gearcutter
Industrial
I need to cut some helicals to an old British system; "Sykes". The specs call for 4 DP "Real", 15 deg Helix angle, 20 deg Pressure angle. This works out to 4.141 Normal DP. As there is no chance of getting hold of a hob to do this I'm thinking of roughing out with a 6 module 20 deg hob and finishing the blanks on a gear grinder. The question I have is; Is the Pressure angle for this system in the normal or transverse plane? The drawing doesn't specify which. I'm assuming it's in the tranverse plane but thought I'd better check. Does any one know where I can get more information?