On Wed, 3 Dec 2014 17:00:30 -0500, "Maynard A. Philbrook Jr."
<jamie_ka1lpa@charter.net> wrote:

>In article <n2nu7aljnn5728uo23vupuleuhrb3r19a8@4ax.com>, 
>etpm@whidbey.com says...
>> > 
>> >  You can dynamically brake a series motor but it's not as simple as 
>> >just connecting the A1 and A2 together.
>> >
>> >Jamie
>> >
>> >
>> >Jamie
>> I know it is not that simple. Please follow the link or just search
>> for the patent number. It describes a system that supplies the DC.
>> Eric
>> 
>> 
>
>I guess you missed the point, oh well.
>
>
>Jamie
Greetings Jamie,
I guess I did miss the point. Would you please explain it to me?
Seriously.
Thanks,
Eric

In article <n2nu7aljnn5728uo23vupuleuhrb3r19a8@4ax.com>, 
etpm@whidbey.com says...
> > 
> >  You can dynamically brake a series motor but it's not as simple as 
> >just connecting the A1 and A2 together.
> >
> >Jamie
> >
> >
> >Jamie
> I know it is not that simple. Please follow the link or just search
> for the patent number. It describes a system that supplies the DC.
> Eric
> 
> 

I guess you missed the point, oh well.


Jamie

On Tue, 2 Dec 2014 16:22:14 -0500, "Maynard A. Philbrook Jr."
<jamie_ka1lpa@charter.net> wrote:

>In article <bh3s7ah06br8cdtal7q8dmuggna2rchq16@4ax.com>, 
>etpm@whidbey.com says...
>> 
>> On Mon, 1 Dec 2014 21:06:34 -0500, "Maynard A. Philbrook Jr."
>> <jamie_ka1lpa@charter.net> wrote:
>> 
>> >In article <enip7a17pheiant16dhullsb1hma9us1mq@4ax.com>, 
>> >etpm@whidbey.com says...
>> >> 
>> >> On Sat, 29 Nov 2014 19:18:57 +0000, Baron <baron@linuxmaniac.net>
>> >> wrote:
>> >> 
>> >> >John Doe prodded the keyboard
>> >> >
>> >> >> The motor runs on standard USA 120 V 60 Hz, 14 A, at 5500 RPM.
>> >> >> 
>> >> >> What's the easiest way to slow down the RPM?
>> >> >> 
>> >> >> What about simply adding a diode in series on the power cord?
>> >> >> 
>> >> >> Any advice, references, and links would be appreciated.
>> >> >> 
>> >> >> Thanks.
>> >> >
>> >> >This would depend upon the type of motor !  If we assume a universal
>> >> >motor then a thyristor or triac phase controler that can handle the
>> >> >maximum current plus 100% could be used.  An induction motor would
>> >> >need a variac (variable transformer) or one of the electronic devices
>> >> >used specifically for this purpose.  But I would doubt that what you
>> >> >have uses an induction motor.
>> >> Every power miter saw I have seen in the last 25 years had a universal
>> >> motor. They also have a circuit that dynamically brakes the motor when
>> >> the trigger is released. I wonder if that circuit would have any
>> >> negative effect on certain speed controllers. Probably not. In any
>> >> case universal motors have poor speed regulation. And lowering the
>> >> voltage or current significantly my make the speed regulation really
>> >> bad. As I recall from reading about it this is partly because the
>> >> brushes are located in the best place for the least amount of sparking
>> >> and changing the voltage or current will change this location.
>> >> Eric
>> >
>> > It would be interesting to how a series motor can be dynamically braked
>> >in a hand tool?
>> >
>> >Jamie
>> An induction motor can be dynamically braked by connecting DC to the
>> windings. This can be done with a capacitor and a diode. I think that
>> if the brushes are shorted and DC is connected to the windings this
>> would work like an induction motor. See this link:
>> http://www.google.com/patents/US3548276
>> It is from 1970.
>> Eric
>
> The key is DC current... where does one get that from a device that 
>only has an off/on switch to a series motor with no magnets for self
>generation?
> 
>  You can dynamically brake a series motor but it's not as simple as 
>just connecting the A1 and A2 together.
>
>Jamie
>
>
>Jamie
I know it is not that simple. Please follow the link or just search
for the patent number. It describes a system that supplies the DC.
Eric

Maynard A. Philbrook Jr. prodded the keyboard

>> Have a look at the "SawTech" Italian machines.  Mine is a direct
>> drive 2Hp single phase induction motor running at 2800 rpm with a
>> 10" blade.  There is no gearbox !
> 
> Sure, you have 50Hz with a 2 pole (Tree Rat) cage motor and ~6%
> slip.
> 
> Jamie

Yes ! That is exactly what It is. :-)

-- 
Best Regards:
                       Baron.

In article <bh3s7ah06br8cdtal7q8dmuggna2rchq16@4ax.com>, 
etpm@whidbey.com says...
> 
> On Mon, 1 Dec 2014 21:06:34 -0500, "Maynard A. Philbrook Jr."
> <jamie_ka1lpa@charter.net> wrote:
> 
> >In article <enip7a17pheiant16dhullsb1hma9us1mq@4ax.com>, 
> >etpm@whidbey.com says...
> >> 
> >> On Sat, 29 Nov 2014 19:18:57 +0000, Baron <baron@linuxmaniac.net>
> >> wrote:
> >> 
> >> >John Doe prodded the keyboard
> >> >
> >> >> The motor runs on standard USA 120 V 60 Hz, 14 A, at 5500 RPM.
> >> >> 
> >> >> What's the easiest way to slow down the RPM?
> >> >> 
> >> >> What about simply adding a diode in series on the power cord?
> >> >> 
> >> >> Any advice, references, and links would be appreciated.
> >> >> 
> >> >> Thanks.
> >> >
> >> >This would depend upon the type of motor !  If we assume a universal
> >> >motor then a thyristor or triac phase controler that can handle the
> >> >maximum current plus 100% could be used.  An induction motor would
> >> >need a variac (variable transformer) or one of the electronic devices
> >> >used specifically for this purpose.  But I would doubt that what you
> >> >have uses an induction motor.
> >> Every power miter saw I have seen in the last 25 years had a universal
> >> motor. They also have a circuit that dynamically brakes the motor when
> >> the trigger is released. I wonder if that circuit would have any
> >> negative effect on certain speed controllers. Probably not. In any
> >> case universal motors have poor speed regulation. And lowering the
> >> voltage or current significantly my make the speed regulation really
> >> bad. As I recall from reading about it this is partly because the
> >> brushes are located in the best place for the least amount of sparking
> >> and changing the voltage or current will change this location.
> >> Eric
> >
> > It would be interesting to how a series motor can be dynamically braked
> >in a hand tool?
> >
> >Jamie
> An induction motor can be dynamically braked by connecting DC to the
> windings. This can be done with a capacitor and a diode. I think that
> if the brushes are shorted and DC is connected to the windings this
> would work like an induction motor. See this link:
> http://www.google.com/patents/US3548276
> It is from 1970.
> Eric

 The key is DC current... where does one get that from a device that 
only has an off/on switch to a series motor with no magnets for self
generation?
 
  You can dynamically brake a series motor but it's not as simple as 
just connecting the A1 and A2 together.

Jamie


Jamie

In article <m5l800$o6d$1@dont-email.me>, baron@linuxmaniac.net says...
> 
> Tom Biasi prodded the keyboard
> 
> > On 12/2/2014 12:23 AM, Jasen Betts wrote:
> >> On 2014-12-01, Tom Biasi <tombiasi@optonline.net> wrote:
> >>>
> >>>>>
> >>>> I used to repair such and I have never seen one that directly
> >>>> drove the blade, they all had reduction gears.
> >>>
> >>>
> http://www.bing.com/images/search?q=direct+drive+saws&qpvt=direct+drive+saws&FORM=IGRE
> >>
> >> Many of those images are clearly gear driven saws.
> >>
> > I can't help that. Many are not. The statement was "I have never
> > seen one that directly drove the
> > blade"
> 
> Have a look at the "SawTech" Italian machines.  Mine is a direct drive
> 2Hp single phase induction motor running at 2800 rpm with a 10"
> blade.  There is no gearbox !

Sure, you have 50Hz with a 2 pole (Tree Rat) cage motor and ~6% slip.

Jamie

On 12/2/2014 3:38 PM, Baron wrote:
> Tom Biasi prodded the keyboard
>
>> On 12/2/2014 12:23 AM, Jasen Betts wrote:
>>> On 2014-12-01, Tom Biasi <tombiasi@optonline.net> wrote:
>>>>
>>>>>>
>>>>> I used to repair such and I have never seen one that directly
>>>>> drove the blade, they all had reduction gears.
>>>>
>>>>
> http://www.bing.com/images/search?q=direct+drive+saws&qpvt=direct+drive+saws&FORM=IGRE
>>>
>>> Many of those images are clearly gear driven saws.
>>>
>> I can't help that. Many are not. The statement was "I have never
>> seen one that directly drove the
>> blade"
>
> Have a look at the "SawTech" Italian machines.  Mine is a direct drive
> 2Hp single phase induction motor running at 2800 rpm with a 10"
> blade.  There is no gearbox !
>
>
None of my saws have a gear box.

Tom Biasi prodded the keyboard

> On 12/2/2014 12:23 AM, Jasen Betts wrote:
>> On 2014-12-01, Tom Biasi <tombiasi@optonline.net> wrote:
>>>
>>>>>
>>>> I used to repair such and I have never seen one that directly
>>>> drove the blade, they all had reduction gears.
>>>
>>>
http://www.bing.com/images/search?q=direct+drive+saws&qpvt=direct+drive+saws&FORM=IGRE
>>
>> Many of those images are clearly gear driven saws.
>>
> I can't help that. Many are not. The statement was "I have never
> seen one that directly drove the
> blade"

Have a look at the "SawTech" Italian machines.  Mine is a direct drive
2Hp single phase induction motor running at 2800 rpm with a 10"
blade.  There is no gearbox !


-- 
Best Regards:
                       Baron.

On Mon, 1 Dec 2014 21:06:34 -0500, "Maynard A. Philbrook Jr."
<jamie_ka1lpa@charter.net> wrote:

>In article <enip7a17pheiant16dhullsb1hma9us1mq@4ax.com>, 
>etpm@whidbey.com says...
>> 
>> On Sat, 29 Nov 2014 19:18:57 +0000, Baron <baron@linuxmaniac.net>
>> wrote:
>> 
>> >John Doe prodded the keyboard
>> >
>> >> The motor runs on standard USA 120 V 60 Hz, 14 A, at 5500 RPM.
>> >> 
>> >> What's the easiest way to slow down the RPM?
>> >> 
>> >> What about simply adding a diode in series on the power cord?
>> >> 
>> >> Any advice, references, and links would be appreciated.
>> >> 
>> >> Thanks.
>> >
>> >This would depend upon the type of motor !  If we assume a universal
>> >motor then a thyristor or triac phase controler that can handle the
>> >maximum current plus 100% could be used.  An induction motor would
>> >need a variac (variable transformer) or one of the electronic devices
>> >used specifically for this purpose.  But I would doubt that what you
>> >have uses an induction motor.
>> Every power miter saw I have seen in the last 25 years had a universal
>> motor. They also have a circuit that dynamically brakes the motor when
>> the trigger is released. I wonder if that circuit would have any
>> negative effect on certain speed controllers. Probably not. In any
>> case universal motors have poor speed regulation. And lowering the
>> voltage or current significantly my make the speed regulation really
>> bad. As I recall from reading about it this is partly because the
>> brushes are located in the best place for the least amount of sparking
>> and changing the voltage or current will change this location.
>> Eric
>
> It would be interesting to how a series motor can be dynamically braked
>in a hand tool?
>
>Jamie
An induction motor can be dynamically braked by connecting DC to the
windings. This can be done with a capacitor and a diode. I think that
if the brushes are shorted and DC is connected to the windings this
would work like an induction motor. See this link:
http://www.google.com/patents/US3548276
It is from 1970.
Eric

John Doe <always.look@message.header> wrote in news:m5d282$si5$1@dont-
email.me:

> The motor runs on standard USA 120 V 60 Hz, 14 A, at 5500 RPM. 
> 
> What's the easiest way to slow down the RPM? 
> 
> What about simply adding a diode in series on the power cord? 
> 
> Any advice, references, and links would be appreciated. 
> 
> Thanks.
> 


I missed a part of the discussion due to the limitations of my news servers 
so I may tell no news. Nevertheless:

This type of machines usually have universal motors. They can be slowed 
down by ordinary dimmer like controllers. This however is not very 
effective as lowering the voltage will make the speed very dependend of the 
load. The best way to control this type of motors is using DC and PWM.

In my experience Al will not be cut very effective by an abrassive disk. 
The soft Al will smooth the disk by filling the spaces in it. I got the 
best results using a saw blade with hardened steel teeth as for hardwood,

petrus bitbyter