A simplified way to build the marble pump
When I first built this marble pump, I milled it out of a solid block of maple using my slot mortiser. But I wanted to make a set of plans available for this marble block set, so I needed to find a way to build it using more commonly available machines. I'm just using a table saw, drill press and bandsaw to build this marble pump. I also used a 11/16" (or about 17 mm) drill bit.
I'm using the templates from the marble block plans
The outside layers have two small holes, and one side only has a 11/16" hole. I used an awl to pre-punch the hole-centers through the paper template to make sure I got the positions just right. Alignment is critical.
I recommend using a closed grain hardwood, such as maple, birch, cherry or mahogany. Avoid woods with strong ring patterns such as oak or ash or hickory, as the grain may pull the drill off to the side a bit.
There is also a notch that needs to be cut off one end. The templates are very handy for avoiding measuring errors. When I built my earlier version, that notch tripped me up because I got mixed up measuring to the notch vs. to the end of the piece of wood.
The levers placed roughly where they will end up. Note that they overlap with the middle layer. That's because the part of the middle layer between the red lines will get drilled away in a later step. I left this part solid because it makes it easier to align and easier to drill out later.
Note the three lines going across the middle layer. These are slight indentations marked on the middle layer templates. I cut a slight notch where each of these is to mark where holes need to be drilled later.
Leaving this slight bridge prevents chipout as the hole is drilled and also prevents the drill from wandering to the side. If you are using one of those dreadful spade bits, you may want to make the middle layer a bit wider on that side because spade bits are very messy at drilling.
The holes for the nails should be just larger than the nails but smaller than the heads. That way, when the nails are driven in flush, the head will get stuck in the holes, holding them in place.
For countries with sensible (not fractional) systems of measurement, the holes for the alignment pegs should be 0.5 to 1 mm smaller than the holes at the bottom of the blocks.
Cutting dowel pieces to go in the holes. 15/64" is an odd size. Dowels at hardware stores are often very inaccurate, so you may be able to find one just that size. Or you can make any size dowel using this method. This dowel actually was made using a half round router bit. It was one of my slightly misshapen earlier experiments, so I just sanded it round on the belt sander.
I chamfer one end of the buttons on the belt sander. This would be easier to do with the whole dowel, before cutting pieces off, but that would mean going back and forth between the belt sander and the bandsaw.
Testing the pump with a ramp. The marble won't quite roll in, so I need to carve out the hole, slightly cone shaped, towards the top. I'm also widening it towards the sides a bit, just in case the input ramp is slightly misaligned to the side.
Another rubber band is used to force the small lever on the other side, which prevents the marbles from falling back down when the lever is released. That lever drops down by gravity, but not reliably so.
Making the top marble releaseMaking this part is not as tricky as making the marble pump, but I did rely on my horizontal boring machine to drill the 45-degree hole. A drill press may not have sufficient rigidity to start that hole on an outside corner.
But I found cutting the block larger than needed and cutting a surface at 45-degrees makes it easy to start the hole. The drill depth needs to be as far as the outside of the 45-degree corner (on the right side of the outline of the bent hole shown on the paper template).
I used a drill press vise to hold the workpiece. If you don't have a drill press vise, you could clamp the block between two larger pieces of wood to hold it in place.
I hadn't drilled quite deep enough, so there was a bit of a ledge left between the two holes. I cut that out with a carving knife.
Testing the pump with the top exit block. All working ok. Normally, I'd use more riser blocks between the pump and the exit block, but making those is very similar to the exit blocks, so no need to go over that again.
An earier marble pump
build with my slot mortiser
Marble block plans
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