My chart for cutting gears doesn't go high enough. HELP

[Jack3M]

I have an indexing rotory table, but, I need to cut 150 teeth and the chart for the plates included only goes up to 50.

Math is my weakest asset and I need serious help here. I need to understand the route to the answer also. So my multifold question is, which plate/tooth selection gets me where I need to be. According to my calculations, ya, right, I need to give 0.6 cranks per cut, which seems way wrong and how do I get 0.6 crank accurately?

Pertinent information:
90 turns for one complete revolution
Plate I 15, 16, 17, 18, 19, 20
Plate II 21, 23, 27, 29, 31, 33
Plate III 37, 39, 41, 43, 47, 49
Their calculation for number of turns is:
90/x=cranks. X=divisions/number of teeth
90/150=3/10 of a turn ......which isn't the same as the 0.6 for pure division
If that is correct how do I get 3/10 of a turn with the plates I have? 6 holes on a 20 line?

As you can see I am very confused. May not have enough information for you to help me. This all pertains to my Mery Engine thread
https://www.homemodelenginemachinist.com/threads/mery-6-stroke-kit.30814/

 

[ruzzie]

9 holes on 15 hole plate
12 holes on 20 hole plate

You were nearly there 90/150 = 3/5 of a turn

http://www.bilar.co.uk/cgi-bin/division-calculator.pl

 

[Jack3M]

Thank you for that link, extremely useful.

 

[PhilL]

Thank you for that link, extremely useful.

Jack,
Do you have a copy of the Machinery's handbook? The dividing head section I have bookmarked in mine because I can't remember the damn formula either.

 

[Jack3M]

Actually, I do and now I should have looked for it. I never considered the book could help with this. Dang book is a gold mine. I use it every day I machine I think. '

That link above is better, faster, doesn't allow me to make math mistake, just input errors

 

[PhilL]

I never thought there would be "an APP for that." But I shouldn't be surprised either.