|Red Rover, Ant Weight Combat Robot: Page 2|
I then continued to work the opening and "bore" it out using a grinding stone on my dremel tool that just happened to be ~ 16mm. I had to be careful to only remove the internal honeycomb and not damage the sheet of 1/32" fiberglass on the other side.
After much tinkering to get this process down I decided to add a little bit of reinforcement to the motor mount. I cut out circles of fiberglass cloth the same size as the motor mount hole and after liberally applying standard plastics epoxy to the area I dropped the cloth in and moved it around with a q-tip till it was well saturated and positioned evenly to center..
After letting all the holes cure I drilled out a Large hole for the shaft and two smaller holes for the motor mount hardware. I had to add SS Washers to the mounting screws, but with them the end result was surprisingly strong and when you factor in that the two motors together weigh in at ~2.3 oz that means the entire side wall in the photo to the right weighed in at only .4 oz. later on when I end up shortening the length of these side walls by nearly 2 inches its even less.
At this point I turned my attention to the front and back walls of the build. these two walls where made from the cutting board plastic. I cut them down and drilled them out for the aluminum center posts, and then I drilled out even more materiel just to bring down weight. I also measured out the width of my robot and made slots for the motor mount side walls to slide into once these walls where attached to a base.
However at this point I started to notice a few issues I was going to have to deal with sooner or later. My weight was already getting fairly close to 16 oz and I didn't even have the second set of motors yet. I knew that the rough cut aluminum base plate was to thick and thus far to heavy and would be swapped out later for a lighter material but I also noticed that I was wasting a lot of space and could shave off quite a bit of build material if I shortened the whole robot a bit. at this point I stopped and pondered for a few days. I didn't want to make a rash decision and cut down my materials but I also knew I had to do something.
It took me a bit and several drafts, but I decided that not only would I shave off the access, but that I would also remove the lifting arm servo from the build and shorten the whole robot by nearly 2 inches. Around this same time I also decided that I was not going to have the weight for two separate experimental wedges so I came up with the spring wedge idea that would allow a single wedge to have "give" in all directions from hard impacts.
At this point I also started work on some of the electronics. First thing was to chose a gage of wire that was capable of carrying 4 amps for the motor leads, and 8 amps for the battery to ESC connection, but I also had to chose the lightest that could carry that load so I set off weighing in 18" of all the different wires I had at my disposal. I ended up using a heavy duty servo wire for the motor connections, and a bit of high quality braided 20 AWG Silicone wire for the battery connection. The silicone wire was a hair heavier than I would have liked but I was only using a single inch of it so decided it was worth the extra potential current to the ESC.
You would think that an ESC designed for ant robotics would take weight seriously. but the stock Ant 150 ESC had over .15 oz of wasted materials that had to be de-soldered from the board. I cut out everything that was not needed, bringing the 9 wires that lead from the ESC to the Rx down to just the 5 that where actually needed to carry power and 3 signals. Unfortunately I think I may have toasted the flip control during my de-soldering job.
Tip to ESC developers,.. feel free to provide the Rx wires,.. just don't pre solder them on, that way the builder can chose length without having to deal with de-soldering and trying to get wires back into holes filled with old solder.