Egg on face time. There is indeed an offset on the WOSP motor. Near enough
4mm - which would give the gear more clearance than the difference between the two pinions which are 25mm and 29mm diameter, not radius.Just as well I didn't go ahead and buy the later pinion for the old PowerLite.
Thanks for bouncing things around chaps. Pushing me in the correct direction. To understand it.
sounds good then, also if your 25mm and 29mm were measured between gear tips, the effective diameter would be less, since it should be measured [more or less midway] between tip and root ... the "module" of the gears should be compatible if the teeth/effective diameter of the two are the same.
Sounds to me like the gear has a module of 2. So, from the standard calculations the 9 tooth gear would have pitch diameter of 18 mm and tip diameter of 22. 11 tooth gear would have pitch diameter of 22 mm and tip diameter of 26 mm. Your pinions are 21 and 25 mm OD, so perhaps there is a little tip relief to help them cope with debris. The pitch radius only differs by 2 mm so you would need an offset of 2 mm to change the pinion safely. Your offset of 4 mm sounds like more than is needed. But, involute gears are relatively insensitive to the centres distance. It's only insufficient clearance that will destroy gears quickly, not excess.
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