Posted by BillS on October 06, 2007 at 20:09:18:

In Reply to: Fellows 6A rack cutter posted by Enrique Cabrera on October 04, 2007 at 01:24:50:

I'm scratching my head over the formula you showed. I don't know why the number of pinion teeth would have anything to do with cutting the rack.

Looks like the formula would be used to cut the number of teeth in the pinion, not the rack.

Besides, you don't need to use DP in the numerator and denominator, since it cancels out.

Seems like the formula for a rack should be something like this:

Change Gear Ratio = Constant x (Teeth in Cutter) x (Circular Pitch of cutter)

where Constant is based on the circular pitch of the rack table drive gear which is probably multiplied by some additional fixed gear ratio built into machine. Once you know it, the Constant value should be the same for any rack/pitch.

I'm shootin' in the dark here, so maybe somebody could jump in ??