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“Focus on the journey, not the destination. Joy is found NOT in finishing an activity but in doing it.” - Greg Anderson

Building MORE Rolling Ball Clocks .

December-r-r-r 2019 - Work in progress....

Six more towers - 80% smaller. (actually 7 more when counting one 'oops')

Towers and tracks
Ball Clocks II & III

My original idea for building a Rolling Ball Clock was to make use of the old Bingo Balls from our Wednesday Bingo at Goodman Community Center. These balls are 7/8" (<23 mm) in diameter. After about a year in use, the numbers on these balls become unreadable and we order a new set. The balls are still fine and it's a shame to just throw them out so I thought this would be a nice use for them.

Now that I've built one clock (we'll call it full-sized) I feel comfortable adjusting the scale to 0.80 % and building another. And while I'm building another, why not build two.

I won't repeat the details for building these pieces except to talk about changes to either the technique or the design.

Here are the six towers and I'm beginning to attach the tracks.

Ball Tracks - Smaller size tracks and thinner wood.

ball tracks
Fixture for gluing ball tracks

All dimentions for these ball tracks were calculated at 80% of the first clock. This includes the measurements for the lengths and widths for all the pieces as well as the thickness of the wood.

I cut and glued it all together (including the making of new jigs and gluing fixtures).

I built this fixture to hold the tracks while gluing. This is necessary in order to keep the sides perfectly square with the bottom. When I just used clamps they tended to squeeze together on top.

The fixture is basically two 'L' shaped strips nested one on top of the other. The top strip is loosely screwed to the bottom strip. The holes for the screws are enlarged and the screws have fender washers and are tightened firmly but not tight, so the strip can slide with the clamps.

Ball Racks- will 80% size reduction work?.

ball racks
Ball racks for smaller balls

All dimentions for these ball racks were also 80% of the first clock. I cut and glued all the pieces -- this isn't easy to do with these angles.

... then I added the balls. The racks are too long! By about 2 balls. Now what?

I'll have to think about this while I work on the gears....

Changes in the way I make the gears.

wooden gears
Clock Gears with teeth and spacers

In the first clock, I made the gears by sequentuly gluing teeth and spacers around the circumfrence of the core disk. I used a printed template as a guide to keep a running track of the spacing so that I'd end up with equally spaced teeth all around the gear. This worked OK. But not great. The resulting gears meshed well over 90% of rotation. It quickly became obvious that this MUST be 100% for the clock to keep accurate time.

Therefore spacing is critical! Anyone who has made gears will say; "Duh".

If you Google "wooden gears", you will find many sites that discribe cutting gears out of plywood. There are template generators that will print out patterns. But I prefer the look of walnut teeth and oak spacers set in a plywood core and covered with hardwood facings.

 

Universal Dividing Head.

dividing head
Dividing Head

This Dividing Head is designed for making precision gears and is usually attached to a metal milling machine. It allows you to cut precisely spaced gear teeth in a metal disk (or blank). I will use it on wood.

 

Wooden Gear Making Fixture
Gear Cutting Fixture

Here is the Dividing Head mounted on a frame for cutting gear teeth slots equally spaced on a stack of 4 plywood disks, clamped together and chucked.

(click on picture to enlarge)

Wooden Gear Making Fixture
Four gear stack

I stacked 4 disks and clamped them together with a long 3/8" bolt. I chucked this into the Dividing Machine and made passes with a router to cut the grooves for the gear teeth. It took between 10 and 20 minutes to make all the grooves.

The proof of accuracy came if the last cut matched the first one exactly. I ended up repeating this on three sets of disks before I got it right. (third time's the charm).

(click on picture to enlarge)

disks
Finished disks

Cut strips of Black Walnut to the thickness of the grooves and a width slightly larger than the thickness of the disks.

Slice off tiles the desired length of the gear teath (figure in the depth of the groove and the thickness of the spacers to be added between teeth.)

 

(click on picture to enlarge)

Mounting Teeth
Adding teeth to gear

54 precicely cut Black Walnut gear teeth are glued and then tapped into the grooves of each gear.

(click on picture to enlarge)