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More from the Treenut woodpile ....

Begin building a Rolling Ball Clock.

January 2018 - Work in progress....

I've always wanted to build a Rube Goldberg sort of thing and a rolling ball clock has always seemed to fill that bill -- in my mind.

Ball Clock patent
Figure of US Patent 4,077,198
(click on image to enlarge)

Okay, there are tons of of these things out there. All different designs and sizes and shapes. Just Google "Rolling Ball Clocks" to get an idea.

I've been searching for these on the INTERNET for years and all I got was offers for kits. This fall I found the first place that offered plans for building one of my own that were reasonably priced.

I ordered a complete set of plans for only $25.00. I downloaded them (as PDF) and printed them out. They are great. Very well thought out and complete.

Here is their web site if you'd like to order your own copy:


These folks are very responsive and have kindly answered all the questions I have emailed to them.

With plans in hand I set about to build this rolling ball clock.

My first thought was that this project would be a great way to use up some of the small pieces of scrap wood that I've accumulated over the years from building other projects. Then I decided that this clock would look great with a mixture of Red Oak and Black Walnut (my favorite combination) but I don't have many scrap pieces of Black Walnut.

What I did have was a nice pile of Black Walnut that I'd cut for firewood last winter and stacked in my back yard.

Trim the pieces with a hatchet and then square up piece on table saw (I don't have a band saw). Shave off nice pieces of Walnut for splines and for ball track sections.

Wood Pile Trimming Walnut Sawing Walnut log
Black Walnut source
Walnut boards
Ball Tracks

Track Pieces

Strips of Walnut sliced from billet in 10 mm width for track sections and 2mm width for splines.

Track sections

Rough track stock glued and sanded. I decided to round-over one edge, both bottom and top, to dress up the track a bit. I left the side that attaches to the towers square for maximum glue surface.

Red Oak used for towers

The track support towers are made from Red Oak and fashioned from rough cut pieces of wood that originated in family woodlots in north-west Wisconsin.

The plans called for just butting these pieces together and gluing. I made splines out of the black walnut. Splines will add a little strength and give it a nice look.

It took a bit to figure out how to spline a corner joint. I ended up cutting the spline material into a triangle. Each such spline would join one upright with two 'arms'.

Make sure the grain in the spline goes parallel to the base and that the base goes into the upright. This puts the strength of the spline grain perpendicular with each arm.

Corner view spline
Tower Splines

Attaching Track

tracks Corner
Corner Corner
building Track Corners

Track Corners

I changed up the corner sections a bit from the plans. The intent was to make them match the track in size so that it followed smoothly around the corner. Using a combination of Red Oak and Black Walnut just continues the theme.

Corner Corner
Corner Corner
building Track Corners

Corner sections are cut on a 4 1/4" hole saw (this cuts a radius of 50mm plus a saw curfs). This produces a half circle in White Oak that will be glued to a base of Black Walnut. These are glued and stacked together for clamping.

When the glue sets these pieces are cut in half, trimmed and sanded. The top and bottom are routed with a 3/16" round-over and then the 'inside' edges of each corner piece is trimmed to match the space it will fill. These are roughly 50mm but there are small variations.

Corner Corner
Corner Corner
building Track Corners (19 plus a few 'spares')
Problem: stuck ball

While trimming each corner piece to fit the tracks, I was paying too much attention to making a smooth connection to the outside of the tracks (for a clean look) and I forgot to watch the inside (ball track) as I was slicing off bits of stock. This caused the inside track to squeeze the trail so the ball would catch on the edge.

Lucky i noticed this during the pre-glue clamping. (Lucky I'd decided to order the balls before the rails were done.

So three of my nice corner pieces were suddenly scrap. Or maybe not ...


Cut through track section challenge

cut through
track merge (finished)

This bit is a little tricky. I couldn't tell from the pictures and plans whether this diagonal track joins the side track or just overlays it and drops the ball in from above.

I emailed the authors and they said it did merge and applogized that it wasn't clearer in the plans.

I held off on gluing the target track in place until I knew where to cut the notch.

measure angle for drop

1.Measure drop angle:

All the track sections on this tower drop at 7-degrees each. This diagonal will have to be steeper in order to join the target track. Clamp a straight-edge in the position of the merge track and lay a piece of track stock in position between it and the 45-degree angle piece. Then measure this angle (20-degrees).

Cut the top edge of the diagonal track piece.

layup for merge

2. Mark compound angle for merge cut:

With top angle cut, position diagonal on straight-edge and mark bottom to get first angle.

Carefully hold the track in position and project a vertical cut up the side of the track section from the outside edge of the straight-edge to find the second angle. (a second pair of hands would have been helpful).

Set up the saw and cut this compound mitre cut. (of course the first try came up a little short so I had to make a secornd piece. this time I started with the compound end and then slowly shaved off the top a little at a time until it fit.)

3. Cut out notch in long track section:

mark cut saw limits chisel out finished
Cut out slot for merge track
glue in
layup for merge

4. Glue in place:

I'll leave it to you as to how you want to glue and clamp this piece in place.

There's another of these merges in towrer #2 so I'll tackle that while this is fresh in my mind.

stay tuned....

winter scene
it's cold out there

If it seems to you like this project is taking a long time to build, it seems that way to me too.

But I live in Wisconsin and my workshop is in my unheated garage . When my fingers get numb, I quit for the day.

Time Racks

ball rack
cut pieces for racks

These three 'teater-totter' track pieces are where the balls line up to show the time. Thes are a little trickier to make because of the expansion at one end.

Many places in these plans, I found it helpful to draw a full scale picture of the piece and then work from that.

ball rack
ready to glue

I'll put up pictures of the completed racks tomorrow....

Begin to apply finish

ball rack
Apply Polyurethane

The first tower (right) has all the tracks attached so it's time to put on the first coat of finish.

I use a cloth instead of a brush because of all the nooks and crannies that can catch the liquid and cause running and droops and other problems.

See the finisned racks on the right.

ball rack

See how the finish brings out the color of the wood. Unfinished tower in foreground.