Author Topic: Wheel/Gear confusion  (Read 8083 times)

Tinker

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Wheel/Gear confusion
« on: December 16, 2008, 08:31:36 AM »
I'm a little confused. The pitch circle is what the diameter of the gear would be if it were a round disk. When I make a diagram of a gear train this is fine but, here's my confusion, when teeth are cut into these "wheels" they won't mesh. Do the gear drawing generators account for this or what? I may be putting the horse before the cart as I've not really tried one out yet. I've done some reading but haven't seen this question answered directly. Right now it seems like the more I read, the dumber I seem to get. I appreciate any help and don't be afraid to laugh or call me dumb....I'm blessed with thick skin and a sense of humor. Thanks.

Offline Martyb

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Re: Wheel/Gear confusion
« Reply #1 on: December 16, 2008, 12:27:57 PM »
Tinker,
Here's an exerpt from the "Designing Cycloidal Gears" page located here:
http://www.csparks.com/watchmaking/CycloidalGears/index.jhtml

If you scroll down the page to the first illustration, the dotted circle about mid-tooth is the Pitch Circle.

"Imagine two disks of different diameters rotating against each other without slipping. The outer edge of each disk defines the pitch circle for that disk.

When we put teeth on these disks, the part of the tooth that rises above the pitch circle is called the addendum. In the case of cycloidal gears, the addendum is a curve is an epicycloid . The addendum curve is usually the same on both sides of the gear tooth tip in mirror-image. This is not strictly necessary when a gear train is driven in only one direction. Occasionally the winding wheels of watches are made with wolf teeth. These have an epicycloidal addendum on one side of each tooth tip and a straight or even slightly concave curve on the unused side of the tooth tip. This makes the teeth look like... Teeth! "

Basically, its the point on both gear and pinion where the teeth engage.

Marty

Tinker

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Re: Wheel/Gear confusion
« Reply #2 on: December 17, 2008, 10:10:08 AM »
Well thanks to all who replied here and my other posts. Thanks to Marty I'm now up against the wall. I think I've gleaned more than enough info to build a clock and now it's up to me to do it. I'm intrigued now to see what I come up with. Thanks again.

Offline Umengwabu

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Re: Wheel/Gear confusion
« Reply #3 on: August 13, 2015, 09:03:34 PM »
I look for things like this at this time.

Offline KarlaB

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Re: Wheel/Gear confusion
« Reply #4 on: May 12, 2017, 02:55:24 AM »
Tinker,
Here's an exerpt from the "Designing Cycloidal Gears" page located here:
http://www.csparks.com/watchmaking/CycloidalGears/index.jhtml

If you scroll down the page to the first illustration, the dotted circle about mid-tooth is the Pitch Circle.

"Imagine two disks of different diameters rotating against each other without slipping. The outer edge of each disk defines the pitch circle for that disk.

When we put teeth on these disks, the part of the tooth that rises above the pitch circle is called the addendum. In the case of cycloidal gears, the addendum is a curve is an epicycloid . The addendum curve is usually the same on both sides of the gear tooth tip in mirror-image. This is not strictly necessary when a gear train is driven in only one direction. Occasionally the winding wheels of watches are made with wolf teeth. These have an epicycloidal addendum on one side of each tooth tip and a straight or even slightly concave curve on the unused side of the tooth tip. This makes the teeth look like... Teeth! "

Basically, its the point on both gear and pinion where the teeth engage.

Marty

Thanks for this link, i was looking for it!

Offline panistefanin

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Re: Wheel/Gear confusion
« Reply #5 on: June 05, 2017, 08:09:16 AM »
Hello! this complex question. Here it is necessary to think ...
mybestwestern