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#1
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pic: Offseason Drive Idea
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#2
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Re: pic: Offseason Drive Idea
How does this improve the serviceability of the drivetrain over a WCD, given that you need to remove the output shaft of the gearbox in both setups?
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#3
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Re: pic: Offseason Drive Idea
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Another nice feature is that to pull the gearbox, one only needs to slide it about an inch in after removing the bolts, as opposed to the full length of a WCD-style output shaft. |
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#4
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Re: pic: Offseason Drive Idea
I think this is a great idea, it saves a lot of space for the electronics, but i think you should consider that this makes you CoG higher, increasing the change of your robot tripping. Also the cims are way more exposed out there, and you should consider that. The cables coming out of the cims will also be out there, you should check if they wont leave the frame perimeter or get bent too much. Where they are right now unfortunate accidents could happen, even if the chance of someone messing up your wiring out there is low you shoud be very carfeful with that, some teams tend to have the worst luck during the regionals. At NYC this year our main braker was exposed and a team managed to accidentally hit it in a way that it turned our robot off, so i suggest making a case for the cims and the wires if you keep that design.
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#5
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Re: pic: Offseason Drive Idea
If you are really concerned about packaging, I would get rid of the 2x1's on the outside of wheel well and replace it with .25 in plate, or get rid of it (WCD axle's are cantilevered; outside support not necessary.)
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#6
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Re: pic: Offseason Drive Idea
These aren't WCD axles, they're dead axles (except for the center, which is a live hex axle coupled rotationally to the gearbox output shaft).
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#7
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Re: pic: Offseason Drive Idea
I don't know about dead axles but with live axles you can replace the box tubing on the sides with plate tubing. I'll try to find a photo of it if you wish to see.
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#8
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Re: pic: Offseason Drive Idea
My team had a similar idea for the gearboxes this year, putting 3 CIMs on the outside of the drivebase.
Here's a few shots of the gearbox: https://drive.google.com/folderview?...&usp=sha ring In our experience, it works quite well for keeping the COG low and keeping the weight on the outside. The gearbox and CIMs are also very accessible. There's quite a bit of force on the inner gearbox plates though (the entire gearbox is essentially resting on them), just something to bear in mind. Here's what our robot looked like at the end of the season: http://www.chiefdelphi.com/media/photos/40089 Texas Torque did a similar gearbox last year, too. They used WCD. You can see a shot at 53s. http://youtu.be/dSjHFgbcJZc Last edited by JoeyL : 14-04-2014 at 19:27. |
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#9
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Re: pic: Offseason Drive Idea
It is a good start. Here are a few questions though:
Why not get rid of the unnecessary metal on the inner gearbox plates? Leave some meat around the upper bearing and the get rid of the rest. Why did you place the pulleys on the outside of the wheels? For turning, stability, and other purposes it would be better to get the wheels out the extra ~1" on both sides. Is your center pulley wide enough to fit 2 belts side-by-side? All the pulleys appear to be the same size. CG does seem high, but depending on the game this may not matter. If you need essentially no ground clearance (this year), you can have your battery sit about a 1/2" off the ground. [Legally] Max your bumpers out to 20lbs and place them as low as legally allowed. How are you bolting the chassis and it's components without collapsing the tube? It is not typically a problem with 1/8" walls, but every now and again you will have someone not paying attention and keep cranking on the bolt because they can still turn it. |
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#10
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Re: pic: Offseason Drive Idea
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Last edited by Oblarg : 14-04-2014 at 22:36. |
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#11
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Re: pic: Offseason Drive Idea
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#12
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Re: pic: Offseason Drive Idea
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Eli, nice design. I hope you post a more finished version when you've cleaned up the CAD and models. Maybe even a pretty render for us? ![]() I hope to see something similar coming out of your team for competition in the future. |
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#13
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Re: pic: Offseason Drive Idea
We used 3/16" aluminum rivers with steel mandrels to hold our chassis together this year - I don't think we're ever going back. They are simple and lightweight.
Another option is Rivet nuts (riv-nuts). They are exactly what they sound like. You can get them from McMaster (94020A335) and other places. |
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#14
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Re: pic: Offseason Drive Idea
If COG is a concern, you could do an 8 wheel drive and rotate the gearbox 90 degrees provided you move the belts to the inside of the drive rail, and design the mounting plate of the gearbox as a frame element.
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#15
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Re: pic: Offseason Drive Idea
I'm really not all that concerned about CG; the highest point of this whole assembly is ~10'' off the ground.
Re: Pulley sizes, after toying around a bit I'm pretty sure I'm going to keep them all the same size, for ease of replacement. Making the outer pulleys smaller involves either greatly complicating the wheel spacer arrangement (which is very simple right now) or having the wheels out-of-line, and moreover requires that you keep more backups. |
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