Paul,
A 12 DP is a pretty big tooth profile. I think your teeth may be smaller than 12DP. The Logan QC I made gears for recently, had 20DP, 20 degree PA gears in it. The change gears on the end were 18DP. I have this 1880's Prentise Brothers lathe that has a few broken teeth in one of the back gears which is a fairly coarse tooth gear and it is a 14 DP.
I determined the DP size with a gear pitch gage.
I forgot to mention that I used an 8" rotary table mounted on edge of my Bridgeport. I placed a #3MT arbor in the center hole in the R-table and held it tight with a draw bolt. The arbor had a 1/2-20 thread extending from it. I stacked my gear blanks on it and tightened the nut on the end of the arbor to hold the blanks. I had no keyway to hold the blanks.
Charlie W.
A 12 DP is a pretty big tooth profile. I think your teeth may be smaller than 12DP. The Logan QC I made gears for recently, had 20DP, 20 degree PA gears in it. The change gears on the end were 18DP. I have this 1880's Prentise Brothers lathe that has a few broken teeth in one of the back gears which is a fairly coarse tooth gear and it is a 14 DP.
I determined the DP size with a gear pitch gage.
I forgot to mention that I used an 8" rotary table mounted on edge of my Bridgeport. I placed a #3MT arbor in the center hole in the R-table and held it tight with a draw bolt. The arbor had a 1/2-20 thread extending from it. I stacked my gear blanks on it and tightened the nut on the end of the arbor to hold the blanks. I had no keyway to hold the blanks.
Charlie W.