have you the time?

A fun project to do when you need a clock to run backwards.

Saturday, March 25, 2006

 


This is a travel clock that you can set an alarm. In my experience with 3 or 4 different clocks with similar mechanisms the plate can be reversed to make the clock run counter-clockwise.





I use the scissors to place the clock shaft in the middle so it doesn't press on the gears while I work. The first thing is to get the back off of the clock to expose the gears. A small standard screwdriver is a good choice. Don't forget to take the small black knobs off the time adjustment wheel. If you don't they will shoot off as you pry the back cover of the clock.



Study the way this looks and remove parts slowly as you learn. The left most gear is minutes, the middle is seconds and the right and smallest gear below work together to calculate the second hand movement. The smallest gear turn approximately 180 degrees each second. Unfortunately, it is complicated to watch the clock with the cover removed as it requires an alignment hole to be in place on the cover side.



The gears simply pull straight up and out and you can set them down in order as you go. The focus is on the orientation of the plate inside the copper wound electromagnet. As you work the plate up and off of the pins that hold it in place, take care not to pull at the copper wound mechanism. The plate should slide out of a plastic rectangle slot, the copper is not wrapped around the plate itself.





This is the original orientation of the plate.



Some plates can be pulled out, flipped 180 degrees and be replaced, done. When it doesn't work like that, I nip off about 3/32 at a 45 degree angle as shown.



As you can see the plate is restored and it fits over the guide pins.



Take care when replacing the cover that the smallest gear is pointing straight up as much as possible to align it for the cover. When the cover is replaced it won't smash the shaft. If the shaft gets smashed they might weaken too much to be straightened again. During this mod one of the wires came off underneath the copper winding and the clock wouldn't work, so I soldered and reassembled.

Comments:
how does simply flipping the plate over make the clock run backwards? It looks as though its orientation doesn't matter, like a wire or resistor...
 
the plate is magnetic i think so it changes the polarity
 
I think it's cool. You can print out reverse clock numbers. Instead of 11 being to the left of 12, it would be 1, then 10 would be 2, than 9 would be 3. It would still be accurate, just backwards. If you print the numbers backwards you can put it in the bathroom and the clock would appear correct in a mirror.

Totally kewl!
 
goldscott/stephen:

I was wondering the EXACT same thing. For one the plate shouldn't be magnetic since the coil is(or should be) getting an A/C voltage and that would tend to demagnetize the plate.

At first I thought that the coil was being put on the other "leg" of the plate while still maintaining the orientation which might make some sense but at this point I'm going to have to experiment with some of the clock movements I have laying around here at the house.
 
The mechanics in my clock are almost exactly the same...layout etc, I'd just like to say that mine worked perfectly...good tutorial, I'm gonna need a mirror now tho :P
 
mine works perfectly as well. and i tested it, and that metal pin is in fact magnetic.
 
This comment has been removed by a blog administrator.
 
Thanks, Moddy! I just finished this mod on a Mainstays brand (Walmart) clock. My plate had two holes on the long side that aligned with plastic nubs. I used nail clippers to snip the nubs.

I'm giving it as a gift later today. Fun!
 
FWIW the small tiny cog that sits in the gap between the two plate "arms" contains a magnet, hence once battery power is applied to the electro magnet there results in two opposite magnetic poles, forcing each other away, only thing is one magnet is stationary (electro magnet) the other magnet is contained in a cog, forcing it to turn as poles pass the opposing magnet
 
Nice hack.
Is that just a clock or an alarm clock?

If you set the alarm to 12 and set the clock to 10, you would have a 10 hour kitchen timer.
 
Wow nice indeed!
I also had problems with the copper of the coil, very easy to pull out, but I've been able to solder it back, now clockwise is no longer clockwise :D
 
it's working!!...TQ....i've done two my clock....huhuhuh..

it's funy N make somebody confiuse....

we can go to yesterday...huhuhuhu
 
great idea... i was searching for the same... any way thanks to u....
 
Why nipping off a small piece at the corner would do the trick? what's the physics behind that?
 
When the magnet was manufactured, it was made in a way that it could only be put on with the correct polarity. If the magnet is symetrical, all that is required is to flip it. If it is an odd shape, snipping the corner off (in this case) allowed the magnet to be placed with the opposite polarity and run backwards with perfect time.
 
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