Log dogs, also known as timber dogs or spike dogs, are really just big metal staples that hold two logs in place while you work on them. They’re more of a clamp for logs than a hand tool. You’ll need at least two log dogs, one for each end of the log you’re working on.
The ends of the log dog are sharpened to a chisel edge so they can be driven into the grain of the wood. Usually the tips of the dogs have edges 90 degree to one another, making it possible to drive both ends of the staple into the log “with” the grain when the logs are 90 degrees to one another. The ends of the dogs are pounded in along the grain of the the wood, not across it. Some log dogs have square spikes but I find the spiked ends are more difficult to pound in and don’t hold as well as a chisel edge.
The best log dogs are hand forged with quality mild steel. The corners of the steel should be “upset”, not simply bent into a 90 degree angle. It should have a sharp 90 degree corner that you can hit squarly with your hammer. An upset corner is thicker at the corner, a slight bulge will be evident.
You can make log dogs if you have access to a blacksmith’s shop. Below is a video of my hero, a young Roy Underhill, showing you how to hand forge log dogs. BTW – If you like the video below, you can watch the full video, and more like it, at Popular Woodworking.
You can also buy log dogs online. There are places that sell high quality hand forged log dogs. Gransfors Bruks of Sweden produce excellent quality log dogs.