24th-Apr-20, 08:56 AM
(28th-Mar-20, 05:28 AM)slotloco Wrote: The dirty fix, I like that term. But I think you are confusing the outside diameter of the gear with the pitch circle diameter.
I believe the basis of this is changing the pitch circle diameter, to keep the effective pitch of the pinion as a differing circle diameter as close to the 0.5 modulus mid point as possible.
If for instance I swapped a Slot.it 6.5mm 10 tooth sidewinder pinion for a 12 tooth, the contact point of the 12 tooth, would be further out from the centre of the motor shaft, and the pitch wouldn't change by x 12 ÷10.
Have a look at the different tooth shapes here, and how you might expect the two pinions to contact at a different pitch circle diameter point with a straight toothed spur gear
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So the "pitch" or modulus value doesn't change as much as we would assume it does.
Does that all, those both make sense?
Loco
Re-reading the thread, this item caught my eye again... I'm struggling to see how the profile of the teeth will effect the pitch of the gear.
Are you suggesting that the 'virtual' diameter of the 10t gear is smaller than the actual diameter because the other gear will mesh with it at the fatter lower part of the tooth rather than towards the outer tip?
I love puttering with gears