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Originally Posted by Richard
1/64" ~= 0.0156" and 3/2 x 1/64 ~= 0.0234" so by your rule-of-thumb sanddrag has enough thickness (0.028") below the root diameter above the keyway.
Still it seems thin to me. I would not want to shock load it.
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You are right, my mistake -- I am mildly dislexic 1/16 and 1/64 seem occupy the same spot in my head. At times I am sure that 1/16 is ~0.064 (right) and at others I am sure that it is ~0.016(wrong). The fate of 1/64 is equally confusing to me. Sometimes it comes out ~0.016 (right) sometimes it comes out ~0.064 (wrong).
In any case, I am just flat out wrong on this one on at least 2 accounts. First because I mixed up the decimal version of 1/64. Second because the formula for tooth thickness was just wrong.
Let me see...
Allow me to point out my mistake:
Pitch Diameter is Nteeth / DP
Distance around Pitch Circle is Pitch Diameter X Pi = Nteeth X Pi / DP
Tooth Thickness is Distance around Pitch Circle/ (2 X Nteeth)
= (Nteeth X Pi / DP) / (2 X Nteeth) = Pi / (2 X DP)
So...
I was off by a factor of Pi in my formula.
For 32 DP, the circular tooth thickness is then:
Pi/64 = .048"
.028 is STILL too thin for my rule of thumb but my initial answer was right for the wrong reasons.
Joe J.