interesting, I’ve never heard of nylon hex shafts. We swapped our main pivot one to steel to try to reduce slop and damage.
67 is not an over the bumper intake. They simply have a single roller that folds out to assist their under the bumper intake be more full width. If this fold out roller broke, they would still be able to intake and play.
I’m curious if anyone has any “Deploy time” targets. How fast do you design to go from stowed to fully deployed and also the other way around?
When we mostly recently did it, were we using all electric, and I was trying to get to 200-300ms, but I think practically it was more like 500ms.
If we have to do it again I’d still try for 200ms, and I might recommend the students go for a fast rack a pinion or telescoping elevator style rather than a rotating assembly.
the response I got from one of our programmers was “It’s an ‘as fast as possible’ and you tune it to go fasterer”
I guess that’s not very helpful
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Nope - not really. 
but that’s ok, thank you for responding!! I like to have targets so I know when I’m done!
I originally set a goal of 1 second at the slowest (we had a quokka style arm), so I did a bunch of math to get a gear ratio that would allow us to rotate the arm 90 degrees in about 0.5 seconds (Just a guess because I don’t have the notebook I did the math in). I don’t think we ever measured it, but going frame by frame on a youtube video I think it was around 0.6 seconds. A bunch of different factors probably affected the time like my math being based on constant torque (torque decreases with speed) and always fully accelerating (not the case with a PID), energy losses including slightly misaligned sprockets, friction from note dust, and inaccurate weight of the arm in CAD compared to what we built. We also didn’t get the ratio we wanted because some of the maxplanetaries were out of stock, so we just went with the next closest ratio.
Never said it was. I would consider it a hybrid design (albeit, primarily under the bumper) that combined the best of both functions. IMO the root question here is: “Why would you use one type of intake over the other”. Each option, under or over, has it’s advantages and disadvantages; I was simply pointing out that 67s approach appeared to combine the advantages of both while eliminating most of the weaknesses (aside from, maybe, overall weight).
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I wish I had the opportunity to see 9483 in person this season after seeing their matches at champs. Their robot as a whole was very impressive and I would also would have loved to get a a closer look at their intake design as the intake seemed to be very robust and quick to feed to both their shooter/ prep for amp scoring. Easily one of the best over the bumper intake utilized this season in my opinion.
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Wear-Resistant Nylon Hexagonal Bar 1/2" Size McMaster-Carr
TheMoreYouKnow.jpg
Definitely buying some, thanks!
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Wanting to revive this thread a bit. Our team is looking at doing an OtB intake this year. My take away’s from this thread are:
- 1/4" Polycarb
- maybe 1/16" aluminum backing
- heavily debate nylon or steel hex stock for live axles
- and dead axle stub shafts
Can anyone provide some insight on these stub shafts:
- what part, or supplier was used?
- could this dead axle be tapped tube stock with washers?
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For a deadaxle, we just use a short piece of hex shaft with bearings and a tapped end to mount it to a plate. What do you mean by tapped tube stock with washers?
Same thing essentially but fixed to the plate, with washers on the other side of the plate. I thought the dead axle didn’t spin but things spun around it. But makes more sense that it actually spins. Tapped hex stock would be our preferred method anyways.
The hex shaft itself does not spin. The bearings are for the things that do spin around it.
Oops wrong reply, that was meant for @Maroon_Golf
Thank you, Max. These posts provide a lot of clarity, and many things to ponder.
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