Links to stuff on this blog

Use the Site Index of Projects page link above for an easier way to find stuff on my blog that you might be looking for!

Sunday, April 11, 2010

Clock Movement with Pendulum Egg Looking Thing (Tamiya Gearbox)

I have made a little progress on the Steampunk looking digital alarm clock that I have been working on. This week (with what little time I have) I have focused on the clock movement. From the pictures in the last posts about this clock you can see the egg shaped spiral and the glass vase that I have been thinking about mounting on top of the clock. HERE is a picture of what I am talking about... This is going to sit on top of the clock and turn around providing some movement while the clock is keeping time. At one point I was considering not only having the egg spin inside the glass but change direction as well. So have it go one direction speeding up as it goes them slowly slow down to a stop and change direction going back the other way. Kind of like a pendulum in a real mechanical clock. To do that would have been a bit tricky and I decided that just having it turn is good enough.
To get it to spin I need of course a motor and some way to slow the motor down. The easiest way is with a gearbox on a motor. I have lots of gears around that I have taken out of various things like laser printers, clocks and other devices but to piece them all together would have been too big of a project. What I decided to do was buy a Tamiya Gearbox that you can get from a good hobby store. I have never used a Tamiya product so this is my first time messing with one. Tamiya makes all kinds of model cars and planes as well as educational robotic stuff. They have a line of just plain gearboxes for building your own stuff as well. Anyway here is the kit I got for a little over $10.00:

They call it the Tamiya Worm Gear Box H.E. (H.E. for High Efficiency). This comes with all the parts you need to put the gearbox together and some cool extra parts for attaching it to other stuff. They even include grease for the gears and an allen wrench for the set screws that they give you. You can get a couple of different gear ratios depending on how you put it together; 216:1 or 336:1. After putting it together the only negative comment I have about it is it is missing a shaft spacer for the output shaft. Without this spacer the last gear in the gear train can move on the output shaft and rub against the gear that is driving it. Maybe I put it together wrong or was missing a part but overall it is a cool little gearbox for a very good price.
Once I had the gearbox together I cut the threaded end off the egg shaped thing I have and drilled a hole in the center of the remaining shaft. Drilling a hole in the center of a shaft isn't all that easy but I managed to get it darn close to the center. I added some split toothpick wood strips as shims to get the egg right on center and will epoxy it once I'm happy with it.
I built the gearbox with the slowest ratio 336:1 and running on a 1.5 volt battery it turns a little faster than I like but it will be OK. The other thing that I decided to do was add a 'beauty ring' to the bottom of the glass bowl. This is one of those cast aluminum rings that you can get at the craft store that are intended for candles... I guess you put the ring at the base of the candle to make the base of the candle 'look beautiful'. I'm not so sure about that but I think it looks good at the base of the bowl. I'll probably paint it a different color before I mount it on the top of the box.
The last thing that I did was pick up an LED night light and take it apart. Inside there is a little PC board that has a light sensor and a high output LED soldered to it on long leads. I can extend the leads so the sensor pokes out a hole in the wood clock box and the LED points up into the glass bowl someplace near the base of the egg once it's installed in the bowl. I'm thinking about maybe getting some different colored pieces of plastic and attaching them to the gearbox along with the egg. That way as the egg turns inside the glass the LED will shine through the different colored plastic and change the color of the egg and bowl. I'll have to see how convenient that is as I get the top of the box constructed.

No comments:

Post a Comment