Introduction: Wooden Marking Gauges
As a beginner and amateur in the woodworking world, dovetails seem to be the only way to attach two pieces of wood. To mark the base of the dovetails with precision a wheel marking gauge is commonly used. There are various commercial options but I did not find one that I could say: "I want to buy this one!". Taking advantage of the typical design that you can find everywhere I decided to make my own set, after all, there is something satisfying in using your own tools. Why a set? Because often the two pieces that are being used have different widths.
The tools that you will need to make these marking gauges:
- Wood lathe and turning chisels;
- Metal lathe and M3 taps;
- A drill, drill press and drill bits;
- Sand paper;
- Workbench with a vise;
- Vernier caliper;
- 12 mm countersink bit;
- Center punch;
- Plug cutter (5 mm)
The materials that you will need:
- Wood pieces that you like the most with at least 5 cm in width;
- Brass tubing;
- 2 M5 brass bolts;
- 8 mm stainless steel rod;
- 2 marking wheels and respective M3 bolts;
- CA glue;
In total, I think that by spending ~20 mins after work I took 2 to 3 weeks to do this small project. It came out better than I expected.
Step 1: Select the Wood
This is a personal thing. I selected olive wood and padauk. Olive wood is very fragrant when it is being worked, where I live is ubiquitous and creates a nice contrast with padauk. In this way, I'm able to quickly distinguish the marking gauges. Here I drilled two small holes to turn the pieces of wood between centers in the lathe.
Step 2: Turning the Handles
Here you can be as creative as you want. I went with a regular shape to fit my whole hand in opposition to the most commercial options. In one extremity I glued wit CA glue a small ferrule of brass tubing and in the other I turned a circular part that will later contact the wood when you are marking the wood. I used the olive wood one as a template when started working in the padauk marking gauge. Since I'm a beginner in wood turning I started the parting making sure that the resulting surface was flat and later finished the rest of the cut with a saw. A coat of shellac as applied at the end.
Step 3: Boring the Holes for the Rod
This is the part where the handles can become firewood pretty quickly. Since I do not have a chuck for the lathe I went with a drill press to bore the holes for the stainless steel rod. I took extra time to make sure that the drill press base was precisely perpendicular with the drill bit and took my time. Since I will use a 8 mm stainless steel rod, I used a 8 mm drill bit. The drill bit was barely long enough to make through the 11 cm handles. I used a 12 mm countersink bit to create a small chamfer that will be handy to hide the blade.
Step 4: Drilling and Tapping the Threads on the Rod
I do not have a metal lathe (yet!) so I had to go to a machinist shop to cut some perfectly concentric M3 threads on the stainless steel rods. It was an affordable service (~ 7.5 €) and the end result is good. I also cut previously the rods to length (19 cm).
Step 5: The Securing Bolt
Since the rod slides freely on the handle (preferably with zero play) there should be a way to secure it. A transversal bolt is usually used and that was what I also considered. I bought some M5 brass bolts on Amazon. To be honest, an M6 bolt would be more suitable, but the M5 ones do the job just perfectly. Since these were just the typical brass bolts on Amazon I decided to add a little touch and added a small plug of olive and padauk wood to each bolt. The machining marks on the bolt make finding the center very easy to drill the hole for the plug. Used ca glue to secure the plug, the vise to act as a press to insert the plug on the hole and sand paper to finish.
Step 6: Drilling the Handles for the Securing Bolt
In this step, a threaded insert should be "inserted" on the wooden handles so that the brass bolt can be used. I used an improvised threaded insert from a threaded brass expansion anchor. Drilled a though hole for the bolt, and a hole at the right depth for the brass insert. To make sure that I was drilling at the top of the handle, something flat between the drill bit and the piece may be used to see if things are aligned. Used a saw blade and it worked just fine. CA glue was used again and the vise helped to insert the brass insert in the hole flush with the surface of the handle. At the end, since I made a mess with CA glue I had to use an M5 tap to clean the threads.
Step 7: Sharpening the Blades
This is a basic step but needed. I bought these blades from an online shop in Germany, and as the seller advertised, they were not sharp at all. Some 1000 and 2000 grit sand paper work just fine.
Step 8: Assembling an Testing the Marking Gauges
By this step you should have something that resembles a marking gauge(s) ready to e assembled.
Step 9: Test the Marking Gauges
Before cutting wood, the marking gauge should feel comfortable in the hands. The securing bolt may seem tout of place but it does not get in the way and the handle is really ergonomic to my hands.
Making sure that the hole for the rod is perfectly centered with the handle contributes to the precision of the piece, you can turn the marking gauge and it cuts always in the same line.
Step 10: The Final Inspection
At the end, my inspector approved the work but he was kind of tired after so many steps. Can't wait to make some dovetails.