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Team 1671: Off-season belt drive prototype
rev 1 rev 2 rev 3Here is the prototype that the 1671 CAD team has put together. It is driven by two standard tough box transmissions (for now). The dimensions are 26.1 inches wide X 36.75 inches long, and only 5.46 inches tall. It uses timing belts instead of chain to power the wheels.(sprockets and belts from sdp-si) The system was inspired by team 1625's internal belt drive, and the tensioning system was modified from team 114's, the cool thing about it is the ability to tension the belt system externally. We would love to hear what you guys think about the design. Thanks :) |
Re: Team 1671: Off-season belt drive prototype
Looks like a great drive base! We used a timing belt drive on our Lunacy robot and it was rock solid. We're still running it as a development and demonstration base. Ours actually doesn't have a tensioning system though.
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Re: Team 1671: Off-season belt drive prototype
Thanks, the team has worked really hard.
Really, that is great to hear. Yeah a lot of our mentors have been bringing up belts for a couple years now, and we wanted to take a different direction in 2011. They also save a lot of weight if your sprockets are good. |
Re: Team 1671: Off-season belt drive prototype
I'm not going to comment on the use of timing belt, as our team hasn't had experience with it. I do, however, have a few general questions and comments.
What size axles are you using? They look like 3/8", but I'd highly suggest 1/2" for cantilevered wheels. Also, What is the point of the diamond shaped bearing blocks? It would be much better for manufacturing if they were simpler. Other than that, looks pretty cool. Good luck! |
Re: Team 1671: Off-season belt drive prototype
Yeah, all of the axles are 1/2" with cantilevered wheels 3/8" would be really bad. :eek:
As far as the diamond shape it was mainly for looks, team 114 used a simpler square sliding block, we may need to change this when we begin manufacturing, but we will definitely look into that. Thanks |
Re: Team 1671: Off-season belt drive prototype
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I'm with eugene, make them square. I'd also say lose the pocketing on the crossmember and switch them to 1/16" wall. I can see why with teh slots you can't run 1/16" on the siderails, but I'd recommended losing the pocketing there as well. There is a lot of work invested in such pocketing, and without much gain. Heavily pocketed 1/8" is actually weaker than solid 1/16", and often a bit heavier. |
Re: Team 1671: Off-season belt drive prototype
Yeah they have been modified to be square now, it was a really simple fix.
This is our first time using aluminum tubing (and welding) usually we are a 100% sheet metal design. I will definitely fix the tubing. Do you know of any good sites to purchase square and rectangular tubing with a 1/16 inch thickness. I just got the ones on the bot from Mcmaster, but for 1/16 inch tubing they only have 1inch X 1inch. Thanks |
Re: Team 1671: Off-season belt drive prototype
Shaker's working on a pretty similar prototype (but even shorter!). Insert your favorite variant of "great minds think alike" here.
I too think the lightening is a bit of a stretch. Taking material out of the sides (especially the sides perpendicular to forces in a box tubing scenario) weakens it a LOT. Considering you can cut a bunch of weight with square bearing blocks I would do that. If you can think of a way to tension the blocks without using sliding bearing blocks, you can use unpocketed 1/8" tube to support your bearings. A lot of teams ran cantilevered wheels off of Toughbox Nanos last year which are made of the same stuff. This could save you a little weight and a lot of strength considering how aggressive your pocketing is around the bearing blocks. However, unpocketed 1/8" tube for a whole rail is pretty hefty, so you may want to use 1/16"... but 1/16" of material is not a lot to hold a bearing with! |
Re: Team 1671: Off-season belt drive prototype
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There are other great metal suppliers in CA, but we've always been happy with Coast. Maybe ask 1323 what they use, they're much closer to you as you know. |
Re: Team 1671: Off-season belt drive prototype
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In fact, we use 1/8" purely because of the sliding blocks, and it's usually the only 1/8" on our robot! |
Re: Team 1671: Off-season belt drive prototype
Thats cool that you guys are doing something similar, I hope you post it up.
Yeah I see what you are saying about the thickness, 1/8 without pocketing would weigh a considerable amount. But I need to make sure I can find a supplier for the tubing we need (2inch X 1inch, and 2inch X 1inch) that has those dimensions in 1/16inch thickness. |
Re: Team 1671: Off-season belt drive prototype
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Re: Team 1671: Off-season belt drive prototype
I am not familiar with welding parts. Is it okay to use 1/8inch on the outside rails, and 1/16inch in the support bars?
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Re: Team 1671: Off-season belt drive prototype
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I'm a big fan of efficiency. If you have to use 1/8" for the siderails, yes you *could* pocket it, but often that time and resources is better spent elsewhere. We compensate for this by extremely aggressive in parts that are easy to add pocketing to (all the plates that we get waterjetted, where pocketing is trivial to add). Although we get our framerails CNCd because we get a lot made, we have them designed such that they could be made on a manual. Don't get me wrong, it's a good start, just trying to help you out. Just curious, why have the double opening frame? You may want to close one end, if the game switches back to 06-09 bumper rules, you'll need some support there anyway. you may want to design in 6" segments on the intake side for that reason as well, and a bumper support system for the siderails. Never hurts to figure this stuff out a head of time so that it is well integrated into your design. |
Re: Team 1671: Off-season belt drive prototype
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