Quote:
Originally Posted by YawnYao
You guys have an awesome robot this year. I have a few questions about the cad though.
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Hi Yawn,
Thank you for the compliment, we worked incredibly hard this season!
Here are the answers to all your questions. I've categorized them in terms of the different systems, hopefully the answers explain everything you wanted to know.
Gorilla Arm (Intake Arm):
-Pivot Shaft inserts were made on the lathe using black ABS.
-For long standoffs/axles, we first end face the stock on both ends in order to have as close to a round number as possible (measured using tape measure). We then machine it to size accordingly using digital read out on our lathe, taking off necessary material after squaring up against a face.
-Extrusion Bushing was a custom made part in house. We first machined it on the lathe using black ABS, and then drilled the mounting holes using a vertical mill.
-Arm sprocket is a standard Vex Pro 54T 35 chain plate sprocket that we lighten in house using a CNC mill.
-The inside plate bushing is pressfit and secured using gorilla glue. During competitions as part of our pit checklist, we do push it back into place in case it is starting to pop out.
-Intake arm pivot veraplanetary gearboxes are cantilevered, but they held up throughout the whole season. The only issue we had was tightening the bolts too hard (Mounting the gearbox to the plastic extrusion). We fixed that by extending the aluminum gussets further upwards as you see in the cad, so that the aluminum supports the gearbox.
-We decided to omit the mechanism to push the ball back into intake. The idea was to push the ball out in case we wanted to score low goal, after it was in our popper. For weight reduction, and knowing that we can score in the high goal just as fast as low goal, we decided to remove this mechanism all together. That being said, if we did decide to score low, we simply closed our popper roll cage when intaking so that ball stays in conveyor area at all times instead of going into the roll cage area.
Electrical System:
-The camera mount was 3D printed in 2 pieces, and then assembled together using gorilla glue (hot glue during competition repairs). 2 Pieces are the ring, and the camera holder. We went through a few iterations in order to make it structurally sound, paying attention to the grain created when printing, the infill, and making sure it’s printed accurately. Ring was printed with the lip facing up, base was printed as if the camera is looking down. The camera mount dampener was also 3D printed using a soft polymer TPU Filament (Company: Ninja-Flex, Material Name: SemiFlex)
-The camera we used was a Microsoft webcam:
https://www.microsoft.com/accessorie...nema/h5d-00018
-Router was mounted mostly with velcro and zipties, initially we did create a mounting plate for it, but we ended up mounting it directly to one of our gussets near the popper.
-The talons were mounted closer to PDP compared to CAD, allowing the wires to actually go through the slots. All electronic components were mounted onto the lexan using mushroom cap Velcro.
-The slots on the battery holder had the intention of securing the battery connector from the main breaker/PDP. We didn’t end up using that method but we do ziptie our battery power connectors securely every match.
Chassis:
-Bumper mounts included 1/4 -20 bolts (not in CAD) which acted as threaded standoffs or studs. Once the bumper was placed down onto the chassis, we fastened them down using wing nuts on the 8 exposed standoffs (4 per bumper piece).
-The chassis skiis were machined in house on CNC mill using Chlorinated PVC (CPVC). This material was donated to use from a sponsor, and we found it to be very versatile in terms of its use, bumper mounts were also made out of this material.
-Plastic Bellypan is made of 1/16” thick ABS, CNC’d on our router table, and flanges were folded in house on our breakpress.
-We had major problems with using hex bearings in 2014 on our drive train with them exploding. Thus, we chose to use 1/2" round bearings in our bearing blocks on drive. We had to choose between keyed sprockets, or keyed on the wheel end (we went with this option). For machining these axles accurately, we first use hex stock on the lathe and machine the features. We then secure it onto the vertical mill, and using an edge finder, and 1/16” endmill, we machine the keyway. The tapped hole is machined with a hole drilled using the mill, and then tapped by hand.
-The drive chain tensioners are sprung to different gussets which attach the shooter assembly to the drive chassis. All drive chain tensioners push down on the chain. We used surgical tubing with all our tensioners.
Conveyor:
-The square disk part on conveyor assembly is to prevent the belt from popping out when ball is being funneled on a more extreme angle.
Please let me know if you have any more questions!