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wrote:
Thanks for your reply Grunff. For interest though my maths for the
above is as follows.

Circumference = PI * diameter

so for the 160 diameter trend, we get

3.142 * 160mm = 502.72 mm for the circumference.

Now there are 48 teeth around the circumference so

48/502.72 = 0.09548 teeth per centimetre.

To get this number of teeth per centimetre on a 300 mm diameter blade,
we would need a blade of

300mm * PI * 0.095 = 90

So a 90 tooth 300mm blade would have the same number of teeth every
centimetre as a 48 tooth 160mm blade.

Now my maths may be flawed, but could you expand a little on where I
am going wrong.

cm != mm

You make the error twice and it cancels out, leaving sensible results, but
the main teeth/cm figure is actually teeth/mm.