Minimizing chain noise

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Re: Minimizing chain noise

Post by swbluto » Jun 06 2010 12:40pm

Miles wrote:If minimizing noise is important, then just avoid using chain for the first stage of a two stage drive.
But plastic chains showed promise?

The only trick with them is that they seemed to be only usable with a total high gear ratio because they excelled more in speed than tension, but the kind of sprockets available for #40 limits the first stage gear ratio. I'm guess the second stage with #40 could probably attain 3, and the first stage with #40 could probably attain 4 suggesting a total gear ratio of 12 possible.
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Re: Minimizing chain noise

Post by dumbass » Jun 06 2010 12:48pm

Many years ago when I was much younger and more foolish I bought a new Ford Pinto. Actually I eventually owned 2 of them and a friend had one as well. They had a "timing belt" to drive the cam. This damn belt had to be replaced every 12k to 15k miles. My friend would always call me to help do his. So between the 3 cars I was replacing a belt at least every 3 months. Now I have owned a lot of cars that had standard metal timing chains and in hundreds of thousands of miles I never replaced a metal timing chain.

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Re: Minimizing chain noise

Post by Miles » Jun 06 2010 12:52pm

swbluto wrote:
Miles wrote:If minimizing noise is important, then just avoid using chain for the first stage of a two stage drive.
But plastic chains showed promise?

The only trick with them is that they seemed to be only usable with a total high gear ratio because they excelled more in speed than tension, but the kind of sprockets available for #40 limits the first stage gear ratio. I'm guess the second stage with #40 could probably attain 3, and the first stage with #40 could probably attain 4 suggesting a total gear ratio of 12 possible.
What advantage does a plastic chain have over a belt?

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Re: Minimizing chain noise

Post by swbluto » Jun 06 2010 12:57pm

Miles wrote:
swbluto wrote:
Miles wrote:If minimizing noise is important, then just avoid using chain for the first stage of a two stage drive.
But plastic chains showed promise?

The only trick with them is that they seemed to be only usable with a total high gear ratio because they excelled more in speed than tension, but the kind of sprockets available for #40 limits the first stage gear ratio. I'm guess the second stage with #40 could probably attain 3, and the first stage with #40 could probably attain 4 suggesting a total gear ratio of 12 possible.
What advantage does a plastic chain have over a belt?
Significantly higher ceiling on tension and torque transmission? Easier to implement sprockets are widely available and "fixing things" in the field should be easier and less costly than a belt, if a chain were to break than if the belt breaks (Which has happened to me many times). Each time a belt breaks, it costs me an entire replacement belt which has averaged at about 23 dollars. Each time a chain breaks, it costs a replacement link which is... what... 10 cents? Also, I believe plastic chains are more compact.

I'd need to examine the torque capability more closely though - I've only seen torque/motor-teeth-count figures on HTD and the "ult. tensile strength" figures on plastic chain. I also know that HTD types tend to generate a bit of noise at high speeds, but it seems likely plastic chains wouldn't be exempt from this.
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Re: Minimizing chain noise

Post by Miles » Jun 06 2010 12:58pm

swbluto wrote: Significantly higher ceiling on tension and torque transmission?
Oh, come on............. :)

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Re: Minimizing chain noise

Post by Papa » Jun 06 2010 1:20pm

liveforphysics wrote:
Papa wrote:
liveforphysics wrote:Do you really think any e-bike appliction would ever need a stronger chain than simple #219??? How many belts have we seen skipping or broken or whatever else, and who has ever had #219 (or even #35) fail for anything? You and throw graphs and charts away, the motorsports world has done 50+ years of real-world testing, and the proof is inherent. :P
And speaking as a pro wrench, one of the biggest money-makers of the 70's and '80's was timing chains - typically at 25k to 40k they had either wore-out or failed completely - and not from lack of lubrication or tire smokin' abuse either. I bought a '73 Civic and drive it 103,000, negligent miles on its original 'belt'. But examples aside, the original issue the OP raised was not one of reliability or longevity... but noise. So what's your suggestion(s) to his dilemma?
Honda is an excellent example :) They used belts for a few decades because they were silent. Right now, Honda doesn't use a belt for any engine (at least that I'm aware of). They moved to Honda silent chain with the advent of the F20C in the Honda S2000. Reason? Belts become/became pretty substantial reliability problems with monster cam lobes and stiff triple valve spring setups. Toda and other companies released various kevlar timing belts and things to relieve the problem, but things would still get pretty sloppy by around 5-10k miles of running on big lobes/springs.

After the move to silent chain (a chain with no rollers or contacting pins to click), folks get multi-hundred thousand miles and the chains are still like new. You can run as big of cam/spring combo as you like on the F and K-series engines and never worry about belts shredding or skipping teeth etc. You do need to change to a smarter chain-tensioner design though... I hate the Honda auto chain tensioner setup... But the chain/sprockets themselves are outstanding, extremely quiet, pretty fine pitched, and handle loads of RPM and power. :) I put mine through 10,000rpm drive sprocket speeds dragging along some pretty brutal lobes against mean triple springs, and every time I tear into the engine, the chain looks brand new. :)
This is all 'rosy-n-cozy' but you haven't directly addressed swbluto's original question - noise.
dumbass wrote:Many years ago when I was much younger and more foolish I bought a new Ford Pinto. Actually I eventually owned 2 of them and a friend had one as well. They had a "timing belt" to drive the cam. This damn belt had to be replaced every 12k to 15k miles. My friend would always call me to help do his. So between the 3 cars I was replacing a belt at least every 3 months. Now I have owned a lot of cars that had standard metal timing chains and in hundreds of thousands of miles I never replaced a metal timing chain.
How odd?? I was the head wrench on the Parker brothers 2WD, rear engine buggy class during peak, Firecracker 250 offroad racing season in Barstow, California. VW motors were dumped in favor of 2300cc Pinto motors. I would religiously inspect the timing belts prior to every event, and we not only had NO mid-race belt failures, but frequently put 2 and 3, 250 mile races on the same belt. Further, belt technology has vastly improved in the last 15 years, so the 'Pinto' example is not-at-all representative of today's belts.
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Re: Minimizing chain noise

Post by swbluto » Jun 06 2010 2:13pm

Miles wrote:
swbluto wrote: Significantly higher ceiling on tension and torque transmission?
Oh, come on............. :)

Okay, I'll do some calculations to make comparisons.

A 15 tooth has a rating of 5 NM with a 5mm HTD 15mm belt. With a radius of .7 inches, that implies a tensile rating of 280 newtons. #40 plastic chain has a rating of 290 newtons. Egads, so tensile strength is not really the problem, then, is it?

No, the problem is that you'd have to use a 30-tooth motor sprocket and a 120-tooth pedal sprocket in order to handle the torque and get a first stage reduction of 4. 120 tooth HTD sprockets for the pedals is a little bit too big (and unfind-able)... whereas 14-tooth #40 sprocket only needs a 56-tooth #40 sprocket to get a ratio of 4, which is widely available as bicycle front chain-rings.

I need to calculate chain speeds, however, to check if the plastic is suitable. I haven't calculated speed for a 14-tooth #40 sprocket running at 5000 RPM. Anyone know the radius of a 14tooth #40 sprocket?

#40 is code for "bicycle chain", btw.

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Re: Minimizing chain noise

Post by swbluto » Jun 06 2010 2:29pm

okay, so I found a 16tooth sprocket with a pitch radius of 1.25 inches. I then assume a 14-tooth sprocket has a pitch radius of about 1.1 inches which is 0.02794 meters. That's a circumference of .175 meters.

At 5000 RPM, that's 875 meters per minute. According to google, that's 2870 feet per minute which is uncomfortably close to its rating of 4000 feet per minute.

The tensile strength at 20NM is 20/.02794 = 716 newtons = 160 pounds. Okay, that definitely exceeds the plastic chain's rating of 65 pounds. I wonder where I was getting the "27ish pound" figure from earlier?

So, quick detour, plastic chain won't work either. *tears* My motor will *definitely* be putting out at least 15 NM at startup, and 20 NM is realistic.

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Re: Minimizing chain noise

Post by MitchJi » Jun 06 2010 2:41pm

Hi,
bandaro wrote:so, if i was going to walk into my local store, to get a strong (peaking at around 7-8hp from stall) and relatively quiet if possible chain, what would be a good brand and/or type?
#25 with at least a 14t drive sprocket will be quieter than #219 and more than strong enough:
swbluto wrote: I've only seen torque/motor-teeth-count figures on HTD
Where?
swbluto wrote: I need to calculate chain speeds, however, to check if the plastic is suitable. I haven't calculated speed for a 14-tooth #40 sprocket running at 5000 RPM. Anyone know the radius of a 14tooth #40 sprocket?

#40 is code for "bicycle chain", btw.
The equation you need is for the circumference of a circle:
circumference = 3.14 (pi) * diameter

circumference of the sprocket is 14 * 1/2" (pitch) -> 7"
7" circumference / 3.14 -> diameter = 2.229"
Best Wishes!

Mitch


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Re: Minimizing chain noise

Post by Papa » Jun 06 2010 2:58pm

I thought this discussion was primarly about 'noise'?

IIRC, somewhere between 14-16 tooth, 1/2" pitch sprockets is the dividing line where noise dramatically and sharply increases. To see what's actually happening you need to visualize the dynamics. In the simplest explanation I can muster;..

Envision the first chain pin FULLY engaged in the sprocket, and the following (next-in-line) pin, just entering the gap between the teeth. As the fully seated pin rotates around the sprocket, the following pin actually accelerates towards the root just prior to seating. This collision of the pin with the root of the sprocket, and the resulting vibration, is what you hear. Just increasing sprocket tooth count (and/or reducing pitch length) above this 'critical' zone, dramatically lowers the pin's radial acceleration rate and you'll decrease the noise.
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Re: Minimizing chain noise

Post by swbluto » Jun 06 2010 3:27pm

MitchJi wrote:
swbluto wrote: I've only seen torque/motor-teeth-count figures on HTD
Where?
It's another one of those "I clearly remember seeing it but where?" situations. But, for your curiousity, there are some ratings in the page at http://www.flennor.de/uploads/media/Powergrip_LL_03.pdf for newtons. Solving for NM is as simple as multiplying by the pitch radius. So...

With a radius of .015 meters for a 14 tooth timing pulley, a 200 Newton rated (As in for the 14 tooth 10mm width version of the 5mm htd) would have a torque rating of 200*.015 = 3 NM. They give a "torque factor" of 1.58 for the 15 mm version, so you multiply that by 1.58 to get 4.74 NM.

To get the torque output of the motor, it's as simple as using my simulator and looking at the graph.
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Re: Minimizing chain noise

Post by Miles » Jun 06 2010 3:28pm

swbluto wrote: #40 is code for "bicycle chain", btw.
No, it's not.

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Re: Minimizing chain noise

Post by swbluto » Jun 06 2010 3:28pm

Miles wrote:
swbluto wrote: #40 is code for "bicycle chain", btw.
No, it's not.
Picky, picky. The converse is, anyways.

I was just letting the bicycle people know I was talking about "everyday" chain and sprockets. :)
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Re: Minimizing chain noise

Post by Miles » Jun 06 2010 3:29pm

swbluto wrote: A 15 tooth has a rating of 5 NM with a 5mm HTD 15mm belt. With a radius of .7 inches, that implies a tensile rating of 280 newtons. #40 plastic chain has a rating of 290 newtons. Egads, so tensile strength is not really the problem, then, is it?
This is complete rubbish. You haven't a clue... :)

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Re: Minimizing chain noise

Post by swbluto » Jun 06 2010 3:31pm

Miles wrote:
swbluto wrote: A 15 tooth has a rating of 5 NM with a 5mm HTD 15mm belt. With a radius of .7 inches, that implies a tensile rating of 280 newtons. #40 plastic chain has a rating of 290 newtons. Egads, so tensile strength is not really the problem, then, is it?
This is complete rubbish. You haven't a clue...
I know that I wasn't calculating the "true tensile rating". I was simply stating from those hypothesized calculations that tensile strength wasn't a good comparision, which it isn't.

What I do have a clue about is the tooth size needed and the absurdly large pulley sizes required.
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Re: Minimizing chain noise

Post by Miles » Jun 06 2010 3:32pm

Why pick a 15t pulley to compare with #40 pitch chain :roll:

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Re: Minimizing chain noise

Post by MitchJi » Jun 06 2010 3:34pm

Hi,
Papa wrote:I thought this discussion was primarily about 'noise'?

IIRC, somewhere between 14-16 tooth, 1/2" pitch sprockets is the dividing line where noise dramatically and sharply increases. To see what's actually happening you need to visualize the dynamics. In the simplest explanation I can muster;..
Matt's experience with #25 it is good as long as he uses at least 14t (not as quiet as a belt but ok).
Luke wrote: After the move to silent chain (a chain with no rollers or contacting pins to click), folks get multi-hundred thousand miles and the chains are still like new. You can run as big of cam/spring combo as you like on the F and K-series engines and never worry about belts shredding or skipping teeth etc. You do need to change to a smarter chain-tensioner design though... I hate the Honda auto chain tensioner setup... But the chain/sprockets themselves are outstanding, extremely quiet, pretty fine pitched, and handle loads of RPM and power. :) I put mine through 10,000rpm drive sprocket speeds dragging along some pretty brutal lobes against mean triple springs, and every time I tear into the engine, the chain looks brand new. :)
Papa wrote:This is all 'rosy-n-cozy' but you haven't directly addressed swbluto's original question - noise.
Isn't silent chain the next best option after a belt for noise?
swbluto wrote:From what I read, it [silent chain] states that it requires an oil bath and an "automatic tensioner". Those would seem to be difficult if not impractical to implement on an ebike. Also, where would one find sprockets for these things (Since they have their own special sprockets)?
I don't see why it requires better lubrication than any other chain.

I was under the impression that they recommend either a tensioner or adjustable distance between the shafts. Once its set correctly I don't think its more prone to stretching than any other chain.

But what's the problem of implementing a tensioner on an ebike (2 skateboard wheel tensioners) ?:
Image
Image

I agree (shooting from the hip) that plastic chain isn't a good idea.
Best Wishes!

Mitch


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Re: Minimizing chain noise

Post by swbluto » Jun 06 2010 3:36pm

Miles wrote:Why pick a 15t pulley to compare with #40 pitch chain :roll:
A larger driver pulley would've necessitated an impractically large pulley to get an equivalent gearing ratio to chain, maybe? I'm sure it's fine when you're directly driving the wheel, but I'm talking about at the crank shaft and the compatible widths available is limited by the chain stays.

Btw, eyeballing the N ratings earlier, it looks like a 28 tooth pulley would merely double the torque rating of a 14 tooth drive. Oh boy, 9 NM.
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Re: Minimizing chain noise

Post by Miles » Jun 06 2010 3:38pm

swbluto wrote:
Miles wrote:Why pick a 15t pulley to compare with #40 pitch chain :roll:
A larger driver pulley would've necessitated an impractically large pulley to get an equivalent gearing ratio to chain, maybe?
So, how are you going to cope with the sizes when you want to get an equivalent reduction with #40 chain?

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Re: Minimizing chain noise

Post by swbluto » Jun 06 2010 3:43pm

Miles wrote:
swbluto wrote:
Miles wrote:Why pick a 15t pulley to compare with #40 pitch chain :roll:
A larger driver pulley would've necessitated an impractically large pulley to get an equivalent gearing ratio to chain, maybe?
So, how are you going to cope with the sizes when you want to get an equivalent reduction with #40 chain?
We're not comparing with plastic chain anymore, are we? It's already been determined HTD and plastic chain is unsuitable (And they appear to comparable in the severity of unsuitability).

With metal, easy: torque rating on a 14 tooth >> HTD 14 tooth torque rating.

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Re: Minimizing chain noise

Post by Papa » Jun 06 2010 3:46pm

MitchJi wrote:Isn't silent chain the next best option after a belt for noise?
For me?... no. By going with belt, I eliminate the infamous 'leg tattoos' and noise... and trimmed-off 1.8 pounds of oily baggage in the process! :mrgreen:
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Re: Minimizing chain noise

Post by Miles » Jun 06 2010 3:47pm

swbluto wrote: We're not comparing with plastic chain anymore, are we? It's already been determined HTD and plastic chain is unsuitable (And they appear to comparable in the severity of unsuitability).
I thought we were. So, is this about noise, or not?

HTD is unsuitable for what? Give a specific example. What is the maximum driver pulley speed?

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Re: Minimizing chain noise

Post by swbluto » Jun 06 2010 3:50pm

MitchJi wrote: I was under the impression that they recommend either a tensioner or adjustable distance between the shafts. Once its set correctly I don't think its more prone to stretching than any other chain.
I believe Luke and the "chain source" both state "automatic tensioners", which sounds like a more specialized version of a regular "tensioner".

If that's not the case, then I don't see what else could be the problem. I'm guessing it requires as much lubrication as other chains, although the "oil bath" seems a little extreme. The fact it's "wider" also seems like it'd use more oil, too.

The only problem now is finding available "silent chain" sprockets.

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Re: Minimizing chain noise

Post by swbluto » Jun 06 2010 3:57pm

Miles wrote:
swbluto wrote: We're not comparing with plastic chain anymore, are we? It's already been determined HTD and plastic chain is unsuitable (And they appear to comparable in the severity of unsuitability).
I thought we were. So, is this about noise, or not?

HTD is unsuitable for what? Give a specific example.
My scooter. :lol:

Above 5-6 NM, it breaks the belt. Although I'm sure that's partially attributable due to the non-perfect setup, the fact that it doesn't break at lower torque levels suggests the belts rating is being exceeded (Note, I've since reduced the current level to lower the motor torque so it's not breaking it anymore). This experience is corroborated from the technical figures in the catalog I linked to in the previous sheet, and extrapolating from that to a 20 NM motor suggests general difficulty. There might be a possibly workable combination (Like 25mm-width 5mm pitch,driving pulley teeth of 20, and limiting the motor torque to 12 NM - 4 kW at 30mph only needs 7-8 NM.), but it'd be too close to the "edge" for my comfort given each belt would probably cost at least $30. I'll continue looking into, though. Btw, noise levels on a belt and chain at 4000 RPM really isn't *that* much different according to data-sheets I saw.

And, yes, it's about noise. But it's more specifically about something that'll work with the performance requirements and is the quietest of that group. If it's too weak, fuhgetaboudit.

But... now that I'm thinking about, maybe an 80-100 tooth timing pulley might fit in the crank area (With more difficulty to install, of course.). My 60 tooth timing pulley has a diameter of, maybe, 4 inches.
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Re: Minimizing chain noise

Post by Miles » Jun 06 2010 4:03pm

What is the maximum speed you need for the driver pulley?

8M PowerGrip GT3 should be ok at 6000 rpm

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