These devices are fascinating. Some complex, some surprisingly simple. Can't say that, for the cost, the modern ones are more efficient and safer than some of the home built ones. However, some home built ones are potentially highly dangerous

Interesting devices. Major labor savings, but losing a digit or limb is a risk. I've split a lot of wood as a teen with an ax, sledge hammer and wedges. The oak with knots were particularly tough. Risks with my ax and hammer too; mostly to putting out an eye and I didn't have the sense to wear safety glasses.

Had a relative missing a fingertip from a splitter accident maybe 70 years ago or more now. He always said the machine spun and you had to throw the logs in... and I could never get my head around what kind of machine he was describing, but now I have a least a much better idea.

Number 7 was the only one slitting hardwood, everyone else just on pine. Pine splits so easily, when or dry. Grey box or redgum dont split so easily. Notice how the Hydraulic blade has to go all the way through, not just strike it. Wood splitting in Aus is a lot more work, though because it burns longer, you don't need as much.