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#1
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pic: 3 Hour Chassis + 2 Hours
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#2
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Re: pic: 3 Hour Chassis + 2 Hours
If you can I would get the extended output shaft that AM sells and make the center wheel direct drive.
Also how do you plan to tension the chains that your using and what size chain are you looking at? Also the chain runs on the bottom look like they will run into the square tube... In inventor with design accelerator you can generate chain runs so that you can check for clearance. If you in solidworks I think there is a way to do the same thing. Last edited by Jeff 801 : 11-05-2010 at 14:12. Reason: More questions |
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#3
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Re: pic: 3 Hour Chassis + 2 Hours
It's looking a ton better!
You'll need some way to attach the tube supports to your outer plate. We use 1.5"x3/4"x3/4" press-fit stock tapped with 1/4-20 to do this. The tubes should have material underneath them. There's no constraint tool in real life, so spacers have a hard time just hanging there. Think about the assembly process when you're designing robots, that helps me the most. You can usually just pound them through with a gentle persuasion tool if the hole is a tad small. If at all possible, the design would be a lot stronger if you move the tube supports so that they are not all along the same line. Are you running both chains on the same side? Last edited by 548swimmer : 11-05-2010 at 14:08. |
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#4
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Re: pic: 3 Hour Chassis + 2 Hours
I agree, get the tubes to at LEAST be in 2 planes.
Perhaps also consider mounting your battery laying down on the bottom of your robot. That way you don't have to reach through anything. I would also only have the cross supports go to the inner side plates. Use the standoffs and some wood blocks to support the outer ones. |
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#5
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Re: pic: 3 Hour Chassis + 2 Hours
I agree with the direct-drive on the center wheels, that will get all of the heaviest objects directly over your primary drive axle, and close to the center of rotation.
It's hard to tell from your drawing if you have done this or not, but if you chose to, you could eliminate the face plate of the toughbox by machining your 1/8" plates with the proper bearing and shaft holes. |
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#6
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Re: pic: 3 Hour Chassis + 2 Hours
There's a chain reduction, so direct driving the center wheel isn't possible without a gearing change.
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#7
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Re: pic: 3 Hour Chassis + 2 Hours
Good point, but in the previous thread on this topic the OP mentioned making custom gearboxes.
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#8
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Re: pic: 3 Hour Chassis + 2 Hours
Quote:
Or on the back side of that wheel the sprocket is smaller than all the others and after looking at the AndyMark website the smallest sprocket (#25 I am assuming) is 32 tooth and the sprocket on the toughbox output shaft is still 16 that means the overall reduction is 25.5:1 and the top speed is 4.57ft/s From what I know your average single speed robot is ~9ft/s which would cause me to thing there is some sort of difference in the toughbox or the extra chain reduction can be removed and supplemented with one of the many gearing options AndyMark has for sale. After going back to the old thread I see that your wanting to get ~12ft/s which you can do by using the Toughbox with the optional 9.87:1 and direct drive which would give you ~11.82 ft/s Last edited by Jeff 801 : 11-05-2010 at 17:48. Reason: More info |
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#9
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Re: pic: 3 Hour Chassis + 2 Hours
You could consider a 1x1 bar of 80/20 insead of what you have for the cross pieces. The ends can be tapped for a 1/4 20 bolt and you can just bolt it to the outer plate. This also leaves you a lot of flexibilty on the inside as far as mounting other components.
I think it would work nicely in a prototype like this. My team actually used a very similar frame to this this year, aluminum side plates, cross beams extending to the outer plate, toughbox transmission etc...Anyway the 80/20 worked nicely for us on the cross braces. |
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#10
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Re: pic: 3 Hour Chassis + 2 Hours
Quote:
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#11
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Re: pic: 3 Hour Chassis + 2 Hours
Quote:
80/20 is unneccessary if your team CADs well, because you can plan all of your cuts ahead of time. 80/20 can be nice if your team likes to make it up as you go and constantly be taking off and adding parts. (not that you can't do it with other materials, just 80/20 makes it easy). I would still recommend it for a prototype though. |
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#12
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Re: pic: 3 Hour Chassis + 2 Hours
Not really, 80/20 weighs almost exactly the same as 1/8" wall 1" square tubing.
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#13
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Re: pic: 3 Hour Chassis + 2 Hours
Quote:
For the hollow tube in general, you're right. But for the specific hollow tube called for, 80/20 will be heavier. Comment on the cross-braces: I'm not quite sure I'd trust a 1/16" wall for that application in that pattern. Change the pattern, and you'll probably be fine--but run the analysis just to make sure. |
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#14
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Re: pic: 3 Hour Chassis + 2 Hours
Quote:
(These numbers are what SolidWorks is telling me). You can pocket 1x1 tubing, but you can't pocket 80/20 so that could be included in the weight tradeoff. Last edited by sgreco : 11-05-2010 at 19:46. |
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#15
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Re: pic: 3 Hour Chassis + 2 Hours
i would recommend the use of C channel instead of square pipe, it can be just as strong if oriented correctly, and it is lighter as well as easier to attached.
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