"The Medway Handyman" wrote in
message m...
I've often said that Makita stuff seems to punch above its weight.
I've got a 860w Makita router that performs better than a 1200w 'shed'
own brand, a 950w circular saw that eats 38mm worktop & a 14.4v combi
that I reckon would see off a lot of 18v tools.

I wonder if this is down to the way they quote the figures.

snip

I do have some sympathy for the power tool makers here, and not just
because I worked for one many years ago.

Take a simple tool like a mains-powered drill. What matters about its
power? Is it the maximum power it can deliver at the chuck, running
continuously - which is how you might rate an electric motor used on a
production lathe? Or is it the maximum power you can use in short
bursts, as in, say, drilling a succession of large holes in masonry? If
so, do you assume the drill runs on no-load for a while between holes,
enabling the fan to cool it, or that it's left stationary between holes?
Is it always the maximum power that's important, or the maximum torque?
And what happens if the torque-speed curve is such that it falls away so
rapidly with decreasing speed that the drill stalls easily?

This is looking at it purely from the electrical point of view. What
about the effect on mechanical components of running at maximum output?
A pair of gears might transmit a relatively huge amount of power for a
couple of minutes occasionally, which might be what matters when you
encounter a re-bar in your lintel, but how do you take into account that
their life under these conditions will be short? Six-tooth pinions are
fine at 1 rpm in a longcase clock, heaving a seconds-hand round, but
drill makers routinely use them at 30000rpm on the end of armatures.

So, in the end, it's a matter of judgement: the manufacturers' and the
users', and I really don't think that a single figure, or a set of
figures, or even a couple of graphs, is going to help anyone a great
deal. So we'll carry on as we do now: marketing departments will insist
on quoting implausible and meaningless numbers, and we'll carry on
buying on the basis of hearsay, budget, and prejudice (or accumulated
wisdom, as some prefer to call it). Oh, and engineering judgement - but
not fancy colours or go-faster stripes.


--
Kevin Poole
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