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From: Ron Hubbard on 20 Feb 2010 04:17 I was doing some carpentry work in my bedroom with a belt sander and in one careless moment, I put the tool down on a blanket as the motor was winding down. Less than 30 seconds later, part of the blanket has gotten caught up in the gears. It's been a long while since I've built a motor controller. Does anyone know of a circuit-- preferably a really simple one-- for reversing an AC motor? I hate to have to buy a new sander, and I miss my blanky... <g> Ron
From: Jasen Betts on 20 Feb 2010 04:58 On 2010-02-20, Ron Hubbard <ryon(a)dslnorthwest.net> wrote: > I was doing some carpentry work in my bedroom with a belt sander and > in one careless moment, I put the tool down on a blanket as the motor > was winding down. Less than 30 seconds later, part of the blanket has > gotten caught up in the gears. > > It's been a long while since I've built a motor controller. Does > anyone know of a circuit-- preferably a really simple one-- for > reversing an AC motor? I hate to have to buy a new sander, and I miss > my blanky... <g> open up the motor and swap the connections to the brushes. If the terminals to do that aren't provided externally it can't be done from outside the motor. www.howeverythingworks.org/supplements/electric_motors.pdf unbiversal motors paragraph 3. reversing the brushes has the exact (opposite) effect of reversing the stator wiring, (and so has the same result) but is generally easier to do --- news://freenews.netfront.net/ - complaints: news(a)netfront.net ---
From: Ron Hubbard on 20 Feb 2010 19:16 Jasen Betts wrote: > On 2010-02-20, Ron Hubbard <ryon(a)dslnorthwest.net> wrote: > > I was doing some carpentry work in my bedroom with a belt sander and > > in one careless moment, I put the tool down on a blanket as the motor > > was winding down. Less than 30 seconds later, part of the blanket has > > gotten caught up in the gears. > > > > It's been a long while since I've built a motor controller. Does > > anyone know of a circuit-- preferably a really simple one-- for > > reversing an AC motor? I hate to have to buy a new sander, and I miss > > my blanky... <g> > > open up the motor and swap the connections to the brushes. > > If the terminals to do that aren't provided externally it > can't be done from outside the motor. > > > www.howeverythingworks.org/supplements/electric_motors.pdf > unbiversal motors paragraph 3. > > reversing the brushes has the exact (opposite) effect of reversing the stator > wiring, (and so has the same result) but is generally easier to do. Hey, great. This info is much appreciated! Now if I can only get it open... what did I do with that hammer and chisel, hmm? <g> Ron
From: Jasen Betts on 20 Feb 2010 23:43 On 2010-02-21, Ron Hubbard <ryon(a)dslnorthwest.net> wrote: > > > Jasen Betts wrote: >> On 2010-02-20, Ron Hubbard <ryon(a)dslnorthwest.net> wrote: >> > I was doing some carpentry work in my bedroom with a belt sander and >> > in one careless moment, I put the tool down on a blanket as the motor >> > was winding down. Less than 30 seconds later, part of the blanket has >> > gotten caught up in the gears. >> > >> > It's been a long while since I've built a motor controller. Does >> > anyone know of a circuit-- preferably a really simple one-- for >> > reversing an AC motor? I hate to have to buy a new sander, and I miss >> > my blanky... <g> >> >> open up the motor and swap the connections to the brushes. >> >> If the terminals to do that aren't provided externally it >> can't be done from outside the motor. >> >> >> www.howeverythingworks.org/supplements/electric_motors.pdf >> unbiversal motors paragraph 3. >> >> reversing the brushes has the exact (opposite) effect of reversing the stator >> wiring, (and so has the same result) but is generally easier to do. > > Hey, great. This info is much appreciated! Now if I can only get it > open... what did I do with that hammer and chisel, hmm? <g> if it were my sander I'd be looking for a way to dissasemble it unless the brushes can be accessed without dissasembly (some tools provide ports for replaceing the brushes without opening the "shell" but even then rigging it with the wires crossed could be a little tricky another option may be finding a hole you can insert a probe into to push the rotor round, and winding it back by hand. --- news://freenews.netfront.net/ - complaints: news(a)netfront.net ---
From: Ron Hubbard on 21 Feb 2010 01:21
Jasen Betts wrote: > On 2010-02-21, Ron Hubbard <ryon(a)dslnorthwest.net> wrote: > > > > > > Jasen Betts wrote: > >> On 2010-02-20, Ron Hubbard <ryon(a)dslnorthwest.net> wrote: > >> > I was doing some carpentry work in my bedroom with a belt sander and > >> > in one careless moment, I put the tool down on a blanket as the motor > >> > was winding down. Less than 30 seconds later, part of the blanket has > >> > gotten caught up in the gears. > >> > > >> > It's been a long while since I've built a motor controller. Does > >> > anyone know of a circuit-- preferably a really simple one-- for > >> > reversing an AC motor? I hate to have to buy a new sander, and I miss > >> > my blanky... <g> > >> > >> open up the motor and swap the connections to the brushes. > >> > >> If the terminals to do that aren't provided externally it > >> can't be done from outside the motor. > >> > >> > >> www.howeverythingworks.org/supplements/electric_motors.pdf > >> unbiversal motors paragraph 3. > >> > >> reversing the brushes has the exact (opposite) effect of reversing the stator > >> wiring, (and so has the same result) but is generally easier to do. > > > > Hey, great. This info is much appreciated! Now if I can only get it > > open... what did I do with that hammer and chisel, hmm? <g> > > if it were my sander I'd be looking for a way to dissasemble it > unless the brushes can be accessed without dissasembly (some tools > provide ports for replaceing the brushes without opening the "shell" > but even then rigging it with the wires crossed could be a little tricky > > another option may be finding a hole you can insert a probe into to > push the rotor round, and winding it back by hand. I was just joking-- mostly. Ryobi is a very under-rated company. They make very rugged tools and it took me nearly an hour to find all of the screws (hidden and otherwise) holding the sander together. But once done, it didn't take very long to fix the problem although re- assembly was a little trickier as some of the screws are shorter than others, going into specific places rather than a single size screw that can go in anywhere. Ron |