Steel wedge. 3-5 kg sledgehammer. Strike — log splits along the grain. Not across (like a saw) but along.
Why It's Better
Split board is stronger than sawn. Fibers intact, not severed. Water can't penetrate. Bugs can't chew. Split oak fence stands 40 years untreated. Sawn — 15.
Uses
Fence posts. Roof shingles. Barrel staves. Rail fence. Firewood (of course).
One sledge blow = 2 halves. Another = 4 quarters. From one log — 8 perfect pieces in 3 minutes. No chainsaw, no log splitter, no electric bill.