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Wood Marble Loop

When I made the worm gear brass marble lifting project, I failed miserably at making a marble track from 2 wires, including a vertical loop.  I gave up on the wire track and went with a wood marble tower instead.

I got to wondering, could I make a vertical loop from wood instead of 2 wires??

My idea was to make the loop in quarter sections.........then successively rotate each segment about 11 degrees so when the 2 curved tracks meet.........they don't interfere with each other.

Making the Quarter Segments

This was straightforward, as expected.  I printed out the curved piece in Sketchup, then used it to scroll saw out the segments.

I then used hot melt glue to attach them as I built clock-wise from the entry piece.

I designed the entry point to align with a straight ramp set at 20 degrees from the vertical.  I can always adjust this angle based upon testing.

After I got the main track base done, I installed 3/16" Luan pieces on the inside and outside of track, then sanded the outside diameters.  The inner guide is shared between the inner and outer loop.


When I did the first set of tests, I did not realize the loop was not rotationally in its correct position, with a 20 degree entry angle.  After I caught it, I corrected it for the 2nd set of tests.

17 inches was the minimum height I got on the first set of tests, which is a ratio of 17 divided by (4 inch diameter divided by 2 for radius =2) which equaled 8.5 ratio.

Then I studied the loop inside tracks and guides on sides and saw some rough spots, so I dremel sanded all inside areas.

After sanding, I got the minimum height down to 14 inches for a ratio of 14/2 = 7.0..........twice what the guy said 3.5 in the real world.

An  Existing Marble Ramp

I searched the internet to find anyone else that might have built a wood marble loop. Initially I could find nobody, probably because it is hard to make.

Then I found a 20+ series of Youtube videos on the Mini Golf Marble Machine, you can use this link to see the wood loop part.

He is using standard 5/8" marble size, not the 1 inch I am using.

On his mini golf project, he only has 5.5 inches of drop height to work with. He is aware of the theoretical 2.5 ratio of drop height to loop radius. He decides to use a diameter of 2.25 inches, which gives a ratio of 5.5 to (half of 2.25 for radius) = 4.90.

My best ratio using a 4 inch loop with 1 inch marbles was 7.0

He used a different approach to building his loop than I did.  He made his loop in just 3 pieces, where I used 5 pieces. He shared the inner track guide rail between the inner and out loop like I did. He used solid wood for the guide pieces instead of Luan like I did, so his sanded loop had better look than mine.  His shared piece is only 1/8" thick while mine is 3/16".

I wonder why he achieves a much better drop height to loop radius ratio than I do??

His chute angle looks like maybe 30 degrees and my design is 20.   I think 20 is too steep after testing, the marble slips instead of rotating down the chute.

May 7, 2021

Had an idea to try, maybe my chute is not aligned with my spiral roughly 11 degrees spiral.

I went back to test rig, and was surprised I could operate at the 12 inch mark, which at a 40 deg ramp angle is really 9 inches  !!!!!!!!!!!!

It did not matter which angle my chute was in and out of the test rig.

So that means my best ratio is 9 inches divided by 2 inch radius = 4.5 !!!!!!!!!!!!      I am beating the Youtube guy's ratio of 4.90 now !!!!!!!!!!!

WOW !!!!!!!!!!

Maybe I should fill my wood loop with wood filler, and paint it, and fix a piece of chute to it solidly.  I should also maybe grind a horizontal flat on the bottom to mount it, plus keep the entry angle at the right place.

Other thoughts:

1. Can I add this chute to my brass marble model?

2. Should I try making a 3" diameter wood loop using the Youtube guy's method of making it in 3 pieces instead of 5?   and use
    pine instead of Luan for the guides so it sands and blends better?

Trouble drawing Loop in sketchup

I have drawn springs and worm gears in sketchup, so I did not think a marble loop would be a problem.

When I used the spring drawing method, which includes the follow me command, the floor of the track rotated as it went around the loop, and was not horizontal after 1 and time for exiting of the marble.

More Googling

Found Youtube video showing how to make a spiral marble ramp, which is really a different version of a vertical loop. You can use this link to watch that video.

The youtube guy made 1 mistake, he forgot to say you need to hold down the Alt key when you move the cross section of the ramp up. It doesn't work unless you do this.  Discovered this in the Comments section of that video.

Success !!!!!!!!!!!

I got the 4 inch OD vertical marble loop draw in Sketchup !!!!!!!!

I used a 30 degree from horizontal entry angle for the chute to come in.

The wall between the halves of the loop is duplicated in sketchup. It can be built this way, or you can just just one shared guide.

Getting Loop ready to paint