Cycloidal Gears Blanks

GregS

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Sep 4, 2008
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Machesney Park, Illinois
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I am hoping someone can provide me with a formula for determining the outer diameter of a gear blank given the module and number of teeth required.
This is for cycloidal teeth for which no existing wheels are available to measure.

Thank You,
Greg Schraiber
 

Wimberleytech

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Jan 27, 2022
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I have constructed a few using an open-source tool called FreeCAD. You have to add the Gear module and then it is as simple as a few clicks. Then you can measure.
Here is the Wiki for the Cycloidal Gear calculations.
Hope this helps a little.
 

Allan Wolff

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Mar 17, 2005
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There are calculators available online, but if you want the formula, it is:
Wheel diameter = Module X (number of teeth + allowance)
wheel diameter is in millimeters
allowance is 2.76 for 17 teeth or greater, 1.61 for 10 to 16 teeth, 1.71 for less than 10 teeth
More details can be found here.
 

GregS

Registered User
Sep 4, 2008
499
17
18
Machesney Park, Illinois
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Region
I have constructed a few using an open-source tool called FreeCAD. You have to add the Gear module and then it is as simple as a few clicks. Then you can measure.
Here is the Wiki for the Cycloidal Gear calculations.
Hope this helps a little.
Wimberleytech, Thank you for the link to freeCAD. I've downloaded a copy and drawn a sample gear. Looks good.
Thanks, Greg
 

GregS

Registered User
Sep 4, 2008
499
17
18
Machesney Park, Illinois
Country
Region
There are calculators available online, but if you want the formula, it is:
Wheel diameter = Module X (number of teeth + allowance)
wheel diameter is in millimeters
allowance is 2.76 for 17 teeth or greater, 1.61 for 10 to 16 teeth, 1.71 for less than 10 teeth
More details can be found here.
Allen, Thank you so much for the formula. Interestingly, this formula produces a diameter value that exacly matches the value derived from FreeCAD. Much Appreciated. Also, thank you for the PDF. Very informative.

I hope to post some photos and a write up for my "novel' gravity escapement and temperature compensated pendulum. I built the escapement and pendulum, before building the clock works because I wanted to make sure it would actually work before designing the wheels/pinions and all the other parts that will make it a real clock movement.

Thanks again,
Greg
 

John MacArthur

NAWCC Member
Feb 13, 2007
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laplaza.org
I hope to post some photos and a write up for my "novel' gravity escapement and temperature compensated pendulum. I built the escapement and pendulum, before building the clock works because I wanted to make sure it would actually work before designing the wheels/pinions and all the other parts that will make it a real clock movement.

Thanks again,
Greg
Greg - Please do be sure to post photos and write-up of your escapement and pendulum. Those of us who are "precision nuts" are always interested.
John MacArthur
 

Wimberleytech

Registered User
Jan 27, 2022
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Great...glad you took the plunge. I have used FreeCAD for about four years and have designed and printed countless useful tools and repair parts for stuff around here. Since my return to watchmaking, I have extended my designs to horological endeavors.
 

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