Gear calculation help please

[chucketn]

I am making a custom fine feed banjo for my 7x14 lathe. Ihave 20 and 80 tooth gears, from a laser printer, that are the same mod as the7x change gears that I want to use.
Is there a formula to calculate the center to centerdistance of meshed spur gears? I would like to lay out the holes for the gear axelswithout having to allow for adjustment for tooth mesh, making the attachment ofthe banjo via a clamp on the lead screw bushing.
Chuck

 

[Woodster]

This any help to you? - http://www.cage-gear.com/spur_gear_calculations.htm

 

[chucketn]

Yes sir! That's what I needed! Thank you Woodster!
Chuck

 

[Jasonb]

Those table sare best suited to DP gears

IN your case PCD = Number of teeth x MOD

so to get ctrs add the two PCDs and divide by 2

 

[chucketn]

I figured that out, Jason. I converted Mod to DP and went from there. I'm a imperial type and have to convert from metric to figure things out.

Chuck