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From: Bob Eld on 22 Mar 2010 10:33

"Terry Pinnell" <terrypinDELETE(a)THESEdial.pipex.com> wrote in message
news:or6eq5dq330c0j4q8vft3vtdfasp8njm7g(a)4ax.com...
> I made my Curtain Controller 6 years ago based on a motor I stripped from
an
> inexpensive battery-operated screwdriver drill (3V). In general it has
worked
> fine. But for the last year or two it has developed a strange intermittent
> fault. Suddenly, instead of opening or closing the bedroom curtains in
under
> 2 seconds, it will become glacially slow, taking maybe 10 seconds or so.
> Although it always gets there in the end (closing the appropriate
> microswitch), it's irritating.
>
> I don't mean 'intermittent' in the usual sense. It continues in this slow
> mode for several *months*. Then, just as suddenly, it will revert to its
> normal fast mode. And stay that way for months.
>
> A few days ago it once again reverted to slow mode, perhaps the 3rd or 4th
> time in 2 or 3 years. I made an even more concerted but fruitless effort
> than before to isolate the cause. It's definitely *not* the batteries, my
> primary suspect. I've tried several sets of 3 x NiCd/NiMh C-types,
> well-charged, all giving identical results. Voltage during operation
remains
> more than adequate for the 3V motor. I'm also sure it's not the mechanics,
> friction, obstruction, etc.
>
> Logically that seems to leave only the motor itself. Is it possible for
such
> a motor to exhibit this sort of behaviour and if so what's the likely
cause
> please? Is it fixable or am I going to have to find an identical motor?
>
> --
> Terry, East Grinstead, UK

Bad brushes and or dirty commutator is the most likely cause. Clean or
replace the brushes. If possible chuck up the motor rotor in a lathe and
lightly sand the commutator exposing fresh metal, blow clean. A three volt
motor has almost no voltage "head room" to allow for loses in the
brush-commutator junction. Dirt and bad contact can cause the loss of half
of the drive which is what you apparently experience. A higher voltage motor
is much less prone to such failures.


From: Terry Pinnell on 22 Mar 2010 13:35
"Bob Eld" <nsmontassoc(a)yahoo.com> wrote:

>
>"Terry Pinnell" <terrypinDELETE(a)THESEdial.pipex.com> wrote in message
>news:or6eq5dq330c0j4q8vft3vtdfasp8njm7g(a)4ax.com...
>> I made my Curtain Controller 6 years ago based on a motor I stripped from
>an
>> inexpensive battery-operated screwdriver drill (3V). In general it has
>worked
>> fine. But for the last year or two it has developed a strange intermittent
>> fault. Suddenly, instead of opening or closing the bedroom curtains in
>under
>> 2 seconds, it will become glacially slow, taking maybe 10 seconds or so.
>> Although it always gets there in the end (closing the appropriate
>> microswitch), it's irritating.
>>
>> I don't mean 'intermittent' in the usual sense. It continues in this slow
>> mode for several *months*. Then, just as suddenly, it will revert to its
>> normal fast mode. And stay that way for months.
>>
>> A few days ago it once again reverted to slow mode, perhaps the 3rd or 4th
>> time in 2 or 3 years. I made an even more concerted but fruitless effort
>> than before to isolate the cause. It's definitely *not* the batteries, my
>> primary suspect. I've tried several sets of 3 x NiCd/NiMh C-types,
>> well-charged, all giving identical results. Voltage during operation
>remains
>> more than adequate for the 3V motor. I'm also sure it's not the mechanics,
>> friction, obstruction, etc.
>>
>> Logically that seems to leave only the motor itself. Is it possible for
>such
>> a motor to exhibit this sort of behaviour and if so what's the likely
>cause
>> please? Is it fixable or am I going to have to find an identical motor?
>>
>> --
>> Terry, East Grinstead, UK
>
>Bad brushes and or dirty commutator is the most likely cause. Clean or
>replace the brushes. If possible chuck up the motor rotor in a lathe and
>lightly sand the commutator exposing fresh metal, blow clean. A three volt
>motor has almost no voltage "head room" to allow for loses in the
>brush-commutator junction. Dirt and bad contact can cause the loss of half
>of the drive which is what you apparently experience. A higher voltage motor
>is much less prone to such failures.
>

Thanks all, much appreciated.

--
Terry, East Grinstead, UK
From: tnom on 22 Mar 2010 16:09
>. I'm also sure it's not the mechanics,
>friction, obstruction, etc.

How about the mechanics of the motor assembly?
>
>Logically that seems to leave only the motor itself. Is it possible for such
>a motor to exhibit this sort of behaviour and if so what's the likely cause
>please? Is it fixable or am I going to have to find an identical motor?

Does the motor have gear pack reduction unit attached to it?
From: Baron on 22 Mar 2010 18:40
Terry Pinnell Inscribed thus:

> I made my Curtain Controller 6 years ago based on a motor I stripped
> from an inexpensive battery-operated screwdriver drill (3V). In
> general it has worked fine. But for the last year or two it has
> developed a strange intermittent fault. Suddenly, instead of opening
> or closing the bedroom curtains in under 2 seconds, it will become
> glacially slow, taking maybe 10 seconds or so. Although it always gets
> there in the end (closing the appropriate microswitch), it's
> irritating.
>
> I don't mean 'intermittent' in the usual sense. It continues in this
> slow mode for several *months*. Then, just as suddenly, it will revert
> to its normal fast mode. And stay that way for months.
>
> A few days ago it once again reverted to slow mode, perhaps the 3rd or
> 4th
> time in 2 or 3 years. I made an even more concerted but fruitless
> effort than before to isolate the cause. It's definitely *not* the
> batteries, my primary suspect. I've tried several sets of 3 x
> NiCd/NiMh C-types, well-charged, all giving identical results. Voltage
> during operation remains more than adequate for the 3V motor. I'm also
> sure it's not the mechanics, friction, obstruction, etc.
>
> Logically that seems to leave only the motor itself. Is it possible
> for such a motor to exhibit this sort of behaviour and if so what's
> the likely cause please? Is it fixable or am I going to have to find
> an identical motor?
>
> --
> Terry, East Grinstead, UK

Grease solidifying with age in the gearbox.

--
Best Regards:
Baron.
From: Kevin McMurtrie on 23 Mar 2010 01:10
In article <or6eq5dq330c0j4q8vft3vtdfasp8njm7g(a)4ax.com>,
Terry Pinnell <terrypinDELETE(a)THESEdial.pipex.com> wrote:

> I made my Curtain Controller 6 years ago based on a motor I stripped from an
> inexpensive battery-operated screwdriver drill (3V). In general it has worked
> fine. But for the last year or two it has developed a strange intermittent
> fault. Suddenly, instead of opening or closing the bedroom curtains in under
> 2 seconds, it will become glacially slow, taking maybe 10 seconds or so.
> Although it always gets there in the end (closing the appropriate
> microswitch), it's irritating.
>
> I don't mean 'intermittent' in the usual sense. It continues in this slow
> mode for several *months*. Then, just as suddenly, it will revert to its
> normal fast mode. And stay that way for months.
>
> A few days ago it once again reverted to slow mode, perhaps the 3rd or 4th
> time in 2 or 3 years. I made an even more concerted but fruitless effort
> than before to isolate the cause. It's definitely *not* the batteries, my
> primary suspect. I've tried several sets of 3 x NiCd/NiMh C-types,
> well-charged, all giving identical results. Voltage during operation remains
> more than adequate for the 3V motor. I'm also sure it's not the mechanics,
> friction, obstruction, etc.
>
> Logically that seems to leave only the motor itself. Is it possible for such
> a motor to exhibit this sort of behaviour and if so what's the likely cause
> please? Is it fixable or am I going to have to find an identical motor?
>
> --
> Terry, East Grinstead, UK

I'd guess that it got oiled too much. Oil on the electrical contacts
acts as a speed regulator by only allowing the brushes and commutator to
touch through the film when they move very slowly. The thicker the oil,
the slower the motor. You can probably clean it with a Q-Tip through a
vent hole. Luckily it's a 3V motor. A higher voltage motor would
quickly arc itself to death doing this.
--
I won't see Google Groups replies because I must filter them as spam
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