Marking Gauge

Marking gauges are useful in many ways. One of those is marking a line with or across grain to mark where you will cut. You can use a ruler to set a gauge distance or you can use the gauge to get a measure from another piece of stock. There’s multiple types of gauges. Some use a pin for marking, some a blade, some have two sets of pins. You can likely get away with using a pin gauge, but eventually you may want to incorporate a cutting gauge and mortise gauge. I’ve made myself a full set of the three and below I’ll show you how.

TOOLS

Required:

  • Hand Plane (#4, #5, Low Angle Jack, etc.)
  • Dovetail or Gent Saw
  • Marking Knife
  • 1/2” Chisel
  • 1/4” Chisel
  • Mallet
  • Drill and bit
  • Rasp or File

Optional:

  • Panel Saw
  • Coping or Fret Saw

INSTRUCTIONS

Start with a small piece of 5/4 stock. If you don’t already have one, use the optional panel saw to cut it out. I made mine about 3″ tall and 2 1/2” wide. This is preference so make it a size that fits your hand well.

Once block has been cut out, plane all sides smooth, flat, and square. From there, mark out the mortise for the beam. I made mine 5/8” square, centered horizontally and about 1″ from the bottom.

I opted to drill out the majority of the mortise, but you can just you a chisel if you don’t have a drill or brace.

Use a chisel to finish up and square out the mortise. Then, mark the lines for the wedge. The wedge mortise will sit about 1/16” below the top of the beam mortise. This allows the wedge to engage the beam and hold it in place. The wedge mortise will be 1/4” wide while 3/8” long on the small side and 9/16” long on the large side.

This mortise is long so I opted once again to use the brace to drill out the mortise hole. Drill in from both sides and meet in the middle. Also note that I included a small piece fitted into the beam mortise. This prevents any blow out inside the mortise. Keep this in place while chiseling out the mortise as well.

Next, you can create the beam. You can do this before or after the wedge mortise. Just take a shaving or two off one side and fit it in the mortise. It should be snug, but still slide fairly easily. In the picture above is the beam for the mortise gauge beam. This is just two beams fitted together. Note that the mortise hole for this one is a bit taller at 3/4“.

Next it’s time to cut out the wedge. It is just a sloped piece with a round stop at the small end. I used a fret saw to cut out the rough shape, but you could use a chisel to slowly carve out the shape. Use a chisel or sand paper to round the corners. Take shavings and test fit into the mortise. Again, snug but can still move freely.

Joinery done, next is shaping. Mark a small radius around the top corner of the gauge fence. Then, use a chisel to slow chop away the corner until you’re close to your line. Once it’s close, you can start chiseling around the corner trying to follow the line with your chisel. This takes some practice to get your chisel control down so try it on scrap first if needed. Roughly shaped, a rasp or file can smooth it off.

Next, is to cut the slope on the lower back side of the fence. Before you do this, make sure to decide which way you want the wedge to operate. Hold the gauge in your hand, your fore finger should be placed over the top of the fence and touching the wedge from behind. Your thumb should be touching the wedge up front. Decide which finger should tighten or loosen the wedge so you know which way the fence will face. Once you’ve decided, you can make a 45 degree cut down the lower back side. Keep in mind, this is entirely optional.

Now, the tough part is setting the cutter. As for the pin cutter, I simply used what’s called a doll needle. It’s basically a sewing needle you can pickup at any craft store. Use some clippers to clip off the eye and file the end so it isn’t sharp. Mark a spot about 1″ from the end of the beam and slowly start to hammer the needle into the beam. Go slow because you don’t want to split the beam. In the case of the mortise gauge, you’ll do the same thing except you need to make sure both needles can operate together. Pictured above are the slots cut to allow for both needles to work together. A needle will be embedded into each beam and ride along the slots.

The cutting gauge is next. I wasn’t able to find anything the right size and shape so this took a little metal working. I found an old hacksaw blade and cut out a small piece about 1/4” wide and 1 1/2” long. I took the piece to my sharpening stones and cleaned off all sides and edges.

While still at the stones, I shape the end to a point and slowly round it over and create a bevel. I then sharpen it so it cuts cleanly.

Last step is to create a small 1/4” mortise to accept the cutter and shape a small wedge to hold it in place. The above picture shows how to get a measurement from another piece of stock to use to mark another piece.

That’s it! You’re done! The gauges are done and ready to go. A light sanding is recommended and will make all parts slide much more easily then before. Optionally, you can add a finish such as Danish oil, Linseed oil, or paste wax. Just nothing too slick because it could prevent the wedge from engaging.