I've built numerous benches using everything from particleboard (everybody's a beginner at some point!) to MDF and hard maple. And all of those benches had a different type of bench dog. But now all of my benches feature shop-made wooden square-section dogs with a wood spring, stepped shaft, and leather face. Here's why.
- I can make a batch of dogs for every hole in my bench in about 2 hours, and I'll have enough dogs for the rest of the bench's life, even if I loose or ruin a few. And the total cost is just a few dollars, since most of the wood can be had from scrap.
- The step in the shaft makes a flawless, effortless depth stop. I can push the dog down and be guaranteed every time that I won't push it through the bench to have it fall completely through. It requires no thought, no tedious adjustment to make sure the dog is below the surface of the bench.
- The wooden spring holds evenly throughout the vertical travel of the dog, yet allows the dog to slide up and down easily due to the wide bearing surface against the inside of the hole.
- The suede leather face provides a fantastic grip against the workpiece, allowing lower clamping forces and thus less chance for bowing or damaging the workpiece.
- Square dogs can be raised high above the bench surface for more versatile workholding.
- Wooden dogs have no exposed metal to bang into plane bodies or cutting edges.
- Square dogs are always parallel to each other. 99% of my between-dog clamping has always been with parallel-ended workpieces.
And here's why I don't like all the other versions of dogs that I've tried.
- Round dogs rotate in the hole. In my experience, 99% of furniture and cabinetwork is held between parallel-ended boards. I can't remember the last time I needed a dog to rotate a few degrees to hold something that was just a tad off parallel. Anything beyond a few degrees and the clamping pressure would pop the workpiece out anyway.
- Round dogs require a less-than-ideal device to hold them in position. This device, whether its a wire spring or a bullet catch/spring plunger concentrates the force in one small area. I found that the wire spring can wear a groove in its hole (its mounted on the side, so it bears against edge grain), and the bullet catch shares the same problem. The bullet catch also requires a very smoothly drilled or milled hole to work nicely. If the hole is rough on the inside the bullet catch with cause the dog to move in jerky movements, and over time can cease to function entirely with wear. The threaded spring plungers do have some adjustability, but they are pricey. The commonly available bullet catches are cheap, but have zero adjustability. The bullet catch also has to be positioned precisely to get the most travel possible. It's also too easy to push the round dog past the bullet catch only to have the entire dog fall through the top and inevitably roll under some inaccessible place.
- Square dogs with bullet catches solve a couple of these problems, but the issues with the bullet catch remain.
- Commercial round dogs are made of metal, like brass or aluminum. When I built my first real bench after high school I outfitted it with round brass dogs. One day, while planing a thin board, I ran out of wood and my next stroke clipped the top of the dog. If I had been using a wood dog, I may have chipped out the end grain at the top of the dog instead of chipping both my plane body and iron. I have nicer tools nowadays, so there's no way I'll willingly place a metal barricade in the path of a finely tuned smoothing plane again.
- Commercial square dogs made of metal. I never understood these. They have all the advantages of my favorite dogs, but are not only made of metal, they are steel. Why risk it? Nobody needs the shearing strength of a steel dog for woodworking. If you're breaking an ash dog you're doing something wrong.
- Routing square dogs during a bench build allows you to cant the holes so they slant towards the end vise. This aids in holding workpieces to the bench top. This is difficult with round holes. Drilling a bunch of round holes in a thick bench takes longer than you might think. I can make a jig for routing square holes and have them routed in just a few minutes more than drilling round holes.
Here's the drawing of the bench dog from our Split-Top Roubo Plans.