removed 0.02″.
I also ordered several pieces of hardware that we were missing for the ROV. I then used the drill press and the depth stop to fix the clearances and counter bores for the thruster mounting hardware. The tolerances were most likely thrown off by the resin in the printer being expired.
I then came in early and installed all the thrusters. I then cleaned all of the thruster’s penetrator’s o-rings, and installed all of the penetrators in the end cap. Then I did the same for the power penetrators, the depth sensor, the plugs, and the vent cap. For the Ethernet cable, I re-spliced each of the 8 wires very neatly before installing the penetrator.
Next I was working on the floatation that I have been building this summer. I cleaned the epoxy off of some parts of the floatation that need to be re-coated. I also used the heat gun to soften some of the parts to press them flat after the epoxy had warped them.
I also worked on the thruster cables inside the tube. Me and Miles went back and forth between how the cables will be set up. The two options we looked at had either a connector about 3 inches away from the end cap, with a cable going from that to the boards, or re-splicing the cables to plug into the boards. After spending 2 hours soldering half of the first option, we decided to switch.
I had to switch to another depth sensor because the cables had gotten messed up beyond my repair skills. I then crimped some .1in clip connectors for the depth sensor and crimped Anderson Powerpoles for the power plugs.
We went to the club and activities fair and might have recruited some people 🙁
