Wooden percussion elements

Rocker element

The rocker element is a sort of see-saw that throws marbles up in the air.

Marbles are dropped on the left side of the rocker element. The marble then rolls to the right side. When the next marble is dropped on the left side, the impact catapults the marble on the right side off the rocker.

The main part of the body of the rocker element is glued together out of three pieces of wood.

It's easiest to trim the pieces to their final length after gluing them together. This ensures the ends of the pieces are all flush.

Next, two smaller pieces are glued to the rocker. The grain orientation of these pieces is parallel to that of the main block, so the pieces are actually cut across the grain.

The corners of the rocker base are cut round with a bandsaw, then sanded.

The shape of the rocker paddle is cut off the edge of a piece of wood on the bandsaw, using a paper template.

The rocker paddle is screwed loosely into the base. The piece should be able to tip towards the right side a bit, but not too far to the left. If it can tilt too far to the left, marbles might not roll to the right. Note that the slope of the floor of the machine puts the whole element at an incline, so marbles will roll to the right even if the rocking piece is level with the top or inclined slightly to the left.

The arrows show the path of marbles in the rocker. The marble at the end of the up arrow really bounced that high.

Clacking box

The clacking box is designed to make a loud clack when a marble falls onto it.

The base of this box is hollow. It's cut out as two halves, so the inside can be cut with a bandsaw. A scroll saw would be too slow in thick hardwood.

There's a slot in the side of the box to let the sound out, although I'm not sure it makes much of a difference. I'm drilling a series of 1/2" holes to shape the slot...

... then chiseling out the sides.

Now gluing the halves together. I smoothed the bandsaw-cut joint surfaces with a belt sander. Also note that I haven't cut the pieces to length yet. I trim the length after gluing the halves together. That makes sure both pieces are flush with each other, just like I did with the rocker element (sorry, I neglected to take a photo of that step)

The clacking box is just slightly higher where the top attaches. So to cut the rest of it lower, I'm passing it over the table saw. I didn't bother to peel off the template because this step cuts away most of it.

Although I used a paper template for the top, it's actually easier to cut it on the table saw than the bandsaw. The paper template is still useful to make sure I have the size right, and for cutting the corner radiuses on the bandsaw afterwards.

Now screwing the lid on the box. The screws aren't tightened all the way down, so the top can vibrate freely.

Doing a quick sound check of the clacking box, comparing it to the one for my first marble machine 2. I originally cut the top to be 5 mm thick, but the sound wasn't as good as the old one, so I cut it down to 3 mm. I changed the plans to 3 mm.

Next: Xyloboard and alignment pegs

Back to Marble machine 2.1