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#1
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Re: Titanium chain & sprokets
We used nylon sprockets on our prototype over the fall. The prototype used a fisher price and a CIM motor on each side of the robot in a six wheel drive configuration. We used AMshifters to give us a top speed of 10 ft/sec in high and about 4 ft/sec in low (off the top of my head). I don't have the torque numbers in front of me but I would say it is comparable to any sort of forces most teams would see on their drive train. We bolted nylon sprockets on the four corner wheels (less load than the center wheels usually). We had 180 degrees of tooth engagement on the sprockets which were 30 tooth and 35 pitch. After a lot of hard testing we had no problems with these sprockets. Not a single tooth was broken and there wasn't any excessive wear. We are not sure if we had any efficiency loss from the nylon sprockets yet,
Note: In the end we decided to lighten steel sprockets for our drive system just to be safe. If your really trying to save weight I would look at nylon or aluminum sprockets. We bought the nylon sprockets (part number 6793K135) from Mcmaster-Carr. We also have bought aluminum sprockets from a local supplier for Azusa . These sprockets are made for go-karts and look really good and strong. Hope this helps, Good Luck!! Last edited by Derek Bessette : 26-01-2005 at 13:28. |
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#2
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Re: Titanium chain & sprokets
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Good stuff. For the uninformed, check this out: http://www.chiefdelphi.com/forums/showthread.php?t=24246&highlight=aluminum+sprocket s Kudos to Joe for sharing this last year. I'm sure lots of people are still reaping the benefits. -JV |
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#3
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Re: Titanium chain & sprokets
Just a little more info on titanium sprockets.
Shimano Dura-Ace ten speed cassettes have 4 Ti sprockets, the four largest sizes vary depending on the cassette. They cost ~$150 (for 11-23) to ~$170 (12-27). This is cost prohibitive very quickly. Also the 7075 Al sprockets are hard-coat anodized (class III) for durability while the Ti is nickle coated for the same reason. However you may be able to get Ti, and definitely Al bike chainrings on sale from some of these places. Think prelightened sprockets. Just don't bogart the Dura-Ace on me Also any one who builds a robot with Campy should win the form over function competition immeadiatly.You can get these from any number of bike cataloges: www.worldcycling.com www.coloradocyclist.com www.supergo.com www.nashbar.com www.performancebike.com Last edited by Cory : 26-01-2005 at 15:08. Reason: fixed your link :) |
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#4
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Re: Titanium chain & sprokets
We used nylon sprockets for our robot's drivetrain last year. We got into pushing matches and we ran at high speeds and they were perfectly fine. If you are concerened that much about wieght i would say use the nylon sprockets. We used steel sprockets in the '02 competition and they were exceedingly heavy even machined out. We also had a couple of them fail. We incorporated nylon sprockets in the same drive train but for last year and they worked perfectly. I would use nylon sprockets for the drivetrain, and then like alreadly said if there are high ammounts of torque needed then you should do calculations to see if it would be beneficial to go for steel sprockets.
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#5
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Re: Titanium chain & sprokets
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These sprockets would also be very hard to work with. All the major bicycle component manufactures have there rear sprockets fitted on a non-standard spline, that would be VERY difficult to machine yourself. Theres also not very much material left over do drill your own mounting holes either. The front chain-rings would be much more easily adapted. Most road chain rings fit on a standard 130mm bolt circle, and the higher quality ones are very light. Mountain bike chain rings are smaller in size, and also have a smaller bolt diameter.(which i don't know off the top of my head) On the other hand you still limited to bicycle chain, which although is 1/2", is much narrower than standard ANSI chain. You also need special connecting pins, to change the chain length, and a different chain tool. Also, you cannot get half-links for it. In summary, it is my opinion that, although very light, high-performance bicycle sprockets are more hassle than their worth. You can get standard aluminum sprockets, and just lighten them yourselves, and they will be just as light as bicycle sprockets, and a whole lot easier to work with. Last edited by Holtzman : 27-01-2005 at 09:17. |
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#6
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Re: Titanium chain & sprokets
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http://www.dura-ace.com/publish/cont...ive_train.html Quote:
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Campagnolo Std Chainring BOLT circle = 135mm Yes they use a 1/2" pitch chain. No the chaintools aren't that special just smaller. No special parts are required you just add or remove links. Bike chains don't use master links. Yeah they make really narrow chain for the 10-speed cassettes that doesn't even work with the 9-speed cassettes. The advantage is you can get it at any bike shop. |
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#7
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Re: Titanium chain & sprokets
Pete;
You are correct on the first point. The teeth are ground to help shifting. As a result of that, you end up with an asymmetric tooth profile, which takes torque better in one direction than the other. I think were both right on that one. We seem to be in agreement regarding rest of my points. I think we've gotten a little off topic anyway. |
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#8
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Re: Titanium chain & sprokets
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