On Fri, 02 Oct 2020 00:23:35 +0100, T i m wrote:

There are formulae for the right speed for cutting all sorts of
materials, with and without lube and so to answer that we may need to
know the thickness of the steel and the pitch of the blade (which I
think ideally needs to be 'matched' (or within certain criteria)).

Ideally I think you need at least three teeth to be within the
thickness of the material being cut at all times. This prevents the
material dropping deeper between the teeth as it moves along the
blade, thus giving each tooth more to cut than it should have.
Remember you can increase the "thickness" by cutting at a shallow
angle.

Rate of cutting and speed of blade is "common sense" coupled with
"let the tool do the work". Broadly the soft/ductile materials
(acrylic, aluminium, lead) cut best at low speeds. Harder ones faster
but brittleness come into it as well...

--
Cheers
Dave.