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Timing belts vs Chain


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Jtepper



Joined: 04 May 2009
Posts: 44


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Timing belts vs Chain

I went too the bearing place today, to look at timing pulleys, and they guy there showed me the book that he could order them in from, but then quickly had me convinced that sprockets and chain would be cheaper, more efficient, more compact, and MUCH easier to repair for only slightly more weight, so why are timing belts so much more popular then chain in robo wars? only potential issue i can see is the chain coming off if the chassis gets bent, but surely if it gets bent enough to kick the chain off then your allready in serious trouble. Oh btw a setup with belt and pulleys is around $160 compared too $70 with chain, for 6 small sprockets 2 bigger ones and the chain/belts

Post Mon Aug 10, 2009 7:37 pm 
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Glen
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Joined: 16 Jun 2004
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chain is much cheaper and easier to remove. it also stretches a pretty considerable amount (mine did anyway im sure a proper setup isnt so bad) and its heavy as.

most of us that use timing belts also use tiny brushless motors with 5 and 6mm shafts. and your damn lucky if you can find robot sized sprocket with a 5/6mm bore. plus you are asking for serious trouble trying to dangle a chain and sprocket combo off one. not to mention you can attain much greater gear ratios with the belts.

the belts both V and timing are alot more tolerant of misaligment. saying oh well if its bent it would be f**ked anyway isnt good enough in the arena Wink you gotta plan for anything.

we get ours here. the pair of pulleys and belts slides in at < $100 usually.

http://www.automotsys.com.au/nuova.html

thats not to say you couldnt use a chain at all. badger has one and does just fine with it. and aside from the stretching i didnt have much trouble with my chain drive.

just have to weigh up the pros and cons of every setup.
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Post Mon Aug 10, 2009 7:55 pm 
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Nick
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Joined: 16 Jun 2004
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Location: Sydney, NSW


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Most smaller bots use aluminium timing pulleys; if the guys was comparing steel pulleys and sprockets, then yes, there would be only a small weight difference.

Chain is better when its travelling short distances. If you can keep the sprockets close and maybe ad in a tensioner, then the chain is much less likely to come off and stretching is less of a problem.

V belts have an advantage that they can act as a clutch to reduce stress to the weapon motor

Post Mon Aug 10, 2009 8:49 pm 
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Rotwang
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Joined: 15 Jun 2004
Posts: 1589
Location: Vic


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We like chain Smile
As Glen said Badger uses a no 25 chain to drive his spinner weapon.

Weasel uses no 25 for his drives as do Ultidrum for his drives, the rental bots and arena sweeper and our ref bot.

They all use chain drives but they are lightweights or bigger.

Fragmentor uses pushbike chain for his hammer mechanism.

And yes as Nick said V belts to give a bit for spinning weapons.


We tend to use chain for drives when it is doing multiple things as in it’s the gearbox and transferring the power to multiple wheels, it sort of helps justify the expenditure of so many weight points.

Out featherweights almost always have only 2 drive wheels so gear motors lighter, easier, and more compact.

Don’t have anything against timing belts but apart from the primary stage of arena sweepers drive and MiniMowers weapon we haven’t come up with a design that needs them.
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Post Mon Aug 10, 2009 9:18 pm 
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maddox



Joined: 21 Dec 2006
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Location: Belgium


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Chain has 1 big advantage, you can make it to fit, and not being dependent on the delivery times of a firm.

Post Tue Aug 11, 2009 1:20 am 
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