Building a book press (part 2)

The lead screw (pronounced leed)
The lead screw has acme threads—great for transferring motion instead of fastening one thing to another. Another term is motion translation, as when we convert rotary motion (turning the screw) to linear motion (moving the platen down).

As you know if you've been attentive to this entire lesson, my acme screw came from an old automobile scissor jack. Its specs are 3/4" diameter and 6 threads per inch.

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Learning opportunity

Look, it's a diagram. Don't we all love diagrams?

Notice the flattened tops and bottoms on the acme thread?

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Connecting the lead screw to the bridge
The thoroughly cleaned (more or less) lead screw with the nut attached (right). This is the nut that you see in the picture below. See how it all comes together?














Bottom of bridge showing acme nut epoxied into a roughly hexagonal hole.
I use the term  "roughly hexagonal" because I made that hole with a chisel and hammer. Epoxy addresses and forgives a multitude of sins.

















Nothing lost in translation
Here, the lead screw is fastened to the bridge, and moves up or down as you turn it. See—rotary motion to linear motion. It's a miracle.

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Next, the finished product

Building a book press

Just as you would think, a book press is for pressing books, their covers, and their pages. This operation flattens irregularities and curling, and also also binds the book together as glue dries.

Most presses look something like this (but not red).

Cast iron book press

Let's build one
Because they are now considered collectibles, book presses are fairly expensive. Whenever you see a price tag hidden from view (above), you know it's going to be bad news.

So of course, I decided to make my own with scrap parts and a few flea-market finds.

Most presses are steel or iron, but some are wood. The one I build will use both materials.

The first parts
This is an old car jack—a flea market buy for $10. The acme screw it contains is just what I needed, and a new one would cost more than twice that amount. Of course, my labor is free.

Old car jack with acme screw and an old vacuum-tube radio

The flea-market radio will not be used for the book press project. In case you're interested, it was also $10, and its price tag was plainly visible.

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Building the book press
The picture below shows the base and two pipe columns. The pipes will support a bridge that holds the screw and platen.   

The base, bridge, and platen are made from glued-up sections of a shelf that was destined for the trash.

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Laying out and cutting some curves on the bridge
The bridge is shown here after gluing together three slabs of wood, marking the curves, and cutting with a band saw. The tangent-curve procedure was still in my brain after teaching geometric construction for about twenty years.

Arrows point to the barely visible curve construction lines

Following the curves with the band saw

The bridge after cutting but before sanding

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So far, it fits—but there is much more to be done.

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Next, installing the lead screw in the bridge