On Tue, 27 Feb 2007 10:01:04 -0600, "Charlie M. 1958"
wrote:

Phil-in-MI wrote:
Just a guess on my part:

Portable tools need lightweight motors. The type of motor traditionally
used in circular saws is synchronized to the frequency of the prime AC
power. The only way to change the speed is to change the frequency from
60 Hz to say 40 Hz.

Hmmm... maybe that circular saw needs a VFD (variable frequency drive)
like the ones used in industrial applications. Wow, this saw is starting
to get pretty expensive now. g

VFD's are (albeit slowly) dropping in price, plus some of the newer designs are
starting to show up on the used market.

I think the continuing development of economical, highly integrated, solid
state high power devices in addition to be competitive innovations in vfd
designs that use fewer components overall are the factors currently driving the
prices lower.
regards, Joe

If/when the Chinese/India industries move into this market it will have a huge
effect in driving down prices, like in the MiG - tig- plasma cutter markets.
already.