Intermatic Timer Pinon Gear

[John Keiser]

I see replacement pinon gears in common Intermatic lamp timers was
discussed in 2005. A more current model [TN711] and drive motor [WG2030]
uses a pinon gear that has readily crumbled [in the heat and humidity of
Hawaii, anyway]. The remnants are a golden, waxy color.
Poor quality nylon?
The gear train is hard plastic. The gear train works fine.
My question, for curiosity's sake, is why would the pinon gear be made of
such soft/poor/fragile material?

[Jeff Liebermann]

Let me guess... you're using it to run a swimming pool chlorination
system? Of course, I discovered this that hard way. Nylon is
destroyed by strong aqueous chlorine compounds.
See chemical compatibility charts at:
<http://www.plasticsintl.com/plastics_chemical_resistence_chart.html>

Another possibility is LOW humidity, as in a refrigerator. When Nylon
6/6 is molded, it is stiff, hard, and brittle. In order to give it
some flexibility and resiliance, it is given a water bath. Nylon is
hydroscopic and typically absorbes about 3% moisture by weight. If
you dry nylon out with a combination of cold and low humidity, it
reverts back to its native stiff and brittle state and crumbles.

--
Jeff Liebermann je...@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

[Cydrome Leader]

Jeff Liebermann <je...@cruzio.com> wrote:
> On Sun, 21 Sep 2014 15:49:56 -1000, "John Keiser"
> <john.k...@hawaiiantel.net> wrote:
>
>>I see replacement pinon gears in common Intermatic lamp timers was
>>discussed in 2005. A more current model [TN711] and drive motor [WG2030]
>>uses a pinon gear that has readily crumbled [in the heat and humidity of
>>Hawaii, anyway]. The remnants are a golden, waxy color.
>>Poor quality nylon?
>>The gear train is hard plastic. The gear train works fine.
>>My question, for curiosity's sake, is why would the pinon gear be made of
>>such soft/poor/fragile material?
>
> Let me guess... you're using it to run a swimming pool chlorination
> system? Of course, I discovered this that hard way. Nylon is
> destroyed by strong aqueous chlorine compounds.
> See chemical compatibility charts at:
> <http://www.plasticsintl.com/plastics_chemical_resistence_chart.html>
>
> Another possibility is LOW humidity, as in a refrigerator. When Nylon
> 6/6 is molded, it is stiff, hard, and brittle. In order to give it
> some flexibility and resiliance, it is given a water bath. Nylon is
> hydroscopic and typically absorbes about 3% moisture by weight. If
> you dry nylon out with a combination of cold and low humidity, it
> reverts back to its native stiff and brittle state and crumbles.

Might just be cheap trash plastic. The smallest spinning gear is also
going to get the most wear. The oddest problem I ran into with intermatic
timing motor modules was demagnetized magnets, making them too weak to
start up most of the time. I still haven't figured out how to cross
reference those things into something you can still buy even though it
looks like they still make them. The circa 1980s ones had molded
pinion/magnet assemblies made of some type of hard black plastic.

[John Keiser]

Good guess Jeff, but no, used to time lamps in the house while on vacation.
Not near the swimming pool and not in a refrigerator. I have several timers
and I noticed that at least 2 have stopped turning. Disassembly of one
revealed the rotted pinon gear in an otherwise virginal looking timer. Your
explanation seems to rule out Hawaii's high humidity as a cause. Perhaps
"just" age.
Any clever idea as to what design criteria dictated use of this grade nylon?



"Cydrome Leader" <pres...@MUNGEpanix.com> wrote in message
news:lvoar6$1mu$2...@reader1.panix.com...

[Jeff Liebermann]

On Mon, 22 Sep 2014 04:01:33 -1000, "John Keiser"
<john.k...@hawaiiantel.net> wrote:

>Any clever idea as to what design criteria dictated use of this grade nylon?

Lowest bid supplier?

Supposedly, Nylon tends to yellow with age but not lose any of its
strength. Indoor use and being inside a box eliminates UV exposure
and dehydration as possible culprits. Another bad guess(tm) might be
that the Nylon was attacked by solvents in the lubricating grease, but
it's difficult to imagine that the little grease inside the timer
would do much damage. Nylon can be depolymerized with steam in the
presence of assorted catalysts (used in recycling plastics), but
that's also unlikely. Yellowing in Nylon can be caused by UV
exposure, which is also unlikely.

Lacking any additional forms of attack, I think we can safely default
to the Nylon having been improperly prepared or molded, and having
destroyed itself. In other words, I have no idea exactly what
happened.

No recall notices on the TN711:
<http://www.intermatic.com/en/CustomerSupport/ProductRecalls.aspx>
You might be able to get a replacement timer by contacting Intermatic,
but methinks a digital timer might be a better replacement.

Useless, but interesting items found while Googling:

Method for restoring whiteness to yellowed nylon fabrics
<http://www.google.com/patents/US2830868>

Retr0bright (which doesn't work on nylon but works well with ABS):
<http://retr0bright.wikispaces.com/>

[John Keiser]

Thank you Jeff.
Oh, I have ample replacements from garage sales. I did contact Intermatic
only to complain. The nylon was mush - way beyond restoring. :)


"Jeff Liebermann" <je...@cruzio.com> wrote in message
news:cge02alsqm94gvvfg...@4ax.com...

[Arfa Daily]

"Jeff Liebermann" <je...@cruzio.com> wrote in message

news:ld4v1a1cdlpj4aon8...@4ax.com...

> On Sun, 21 Sep 2014 15:49:56 -1000, "John Keiser"
> <john.k...@hawaiiantel.net> wrote:
>
>>I see replacement pinon gears in common Intermatic lamp timers was
>>discussed in 2005. A more current model [TN711] and drive motor [WG2030]
>>uses a pinon gear that has readily crumbled [in the heat and humidity of
>>Hawaii, anyway]. The remnants are a golden, waxy color.
>>Poor quality nylon?
>>The gear train is hard plastic. The gear train works fine.
>>My question, for curiosity's sake, is why would the pinon gear be made of
>>such soft/poor/fragile material?
>
> Let me guess... you're using it to run a swimming pool chlorination
> system? Of course, I discovered this that hard way. Nylon is
> destroyed by strong aqueous chlorine compounds.
> See chemical compatibility charts at:
> <http://www.plasticsintl.com/plastics_chemical_resistence_chart.html>
>
> Another possibility is LOW humidity, as in a refrigerator. When Nylon
> 6/6 is molded, it is stiff, hard, and brittle. In order to give it
> some flexibility and resiliance, it is given a water bath. Nylon is
> hydroscopic

That's hy - g - roscopic, Jeff ... d;-)

Arfa

[Jeff Liebermann]

On Tue, 23 Sep 2014 01:19:45 +0100, "Arfa Daily"
<arfa....@ntlworld.com> wrote:

>That's hy - g - roscopic, Jeff ... d;-)
>Arfa

<http://www.answers.com/Q/What_is_the_difference_between_hydroscopic_and_hygroscopic>
I stand correctified.

[Arfa Daily]

"Jeff Liebermann" <je...@cruzio.com> wrote in message

news:e8h12apjk9dhft6v8...@4ax.com...

> On Tue, 23 Sep 2014 01:19:45 +0100, "Arfa Daily"
> <arfa....@ntlworld.com> wrote:
>
>>That's hy - g - roscopic, Jeff ... d;-)
>>Arfa
>
> <http://www.answers.com/Q/What_is_the_difference_between_hydroscopic_and_hygroscopic>
> I stand correctified.

No problem, sir !

Arfa

[Samuel M. Goldwasser]

Yeah, the $6 timer only lasts about 15 years. ;-)

But I agree it's annoying. All the other gears are brass and don't
wear.

Does anyone know of a replacement source other than to cannibalize other
timers?

--- sam

[mrob...@att.net]

Samuel M. Goldwasser <s...@repairfaq.org> wrote:

> "John Keiser" <john.k...@hawaiiantel.net> writes:
>
>> A more current model [TN711] and drive motor [WG2030] uses a pinon
>> gear that has readily crumbled [in the heat and humidity of Hawaii,
>> anyway]. The remnants are a golden, waxy color.

I wonder if the switch contacts generate enough ozone to do anything to
the nylon?

> But I agree it's annoying. All the other gears are brass and don't
> wear.

Maybe that one crummy gear is a "fuse" for the drive train? I have a '64
VW that has one fiber gear in the wiper motor gearbox, while the rest are
metal; I suspect it might be there in case the wipers are frozen in place
by ice.

Matt Roberds

[John Keiser]

Intermatics response:
"The TN711 has been discontinued and replaced with the TN311 which is known
for it's durability."




"Samuel M. Goldwasser" <s...@repairfaq.org> wrote in message
news:874mvy6...@repairfaq.org...

[Samuel M. Goldwasser]

I don't think so because installing a replacement from another motor
will get you another 15 years. :)

--- sam

[John Keiser]

I think the wife bought a 4 pack at Costco since I seem to have 4 of these
and they are all bad!


"John Keiser" <john.k...@hawaiiantel.net> wrote in message
news:x5adnbuxI-Q7o77J...@powerusenet.com...