Build a Dedicated Dog Hole and Tail Vise System for the Workbench
Dog holes and a tail vise transform a basic workbench into a versatile workholding platform. Dog holes are round or square holes drilled in a row along the bench top – they accept bench dogs (round or square pegs), holdfasts (curved iron hooks struck into the hole to lock work), and a range of commercial and shop-made accessories. A tail vise provides a second point of clamping, so work held between a dog in the vise and a dog in the top is locked firmly without any lateral movement. This guide covers both building dog holes into an existing bench and adding a simple shop-made tail vise.
Dog Hole Spacing and Diameter
The standard dog hole diameter for round dogs is 3/4 inch. Some benches use 3/4-inch square holes, which offer more surface contact but require a square dog or a square-shank holdfast. For a new installation, 3/4-inch round holes are easier to drill and the most commercially compatible with accessories. Space holes 4 inches on center along the front of the bench, starting 2 to 3 inches back from the front edge. Run the row for the full length of the bench or at least the full working area.
Drilling Dog Holes in an Existing Top
Use a 3/4-inch Forstner bit in a drill press for the cleanest holes – a hand drill produces holes that are rarely perfectly vertical, and a dog in an angled hole doesn’t function correctly. If you don’t have a drill press, build a drill guide from scrap plywood: a block with a precisely perpendicular hole that clamps to the bench top surface and guides the bit straight down. Drill slowly through both layers of a doubled top to prevent tearout at the bottom of each hole.
Building a Simple Tail Vise
The simplest functional tail vise is a wagon vise – a sliding block mounted in a cutout at the right end of the bench. The block slides out to accept work between the bench dog in the block and a dog in the top, then is pushed in to clamp. A threaded rod and nut mechanism drives the movement. This is significantly simpler to build than a traditional tail vise with a wooden screw and requires only a tap and die set, a threaded rod, and a shop-made wooden sliding block.
Installing the Wagon Vise
Cut a mortise in the right end of the bench top – typically 4 inches deep, 3 inches wide, running from the front edge to about 6 inches from the back edge. The sliding block fits in this mortise with 1/16-inch clearance on all sides. A guide strip on the bench underside keeps the block aligned. The threaded rod passes through the bench end, through the block, and is captured with a washer and nut. The handle projects from the bench end and turns the rod. Dog holes in the sliding block align with the row in the top when the block is at various extension positions.
Pro Tips
- A holdfast in a well-fitted dog hole is one of the most versatile and quick workholding devices in the shop. One strike of a mallet locks a board; one upward strike releases it. Keep a pair of holdfasts within reach of the bench at all times.
- Round bench dogs should tilt slightly toward the work (lean in the direction you push work against them). A small angled cut at the dog hole bottom, or a dog with a beveled face, achieves this.
FAQ
Can I add dog holes to a commercial workbench?
Yes, if the top is solid wood or solid laminate and at least 1.5 inches thick. A laminated plywood top drills easily. A particleboard top is not suitable – the material won’t grip a holdfast and crumbles around the hole edges over time.
What’s the difference between a tail vise and a face vise?
A face vise is at the front left of the bench and clamps boards vertically for edge work. A tail vise is at the right end and clamps boards horizontally on the bench top surface, working in conjunction with bench dogs. Both have very different functions and a well-equipped bench has both.