A Mini Tower Clock

[crueby]

'Time' for another project!   

This one will be a scaled down version of Wilding's tower clock. His original was large enough to drive a clock face up in the cupola above his workshop, mine will be large enough to drive a second dial up on the wall over the shelf. Its based loosely on his book, but the gear train has been reworked to be driven from a pair of off-the-shelf clock spring drums rather than the large weight of the original, a shorter pendulum with half-second vs one second tick, and can sit on a table top rather than its own floor frame. So, it will look basically the same from a distance but otherwise has been redesigned.

Tower clocks typically have much thicker gears and have a larger weight drive than a normal table or wall clock, since they have to be able to drive hands that can be several feet long, and withstand wind/rain/snow loads on those hands. Some tower clocks are wholey up in the tower, others like this one sit down at ground level with a drive shaft up to the dial in the tower. On this one, there is a dial and hands on the clock itself, though they are driven from the central gear itself, seperate from the ticking train. The hands on the main clock are in sync and move with the hands on the upper dial, and the minute hand on the main clock has a slip spring on its shaft to allow setting seperate from the ticking train on the other side. Here is what it will look like:

The upper dial may hang on the wall, or I may build a skeleton of a tower for it, undecided yet. As mentioned above, to replace the large weight of the original I have designed it for two winding drums on the same shaft (behind the lower blue gear in the drawing). I'll test with one, and add the second if its needed.

Also, note how the tower clock style has the main part of the gear train horizontal, suspended on individual posts. This let them adjust the mesh of the gears and also avoid one huge plate front and back for the gear trains. The final set of gears to the escapement are on a single bar set, those gears are the usual thin plate, 1/8" thick in this case vs the 1/4" thick of the rest of the gears. Its a very different look than the usual small movement with all the gears overlapping each other.

This is not the first clock I have built, but is the first of this style. Should be fun!

So far I have the plans generated from the CAD model - the main CAD work was done years ago, its finally made it to the top of my build list. Also, just finished cutting down the raw stock for the frame and the gears (LOTS of gears). Fortunately a bunch of years ago I bought a couple sheets of C353 Engravers Brass for the gears, the price on that stuff has skyrocketed in the last few years. The frame will be made from 360 brass bar stock, 1" square for the square sections on the vertical posts, with 3/4" round bar turned down for the rest of the posts. The horizontal frame bars will be 1/4" x 1" flat stock. Overall, the clock is 11" long.

Here is the 'kit' for the frame and gears. This set does not include the smaller pinion gears, which will be cut from regular round bar. The gears are all involute style, not the epicyclic gears of a normal house clock, and the one Kim is building. The shafts will ride in bearing bronze pivot bearings.

[cnr6400]

  Looks like a great project Chris! I'll bet the shop elves have the Mann truck raising steam and 124 wheelbarrows standing by for brass swarf removal. 

I'll send another 8 tons of the premium white popcorn kernels in the screamin Jimmy dump truck. The exhaust pipe is still broken, you'll probably hear it when it gets to Lewiston-ish. 

[crueby]

Looks like a great project Chris! I'll bet the shop elves have the Mann truck raising steam and 124 wheelbarrows standing by for brass swarf removal. 

I'll send another 8 tons of the premium white popcorn kernels in the screamin Jimmy dump truck. The exhaust pipe is still broken, you'll probably hear it when it gets to Lewiston-ish. 

The really fun part is when the elves get too close to the nozzle on the shop vac... Round and round inside the dust seperator!   
 

[wagnmkr]

This is going to be another very interesting build Chris. Looking forward to seeing it come to life.

Cheers 

[crueby]

This is going to be another very interesting build Chris. Looking forward to seeing it come to life.

Cheers 

[John MacArthur]

I love your work in general, but this one and Kim's really have my interest.
Johnny

[Sanjay F]

Wow - this is guna be a good'un 

[crueby]

Thanmks guys!   And for future fun based on this one, I'm thinking of adding a steam/air winding engine to wind it up (optional, still would have the normal key winder). Iniital thoughts were a v-twin joys valve engine, large bore, but two issues: 1, it would obstruct the view of the front of the clock, 2) did simulations on the Joy valve mechanism, and its a very touchy design to change dimensions on, decided that its not worth the risk. I may go with one of the set of slew/crowd engines also on my to-build-someday list. They are lower/more compact. A gear reduction to a chain drive would be needed. But, that can all be decided after the clock is ticking away...

[PJPickard]

To echo, love all your work but really looking forward to this one. I have Wilding's book and have thought about doing this exact thing!(not having a cupola for the dial!)

[crueby]

To echo, love all your work but really looking forward to this one. I have Wilding's book and have thought about doing this exact thing!(not having a cupola for the dial!)

Great to have you following along!  Since it was compiled from a lot of articles over years, the book can be a bit hard to follow and find things, but there is a lot of great info there.

[Kim]

You're projects are always fun, Chris, but I'm especially excited about this one! 

So, why are you going with involute gears rather than cycloidal?   
Inquiring minds and all...

Kim

[crueby]

You're projects are always fun, Chris, but I'm especially excited about this one! 

So, why are you going with involute gears rather than cycloidal?   
Inquiring minds and all...

Kim

Hi Kim,


Thanks for  looking in!


A number of reasons for the involute. I have the cutters.     I do have a home made cycloidal flycutter from my other clock builds though. Also I have seen  them used on other tower clock movements so there is precedent. Its easier to make pinions with larger tooth counts that I nedd, 20 on several of them. Also easier to make wide pinions, the gears on most of the train are 1/4" thick. The extra force available  means the efficiency is not  as important. The extra force means the wire for the cage type would have to be thicker, so more diameter, and the flycutter I have would not work. And I  feel like it! The last reason is the biggest!   


Chris

[Dave Otto]

This will be another fun one to watch!

Dave

[crueby]

This will be another fun one to watch!

Dave

Hopefully it has a nice tickover from the exhaust!  Um... Wait...   


 

[wagnmkr]

I  spent hours watching the steam powered clock in Vancouver when I lived there. It added another dimension.

 

Tom