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? > >JamieAn 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
How to slow down RPM of miter saw?
Started by ●November 29, 2014
Reply by ●December 2, 20142014-12-02
Reply by ●December 2, 20142014-12-02
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.
Reply by ●December 2, 20142014-12-02
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.
Reply by ●December 2, 20142014-12-02
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
Reply by ●December 2, 20142014-12-02
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. > EricThe 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
Reply by ●December 2, 20142014-12-02
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. > > JamieYes ! That is exactly what It is. :-) -- Best Regards: Baron.
Reply by ●December 3, 20142014-12-03
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 > > >JamieI 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
Reply by ●December 3, 20142014-12-03
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
Reply by ●December 3, 20142014-12-03
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. > > >JamieGreetings Jamie, I guess I did miss the point. Would you please explain it to me? Seriously. Thanks, Eric
