Modeling/Sprockets

based on W. E. Johns work. but added offsets to accomidate martin sprocket O.D.s

1. find angle
   • 360/number of teeth=angle between
2. draw polygon with tooth count and diameter from chart
   • draw horizontal and verticle guides
   • click polygon tool and immediately type tooth number
   • click the center intersection, place mouse on verticle guide, type in radius
3. using radius tool draw guides away from verticle at half the tooth angle on both sides
4. using the tape measure tool draw guides the distance of the pitch angle away from the guides just drawn
5. place a circle where the guides intersect on either side of center
   • when drawing the circle place the mouse on the guide back to center
6. draw guides perpendicular at base of the two cricles
7. draw guides offset
   • 7/64 works for 100# chain
8. draw a circle with the center at the intersection of the offset and the original radius guide
   • made the edge meet the edge of the circle opposite of center at its shortest distance
9. repeat on other side
10. delete some of the extra lines and circle parts
    • you can use the corner of the original polygon for the tip of the tooth
11. using the rotate tool copy the profile at the angle then click astrix and then the number of copies
12. as you go you can copy larger sections

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data

http://www.martinsprocket.com/2001/SecEc.pdf