The Dale C. Maley Family Web Site

I recently bought a multiple fall marble game with 6 falls of the marbles. 



I decided to build some variants of this design which add bell ringing to the game.

Marble Path

On previous marble games, I have made the marble track several ways. One way Is to use a 3/4" diameter ball nose router bit, in 3/4" thick wood. The marbles I use are 5/8" diameter, so the marble will ride in a 3/4" groove, as long as the track is a straight line.

If you want a curved marble track, the ball nose router bit option won't work, because you can not route a curve with this bit.

So,  how do you route a marble track on a curved piece?  You need a router bit with a guide bearing. I went to the MLCS web site, and searched their bits.  The best option I could find was this bit.

 


I ordered the 1/2" flute diameter set Item #315.

In theory, you make the 1st cut on the router table like this......

The reason for 2 passes is that a 1/2" wide groove is not wide enough for a 5/8" diameter marble.

Here is the 2nd cut:

There is a small raised ridge in the bottom of the groove, but this does not bother marble motion at all.


Actual Router Bit Cuts

In this case, the theory shown above pretty much matches my actual results on a test piece......

On the marble game I bought, the groove depth is closer to 3/8" versus the 1/4" depth achieved by my router bit set-up.

If I went to a smaller diameter guide bearing, I could cut deeper.

I went back to the MLCS web site, and ordered a ball bearing guide #266. It will allow the bit to cut deeper and match the original model I bought. 

Wal-Mart Bell

About the only bell I can find and verify the dimensions are from Wal-Mart for about $5 each.  You can find bells online, but almost all of them give no dimensions for the bell.



Sketchup Design without Bell

Here is the design without the bell.......

 1-1/4 Router bit for Big Groove in Top Piece

I went back to the MLCS web site and bought Dish Cutter #7815 1-1/4" diam.  It should route the big groove in the top. 

 1st Rest Run of making a curved Track

I glued up some common pine to make the 1st test piece.  I also made a pattern using 1/2" thick plywood.  I marked the pine from the pattern, then band-sawed about 1/8" outside of the pencil lines.  This leaves enough stock to route to the pattern.

I was going to use double-sided tape to attach the blank to the pattern, but I had trouble with my old roll of tape, and the piece of plywood I chose is not perfectly flat.  I ended up using 3 dabs of hot-melt glue to temporarily attach the blank to the pattern.  I was able to remove the hot melt with a chisel when done.

The flush routing went fine on the router table........




Routing the 1st groove in a Curved piece of Track

I decided to rout the groove in 2 passes, meaning I started with the bigger OD bearing on the 1st pass, then switched to the smaller OD bearing for the final pass.

This worked well, except I accidentally touched the piece to the router bit when I was moving it between cuts, and put a little ding in the track.  I need to remember to be careful when I make the real tracks!!







Except for the handling ding, I was very happy with the process I  used to make the first curved piece.  I got very little burning of the wood, which might have been helped by doing 2 versus 1 pass on the groove.  I should do 2 passes when I make more curved track pieces.

First Top Piece with 1-1/4" diameter groove

I drilled the 3/4" hole first before taking the piece to the router table.

When I started to feed the piece left-to-right on the router table, the bit kicked the piece out a little, which means the resultant groove will not be straight.

The lesson learned from this test piece is to clamp a temporarily fence on the router table to keep the board from kicking out like this one did, not a big deal.  I had a little wood burning. I did this groove 1/4" deep on 1 pass, maybe I should try 2 passes and see if I guess less burning.  If I do 2 passes, then I need a stop block on the end with the hole, so both passes start the same place.

Now that I have the tooling and process developed, I can crank out the pieces needed for several marble games.

I should also develop and assembly jig to quickly locate all the pieces at final assembly. Maybe a piece of plywood with dowels to locate all of the key pieces.

Making 4 Grooved Top Pieces

I set-up the router table to route the big groove in 2 passes.

I got a little bit of wood burn on the poplar at both ends of the groove.......... 

I used my 15 gage air nailer to nail 1.5" long finish nails from the curved track to the 2 vertical 3/4 by 3/4" verticals. You have to pay attention and not put the nail in the upper part of the curved track, or you will go through the routed track (I did this once  ). I yellow-glued the joints also.

I could also stand up this assembly jig as I went, and test how the marbles ran ......to make sure everything was ok.

Then I just Titebond yellow glued the last 2 verticals to the assembly with no nails.

Bell

I had to do some trial & error work to find the best spot to locate the Wal-Mart bell. I then used 2 screws from below the box to go up and hold the 2.25" diameter round poplar disc the bell was attached to.

1st Finished Multiple Fall Marble Game with Bell

YouTube Video

I made a YouTube video showing the 1st completed marble game in action.

 YouTube Video

Closing Thoughts

It took some process development work to figure out how to route the marble groove in a curved track, but we figured it out.

The only process that did not work well was flush router trimming the curved track to final size.  Chunks of wood blew out on the big curved end.  I should probably scroll saw these in the future, or possibly put the smallest size blade I have in my big band-saw and try that.

The 1st curved track is a little slow acting, and I checked the lower angle.  It is only about 0.5 degrees, and the rest of the tracks are 1 to 2 degrees as-built.  I should test this on the next units I build as I assemble them.







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