|
|
|
![]() |
|
|||||||
|
||||||||
![]() |
|
|
Thread Tools |
Rating:
|
Display Modes |
|
|
|
#1
|
||||
|
||||
|
Re: pic: Manually machinable one-speed gearbox
To anyone who has run with "Texas Tube" in the past: How do you account for the stretching of the chain over the course of the season? There doesn't appear to be a lot of room for tensioners. Is this even a concern with the lengths of chain that are being used?
|
|
#2
|
||||
|
||||
|
Re: pic: Manually machinable one-speed gearbox
Quote:
|
|
#3
|
||||
|
||||
|
Re: pic: Manually machinable one-speed gearbox
Alright, that's good to know! Now, since this is an awesome thread and I'm learning a lot from it, I'm going to ask another question.
Has anyone every thought about using timing belts instead of chain? Fitting it into a 2x1 box probably wouldn't be possible, but what about a 2x2 box. I'd imagine it would be even more of a "set it and forget it" scenario because a timing belt would be less likely to break than a chain. |
|
#4
|
||||
|
||||
|
Re: pic: Manually machinable one-speed gearbox
Quote:
|
|
#5
|
||||
|
||||
|
Re: pic: Manually machinable one-speed gearbox
This season, 1477 used a Texas Tube style chassis. On a 4WD with all omni wheels, we used VexPro 16t #25 sprockets. We had tensioners on both our practice bot and our competition bot, and never used them on either robot. We had no issues with the 16t sprockets, and our chain runs were more than 200 links long. Game permitting, we will likely be running a Texas Tube style drive chassis again. Our experience with #25 chain in 2x1 tube has been outstanding thus far.
Quote:
http://www.chiefdelphi.com/forums/sh...ad.php?t=94701 Here is a picture of 2791 running timing belts inside tube extrusion. |
|
#6
|
|||
|
|||
|
Re: pic: Manually machinable one-speed gearbox
2791 has continued iterating on their belt-in-tube drive since then. Chris Picone would be the guy to talk to about that.
|
|
#7
|
||||
|
||||
|
Re: pic: Manually machinable one-speed gearbox
192 has also used belt in tube for the past three years. 15mm wide GT2 in 2x2 .125 wall. With our set up and access points it's incredibly fast to assemble and tear down even though you'll never need to.
It is possible to run 15mm wide belts in 2x1.5 but you'd have to bore out the pulleys around the bearings or move the bearings out. I wouldn't recommend 9mm belt in the DT unless you had a proper tensioning system like 971 and even then they have had issues breaking belts. |
|
#8
|
|||||
|
|||||
|
Re: pic: Manually machinable one-speed gearbox
How are your access points for belt in tube set up? How is it assembled?
|
|
#9
|
|||||
|
|||||
|
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. |
|
#10
|
|||
|
|||
|
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! |
|
#11
|
||||
|
||||
|
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? |
|
#12
|
|||
|
|||
|
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. |
|
#13
|
||||
|
||||
|
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. |
|
#14
|
|||
|
|||
|
Re: pic: Manually machinable one-speed gearbox
Quote:
|
|
#15
|
||||
|
||||
|
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. |
![]() |
| Thread Tools | |
| Display Modes | Rate This Thread |
|
|