If I were going to place two spur gears on a plate such that they meshed, would the distance between their centers simply be the sum of half the gears' pitch diameters? That's what I gather from Machinery's Handbook.

Ex:

gear A is a 64 tooth gear having a diametral pitch of 16 meshes with gear B, a 20 tooth gear.

Pitch Diameter of A = 64/16 = 4

Pitch Diameter of B = 20/16 = 1.25

So I would place their centers (4+1.25)/2 = 5.25/2 = 2.625" apart.

And given the clearance is .157/diametral pitch = .0098, the centers need to be correct to within a a shade under .0049.

Ok, assuming that's correct, I have a metal plate all blued up. I centerpunch a divot for the first shaft. What's the right way to locate the other shaft, assuming it has to be at some odd angle from the first (not purely vertical or horizontal?

I'd be tempted to clamp the gears to the plate, meshed, with the teeth spaced by a few (?) thicknesses of aluminum foil, and use a transfer punch to mark the center of each gear.

Ex:

gear A is a 64 tooth gear having a diametral pitch of 16 meshes with gear B, a 20 tooth gear.

Pitch Diameter of A = 64/16 = 4

Pitch Diameter of B = 20/16 = 1.25

So I would place their centers (4+1.25)/2 = 5.25/2 = 2.625" apart.

And given the clearance is .157/diametral pitch = .0098, the centers need to be correct to within a a shade under .0049.

Ok, assuming that's correct, I have a metal plate all blued up. I centerpunch a divot for the first shaft. What's the right way to locate the other shaft, assuming it has to be at some odd angle from the first (not purely vertical or horizontal?

I'd be tempted to clamp the gears to the plate, meshed, with the teeth spaced by a few (?) thicknesses of aluminum foil, and use a transfer punch to mark the center of each gear.

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