Metalworking (rec.crafts.metalworking) Discuss various aspects of working with metal, such as machining, welding, metal joining, screwing, casting, hardening/tempering, blacksmithing/forging, spinning and hammer work, sheet metal work.

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Old July 17th 03, 02:11 AM
Dave Baker
 
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Default Sprocket cutting

Subject: Sprocket cutting
From: (Claude P)
Date: 17/07/03 00:03 GMT Daylight Time
Message-id:

Hi guys, could anyone tell me what would be the best way to cut a 5
teeth sprocket for a 3/8 pitch chain.


Yes, don't. That's not enough teeth for a sprocket to work properly.


Dave Baker - Puma Race Engines (
www.pumaracing.co.uk)
"How's life Norm?"
"Not for the squeamish, Coach" (Cheers, 1982)


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Old July 17th 03, 04:21 AM
Roy Hauer
 
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Default Sprocket cutting

Not enough teeth for it to work properly, don';t waste your time.


On 16 Jul 2003 16:03:21 -0700, (Claude P) wrote:

x-Hi guys, could anyone tell me what would be the best way to cut a 5
x-teeth sprocket for a 3/8 pitch chain.
x-Thank you in advance.
x-
x-Claude.


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Old July 17th 03, 07:44 PM
Koz
 
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Default Sprocket cutting

That sprocket is only .6380 pitch diameter. On most chains, by the time
you get the depth for the bottom diameter you would have no room at all
for a bore.

The worst part, however, is the chordal speed variation. Because the
chain travels around the sprocket as a series of chords rather than a
smooth level, there is a speed variation imparted either to the sprocket
(as an idler) or to the chain (if the sprocket is driving) with each
tooth engagement. In this case that speed variation is 19.1%. In some
cases this speed variation is enough to essentially beat the system
apart. (picture beating the system with a dead blow hammer at 19% of the
load with each tooth that engages)

Another side affect of this speed variation is harmonics. If you hit
the right speeds with it, it will send some nasty harmonic vibrations
down the chain and cause a high degree of whipping. Most people get
beyond this by increasing tension...the end result of this is generally
to wear things out in short order.

Koz

Claude P wrote:

Hi guys, could anyone tell me what would be the best way to cut a 5
teeth sprocket for a 3/8 pitch chain.
Thank you in advance.

Claude.



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Old July 18th 03, 02:01 AM
Claude P
 
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Default Sprocket cutting

Thanks for your responses.
As it turns out I found another sprocket and now have to make an eight
teeth sprocket. The maximum rpm for this sprocket will be 7000 rpm.
can this still be done with an eight teeth sprocket or should I
consider gearing down some other way? What about a torque converter?
Is there one for small engines? Can I build one?
Claude.

Koz wrote in message ...
That sprocket is only .6380 pitch diameter. On most chains, by the time
you get the depth for the bottom diameter you would have no room at all
for a bore.

The worst part, however, is the chordal speed variation. Because the
chain travels around the sprocket as a series of chords rather than a
smooth level, there is a speed variation imparted either to the sprocket
(as an idler) or to the chain (if the sprocket is driving) with each
tooth engagement. In this case that speed variation is 19.1%. In some
cases this speed variation is enough to essentially beat the system
apart. (picture beating the system with a dead blow hammer at 19% of the
load with each tooth that engages)

Another side affect of this speed variation is harmonics. If you hit
the right speeds with it, it will send some nasty harmonic vibrations
down the chain and cause a high degree of whipping. Most people get
beyond this by increasing tension...the end result of this is generally
to wear things out in short order.

Koz

Claude P wrote:

Hi guys, could anyone tell me what would be the best way to cut a 5
teeth sprocket for a 3/8 pitch chain.
Thank you in advance.

Claude.




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Old July 18th 03, 03:25 AM
Kenneth W. Sterling
 
Posts: n/a
Default Sprocket cutting

On 17 Jul 2003 18:01:57 -0700, (Claude P) wrote:

Thanks for your responses.
As it turns out I found another sprocket and now have to make an eight
teeth sprocket. The maximum rpm for this sprocket will be 7000 rpm.
can this still be done with an eight teeth sprocket or should I
consider gearing down some other way? What about a torque converter?
Is there one for small engines? Can I build one?
Claude.

Koz wrote in message ...
That sprocket is only .6380 pitch diameter. On most chains, by the time
you get the depth for the bottom diameter you would have no room at all
for a bore.

The worst part, however, is the chordal speed variation. Because the
chain travels around the sprocket as a series of chords rather than a
smooth level, there is a speed variation imparted either to the sprocket
(as an idler) or to the chain (if the sprocket is driving) with each
tooth engagement. In this case that speed variation is 19.1%. In some
cases this speed variation is enough to essentially beat the system
apart. (picture beating the system with a dead blow hammer at 19% of the
load with each tooth that engages)

Another side affect of this speed variation is harmonics. If you hit
the right speeds with it, it will send some nasty harmonic vibrations
down the chain and cause a high degree of whipping. Most people get
beyond this by increasing tension...the end result of this is generally
to wear things out in short order.

Koz

Claude P wrote:

Hi guys, could anyone tell me what would be the best way to cut a 5
teeth sprocket for a 3/8 pitch chain.
Thank you in advance.

Claude.


It would probably help to know what you are building.... 7K is pretty
fast, even for a belt. You may want some kind of a gearbox.
Ken.



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