Building a Quick Change Gear Bow, need help.

[boxcarmj]

Is there a relationship between the spindle gear (40T) and the leadsrcrew (12TPI)? Is there a formula I need to work out? Thank-you Mike.

[John Stevenson]

Yes that ratio is what makes the threads.

You have a 12 tpi leadscrew and 40 T spindle gear, if you fit a 40T to the leadscrew it will cut 12 tpi as it's a 1:1 ratio
Fit an 80T and it now cuts 24 tpi as it's slowed down by a 2:1 ratio

In a straight drive train, i.e. just one row of gears any idlers in the middle run don't count as they cancel out.

John S.

[boxcarmj]

Thank-you John.