I saw a picture of marble machine years ago and I finally got around to trying to make my own. I seriously had doubts about getting it working; so I didn't want to invest money in nice wood. Therefore, besides the dowels, everything you see was made from a scrap 2x4.
As expected, it was a challenge to get mechanism worked out. I had to remake the cup and adjust the pivot point but I eventually got it working as shown in video.
The Amish seemed to have figured out this machine and get nice, smooth operation. You can purchase their Marble Roller Machine from Amazon. However, where's the fun in that? I will give a one year Instructuables premium membership to the first person that builds their own version (your plans or these) and post a picture.
Step 1: Tools/Materials
Step 2: Drawing
You will be building to this drawing. All parts are color coded for easy reference. There are many variables involved with this machine. With that in mind, I suggest reading all the steps before cutting any wood.
Step 3: Base
I shaved off the round ends of a 2x4 and then cut it down to the dimensions shown using a table saw. Drill the 5/8" holes 1" deep. Don't add the box hole (3" dimension) if you plan to use a bowl instead of a box.
Step 4: Track
Start by cutting down strips of 1" x 1.5" wood. These strips will be used for the vertical post and the two gussets.
The track is where you place the marbles. I used a router table to cut the slot. I then went back and drilled the 3/4" and 9/32" holes. The 10 degree angle on the end isn't needed but included it if you like.
Step 5: Post
Using one of the strips from the previous step, add the notch using a router table and a 3/4" bit. Drill the 1/4" hole per the drawing. The 10 degree angle on the end sets the slope of the track.
Step 6: Lever
Cut the 5/8" oak dowel to 17" long. Drill a 9/32" diameter hole 7" from one end. Note that you will want a tight fit between the pin and lever; so I wouldn't go any larger than 9/32". Tip: you might want to add 2" to the rod at this point to give you more options for adjustment later. If doing so, the dimensions from the pivot point should be 8" and 11".
Step 7: Counter Weight
This shape was arbitrary but I was able to get it from my 2x4. The cove cut along the edges is just me playing with the router - not necessary :). Drill the 5/8" hole through the center of the block.
Step 8: Cup & Incline
I had to build this part twice. The first version was only 1.5" wide (part of my strips). With those dimensions, sometimes the marbles wouldn't fall in the cup. The wider version along with rounded edges on the top works much better.
The incline is another addition (next step) that I think makes for smoother operation. I used a table saw with the blade set at 30 degrees to make this part.
Step 9: Cup Assy
Add the incline to the cup as shown. It will make sense once the machine is up and running.
Step 10: Gussets
These braces might not be needed but I was worried that the cantilevered machine didn't have enough support. I used a table saw with the blade set at the angles shown to make these parts.
Step 11: Stop Assy
Use a hole saw to cut the 2.5" circle. My saw had a 1/4" center bit so I didn't need to do anything else. Cut a 1/4" diameter dowel to 2.5" long. Insert the dowel into the circle - don't glue at this point.
Step 12: Dowels
You will need these dowels for the post and base. Make two of the 5/8" diameter pieces and one 1/4" piece.
Step 13: Box Parts
As you can see from my pictures, I didn't include a box to catch the marbles. I just used a glass bowl that fit nicely on the base. I had to add the tissue paper in the bottom after the family started complaining about the glass on glass noise. Anyway, it's your choice with regards to a bowl or building a box. If you go with the box, make two of each part.
Step 14: Assemble - Caution
This machine requires precision alignment. Therefore, I suggest doing a dry fit before gluing/screwing anything together.
Step 15: Assemble - Step 1
Using wood glue, add the 5/8 diameter dowels to the base as shown.
Step 16: Assemble - Step 2
Glue the post to the base as shown. Make sure the post is square to the base.
Step 17: Assemble - Step 3
Adding the track is tricky. Having an extra set a hands for this step would be useful. I used a wood screw and glue to make the connection. I'm not sure the gussets are needed but I feel like they make it more durable. This is especially true if you plan to give this machine to kids.
Step 18: Assemble - Step 4
I show this as Step 4 but you could interchange it with Step 3. Feed the lever through the slot. Add fender washers and push the 1/4" dowel through all parts. The dowel should be an interference fit - no glue needed.
Insert the stop assembly into the hole in the track. Although not shown in the drawings, adding an interference washer or spring pin (shown) under the stop assembly will limit the travel when hit by the cup. The version shown in the video doesn't include this pin.
Add the counter weight and cup (dry fit). When rotating the lever, the incline on the cup should hit the dowel on the stop assembly. You might need to adjust the cup out slightly to optimize the contact area. At this point, you will need to adjust the counter weight (move in or out) to get the correct movement. It took me about 5 minutes of trial and error to get this worked out.
Step 19: Assemble - Step 5
Glue the box together and place it on the base. Add marbles and you are ready to go.
Step 20: Pictures
Sand all the parts and clean up the joints. This version is stained in dark cherry.
Step 21: More Pictures
Step 22: Final Thoughts
Ok, I guess this is the time to fess up. It doesn't work as smoothly as shown in the video. Although I think it works pretty well, it took a few takes with the camera to get clean shots.
As you can see, there are multiple variables in play with this machine. I assume the Amish optimized it over time but my attention span is pretty short so you get what you get.
Here are the issues I encountered: The first was the marbles not releasing. This was fixed by adjusting the counter weight (moving it out) to provide more force. However, if you move it out too much, you will get too much force which will allow 2 marbles to fall out. I added the spring pin later which seemed to help. No pun intended but it really is a balancing act to fine tune this machine.
The other issue as mentioned earlier was the cup size. Although I made it larger, occasionally I get an errant ball that doesn't make it in. I think the main issue here is the slop at the pivot joint. I only had 1/2" diameter fender washers in my hardware bin. They also were not thick enough to fully cover the gap (3/4 - 5/8). I recommended 1" diameter washers in the instructions so hopefully that makes for a more controlled swing. Anyway, I'm pretty happy with how it turned out since my expectations were pretty low. If you have any suggestions on how to make it better, please let me know.
Thanks for viewing and happy building!