|
|
|
![]() |
|
|||||||
|
||||||||
![]() |
| Thread Tools |
Rating:
|
Display Modes |
|
#61
|
|||||
|
|||||
|
Re: pic: Manually machinable one-speed gearbox
Been running belt in a tube structure formed from sheet metal for the past three years with no issues. The sheet metal works great because we can start with a readily available belt/sprocket combo and size the tube accordingly, rather than the other way around. Access is achieved by opening up the entire side of the tube, which makes installation a lot easier than the through-the-end approach or small access pockets required by extrusion.
It is a fair bit larger than the texas tube approach, due to the increased sprocket diameter/width, and the need to add additional clearance for the rivets which hold the tube together, but it works well with our resources, and we like the insurance it provides. Last edited by Joe G. : 15-05-2015 at 01:57. |
|
#62
|
|||
|
|||
|
Re: pic: Manually machinable one-speed gearbox
One thing I want to make clear is that with the Texas Tube approach, it is almost physically impossible for the chain to jump off the sprocket if assembled correctly, because of the constraints of the tube. For failure to occur, the chain would have to essentially break, the risk of which can be minimized by not using masterlinks. Even if the chain loosens and rubs against the tube after a lot of usage, it will still probably be safe (as the other teams have noted, all these robots have been through multiple regionals and championships, and in the case of 118 some very defense heavy games like 2013 and 2014).
Other benefits include: -Low maintenance (basically assemble and never touch again for the rest of the season) -More space and weight efficient -Relatively simple, no special equipment besides a mill required -Keeps things clean and out of harm's way (the number of times I saw noodles getting stuck in the chains of other teams was too much to count, because of Texas Tube, we had virtually no problems driving over and around the noodles). -This has more applications than just the drive train! |
|
#63
|
||||
|
||||
|
Re: pic: Manually machinable one-speed gearbox
Quote:
![]() Above is an image of 192's 2014 base about to be welded up. There are two rectangular holes on the tops of each side as well as 4 holes in the side in addition to the bearing holes. First the belts go in the rectangular holes in the top, then the pulleys are slid into the side holes and rolled down the tube to their bearings holes. The gearbox is put on, axles are put through the pulleys, bearings popped in, and wheels are put on. Assembly time is about 5 minutes a side. |
|
#64
|
||||
|
||||
|
Re: pic: Manually machinable one-speed gearbox
Quote:
I don't understand. This thread talks about 2x1x.125 tube being used for Texas Tube. Why would we have to "settle" for 1/8" wall? |
|
#65
|
|||
|
|||
|
Re: pic: Manually machinable one-speed gearbox
Quote:
Drawing a quick 36" tube in Inventor I had the following weights: .1" wall 2x1 Versa Tube: 1.97lbs. (0.65lbs. per foot) .125" wall 2x1 tube: 2.4lbs. (.8lbs. per foot) .125" wall 2x2 tube: 3.3lbs. (1.1lbs. per foot) It all depends on what you have planned and are building on top. We had 2x1 Versa tube uprights coming off of our setup so 2x2 tubing worked very well for us. With the extra space it also can make mounting off of the tube a little easier and you can lighten the tube to bring the weight down a little. My personal preference would be a lightened 2x2 tube but that's just me. Last edited by BrendanB : 15-05-2015 at 08:28. |
|
#66
|
|||
|
|||
|
Re: pic: Manually machinable one-speed gearbox
Quote:
|
|
#67
|
||||
|
||||
|
Re: pic: Manually machinable one-speed gearbox
Quote:
Quote:
I do have more questions though. How would you get a continuous loop of chain without a master link? My team has only ever used master links with our chain. Last edited by Dan Petrovic : 15-05-2015 at 10:09. |
|
#68
|
|||
|
|||
|
Re: pic: Manually machinable one-speed gearbox
Quote:
http://www.team221.com/viewproduct.php?id=70 Follow these steps: http://www.billetboard.com/showthrea...oul-Chain-Tool First year using one and it was one of the best things we purchased this year. We had 50+ feet of 25 chain on our robot and only had four master links where our elevator platform connected to the chains. Using lighter chain (25 over 35), no master links, and C-C distances has really make working with chains an easy process and eliminated a lot of my worries in the past two seasons in our mechanisms.Last edited by BrendanB : 15-05-2015 at 10:19. |
|
#69
|
|||||
|
|||||
|
Re: pic: Manually machinable one-speed gearbox
We did #25 chain in 2x2x.125 tube on our drop-center 6WD this season and had a good experience. No maintenance all season. There was some chain slap against the tube initially (16T sprockets and long chain runs; not a real problem but noisy), so we slid in a strip of UHMW to dampen that and now you'd never know.
We used a 2x2 because the frame rails in our design had minimal cross bracing due to the large opening for acquiring game pieces. |
|
#70
|
||||
|
||||
|
Re: pic: Manually machinable one-speed gearbox
So it sounds like the consensus here is that to do a Texas Tube design, you must keep all of the axles horizontally inline, and just put smaller diameter wheels on the outside to create a "drop center." I've been throwing together designs in CAD for different drivetrain styles, and I wonder if someone can explain to me if this would or wouldn't work:
![]() (sorry for the poor render quality) Rather than dropping the center or raising the outsides, I did both. I lowered the middle 1/16" and raised the outsides by 1/16", to end up with a "drop" of 1/8". From everything I can see and read, this would fit very snugly into a 1x2x.125 tube. It's completely COTS and would let you use 4", 6", or really any other size wheel anywhere on the drivetrain -- which is big for teams with few resources. General specs: 2"x1"x.125" aluminum tube AndyMark Toughbox-Mini gearbox (alum plate cut down slightly) 17t #25 Team 221 dual sprocket |
|
#71
|
||||
|
||||
|
Re: pic: Manually machinable one-speed gearbox
You can also use omni wheels on the outside wheels, especially in a game with little or no pushing and defense like this year.
|
|
#72
|
|||||
|
|||||
|
Re: pic: Manually machinable one-speed gearbox
Quote:
In fact, our entire setup is very similar to this, with only a couple differences: -- we used 2x1.5x.125 tube -- we used VexPro 16t #25 sprockets |
|
#73
|
|||
|
|||
|
Re: pic: Manually machinable one-speed gearbox
Did you have the issue that 118 mentioned earlier of the chain grinding on the outer bearing race?
|
|
#74
|
|||||
|
|||||
|
Re: pic: Manually machinable one-speed gearbox
Quote:
Here is a technical drawing of (an early version of) our drive tube. Last edited by Nate Laverdure : 15-05-2015 at 13:28. |
![]() |
| Thread Tools | |
| Display Modes | Rate This Thread |
|
|