I own a makita circular saw and it cuts very well and fast. was
however wondering if theres there a reason why circular saws are not
made with variable speed? It would be much more controllable i guess.

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.
These are cheap, loud, and powerful motors for the weight. Great for the
construction industry.

Modern batter power motors, modern motors that adjust speed by power voltage
and other factors (like not all who purchase circular saw are in the
construction trade or homeowner building a wooden deck,) maybe there might
be room in the market place for a high end saw with variable speed control.
Maybe even a circular saw that can be fitted into an accessory stand to
convert it into a cheap table saw. Sell the accessory stand for $72.97 and
the BORGs will sell lots of them. (Hey this is just a joke. Lighten up.)

I suspect the blade makers just might have some input into speed of the
blades with respect to teeth design.

Phil


"yuyu" wrote in message
s.com...
I own a makita circular saw and it cuts very well and fast. was
however wondering if theres there a reason why circular saws are not
made with variable speed? It would be much more controllable i guess.

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

On Feb 27, 9:59 am, "yuyu" wrote:
I own a makita circular saw and it cuts very well and fast. was
however wondering if theres there a reason why circular saws are not
made with variable speed? It would be much more controllable i guess.

no need for it
change blade parameters instead

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.

I own a makita circular saw and it cuts very well and fast. was
however wondering if theres there a reason why circular saws are not
made with variable speed? It would be much more controllable i guess.


I question that assumption. I don't believe slower RPM would give you
greater control. If you want the saw to cut slowly, push less. I would
immagine that really slow rpm would give you kickback rather than control.


Drills need variable RPM because they have variable diameter cutters
(various sized bits) as well as RPM-controlled self-feeding applications
(driving screws and auger bits come to mind).

Circular saws are (for the most part) fixed diameter and manually "fed".


-Steve



--
Posted via a free Usenet account from http://www.teranews.com

"yuyu" wrote in message
s.com...
I own a makita circular saw and it cuts very well and fast. was
however wondering if theres there a reason why circular saws are not
made with variable speed? It would be much more controllable i guess.


No, circle saw blades cut best at specific speeds, typically the speed that
your saw runs at.
I wonder however what control you want to improve?

On Feb 27, 9:59 am, "yuyu" wrote:
I own a makita circular saw and it cuts very well and fast. was
however wondering if theres there a reason why circular saws are not
made with variable speed? It would be much more controllable i guess.

Vary speed by varying the blade or the feed rate. Twice as many teeth
=
effectively twice the speed. Same with pushing the saw through the
board half as fast.

"Father Haskell" wrote in message
oups.com...
On Feb 27, 9:59 am, "yuyu" wrote:
I own a makita circular saw and it cuts very well and fast. was
however wondering if theres there a reason why circular saws are not
made with variable speed? It would be much more controllable i guess.

Vary speed by varying the blade or the feed rate. Twice as many teeth
=
effectively twice the speed. Same with pushing the saw through the
board half as fast.



A blade has an optimal cutting RPM. Feed in general rate does not change
that.

On Tue, 27 Feb 2007 15:36:30 GMT, "Phil-in-MI" NO Spam &
pam 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.
These are cheap, loud, and powerful motors for the weight. Great for the
construction industry.


You are describing an induction motor (synchronized to the frequency
of the prime AC), which delivers less power for its weight. Table
saws with belt drive typically use induction motors because weight is
not an issue and there is less maintenance (no brushes to replace).

Most portable power tools use some variation of what is usually called
a "universal" motor, which has brushes and a commutator. These motors
have a much better power-to-weight ratio than the induction motor.
The "universal" designation comes from the fact that many variations
can be run on AC or DC (not a major concern today, but was in the past
- DAGS on "death dealing AC" for some history)

John

On Feb 27, 1:57 pm, "Leon" wrote:
"Father Haskell" wrote in message

oups.com...

On Feb 27, 9:59 am, "yuyu" wrote:
I own a makita circular saw and it cuts very well and fast. was
however wondering if theres there a reason why circular saws are not
made with variable speed? It would be much more controllable i guess.

Vary speed by varying the blade or the feed rate. Twice as many teeth
=
effectively twice the speed. Same with pushing the saw through the
board half as fast.

A blade has an optimal cutting RPM. Feed in general rate does not change
that.

Right. But it does give you a surface twice as smooth with half the
resistance,
as if you had used a blade with twice as many teeth.

Leon wrote:

A blade has an optimal cutting RPM. Feed in general rate does not change
that.

You sure about that? I had always understood that tooth profiles were
designed with a specific amount of "bite" in mind, and that blade speed
and feed rate needed to be controlled together to get the best cut.

Thus, regular 10" blades are designed to work on standard saws at
"regular" feed rates. If you want to feed the stock faster (for
production use, say) then you need to use fewer teeth or a faster
rotation in order to clear the chips faster. However, if you feed too
slowly you can burn the stock due to the teeth spending too much time in
contact with the wood.

Chris

"Father Haskell" wrote in message
ups.com...


Right. But it does give you a surface twice as smooth with half the
resistance,
as if you had used a blade with twice as many teeth.



Correct, however that does not = more control.

"Chris Friesen" wrote in message
...
Leon wrote:

A blade has an optimal cutting RPM. Feed in general rate does not change
that.

You sure about that? I had always understood that tooth profiles were
designed with a specific amount of "bite" in mind, and that blade speed
and feed rate needed to be controlled together to get the best cut.

Blades are designed to cut best at a specific RPM. Best cutting does not
always = smooth.
Generally a slower feed rate produces a smoohter cut but may also introduce
a burned cut.


Thus, regular 10" blades are designed to work on standard saws at
"regular" feed rates. If you want to feed the stock faster (for
production use, say) then you need to use fewer teeth or a faster
rotation in order to clear the chips faster. However, if you feed too
slowly you can burn the stock due to the teeth spending too much time in
contact with the wood.

For optimum cutting with increased production you normally see a saw with a
larger diameter blade with more teeth than one of smaller diameter.

"yuyu" wrote in message
s.com...
I own a makita circular saw and it cuts very well and fast. was
however wondering if theres there a reason why circular saws are not
made with variable speed? It would be much more controllable i guess.


Maybe variable speed would work - at least in some conditions, but I could
see where stalls would be a huge problem for a saw. You can stall a
variable speed drill motor pretty easily, and a saw suffers some rougher
work than a drill does.

--

-Mike-

On Feb 27, 7:59 am, "yuyu" wrote:
I own a makita circular saw and it cuts very well and fast. was
however wondering if theres there a reason why circular saws are not
made with variable speed? It would be much more controllable i guess.

if you need more control, use a guide or push the saw slower. slowing
the motor RPM won't help.

slowing the rpm allow a slower feed without burning. just thought the
variable speed might be a good thing to have in a circular saw.

On Feb 27, 2:21 pm, "Leon" wrote:
"Father Haskell" wrote in message

ups.com...



Right. But it does give you a surface twice as smooth with half the
resistance,
as if you had used a blade with twice as many teeth.

Correct, however that does not = more control.

Control doesn't come from blade speed. Control comes with practice.

"Father Haskell" wrote in message
ups.com...
On Feb 27, 2:21 pm, "Leon" wrote:
"Father Haskell" wrote in message

ups.com...



Right. But it does give you a surface twice as smooth with half the
resistance,
as if you had used a blade with twice as many teeth.

Correct, however that does not = more control.

Control doesn't come from blade speed. Control comes with practice.


OK, perhaps you have missed the OP question. He wanted to know if he could
use a speed control to slow the motor down for more control. The correct
answer would be NO you cannot use a speed controller to slow down a circle
saw motor.

Feeding slower could give more control if feed rate is the problem. He did
not mention what kind of control problem he was having. There could be many
control problems that feed rate would not correct. Perhaps he is looking
for a soft start feature for better start up control. It is any ones guess.

In article m,
says...


I own a makita circular saw and it cuts very well and fast. was
however wondering if theres there a reason why circular saws are not
made with variable speed? It would be much more controllable i guess.


one of the best additions to my shop was the festool ts55eq. expensive,
but worth it.

take a look at:
http://www.festoolusa.com/ProductDet...&prodid=561174


--
regards,
greg (non-hyphenated american)
http://users.adelphia.net/~kimnach

Greg Kimnach wrote:

one of the best additions to my shop was the festool ts55eq. expensive,
but worth it.

take a look at:
http://www.festoolusa.com/ProductDet...&prodid=561174


Yup, Festool seems to be starting with a fresh piece of paper when
the design their versions of common handheld woodworking power
tools. Their plunge circular saw is a great example of what the
results of their approach produces - including variable speed.

The only other power tool brand that has done anything inovative
that I can think of is Dewalt with their DW621 plunge routers.
OK, so the sliding compound miter saw is another example- but
PowerMatic trumpeting their "inovation" of adding wheels to
a cabinet saw - well - DUH! My Robland X31 combi - which weighs
in at around 1,100 pounds - has a mobility kit as an option that
most buyers opt for. Most "euro" machines have a mobility kit
option - my LT16SEC bandsaw - which is "only" 385 pounds can
be moved around pretty easily when I need a longer infeed
outfeed alley. Otherwise, it's against the wall next to the
SCMS station.

I like to have options - and I'll pay more for them - if they
seem useful. Variable speed circular saws seem a useful
thing to have - when it comes to things to cut, one size
(fixed rpm, vary the number and type of teeth) does not
fit all cutting needs.

charlie b
tool phreak