How do I calculate gear ratios

[Syphonics]

I have a set of spurs gears 100:X.
X is driven by a 1:60 worm gear.

How do I calculate X in order to get a total of at least 1:90 gear ratio for all gears added.


Thanks

Similar Threads:

• Help with gear ratios
• Does anyone know the stock X2 mill gear ratios?
• Step motors and Gear Ratios
• Calculating gear ratios?
• How do I calculate my gear ratios?

[Syphonics]

attached reference picture

[Geof]

You need a 1.5 : 1 ratio in addition to your 1 : 60 to have an overall ratio of 1 : 90 so you need 66.6666 teeth driving the 100 teeth. Obviously you are going to have to use 66 or 67 and cannot get exactly 1 : 90 unless you change the 100 teeth gear to something else.

I hope I did the calculation correct.