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Unread 14-04-2014, 22:33
Oblarg Oblarg is offline
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AKA: Eli Barnett
FRC #0449 (The Blair Robot Project)
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Re: pic: Offseason Drive Idea

Quote:
Originally Posted by tim-tim View Post
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.
I fully intend to do this; this is just a rough draft I banged out in an hour or two. The extent of the gearbox plate design was essentially copy-pasting projected geometry from a WCP 3CIM dog shifter and a WCP 3CIM single-speed into a single sketch and then toying with it until the center-to-center on the gears was correct, and adjusting the outline.

Quote:
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.
Good point, I'll change that.

Quote:
Is your center pulley wide enough to fit 2 belts side-by-side? All the pulleys appear to be the same size.
The center pulley can fit two 9mm belts side-by-side. The outer pulleys would be narrower on the actual thing, but to save time while doing this (again, rough draft) I just copy-pasted the center wheel assembly.

Quote:
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.
My general solution to this is either a) hover over the students while they assemble it and remind them or b) make wood inserts. I prefer a), since b) adds weight and is a pain. It is 1/8'' wall + gusset plate thickness, though, and I'm pretty sure I saw someone shear a 1/4-20 bolt head off at 449 putting a similarly-constructed thing together without crunching the assembly.

Quote:
Originally Posted by Henrique Schmit View Post
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.
All good points. I did make sure to leave myself a fair bit of breathing room so that I can keep the wires inside the frame perimeter - I find securing them to the body of the motors with zipties works wonders. I'm not so worried about high CG with this given the low clearance of the chassis above the ground.
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Member, FRC Team 449: 2007-2010
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Last edited by Oblarg : 14-04-2014 at 22:36.
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