Dovetails in the round

Detail of the author’s rotating dovetail – a turned and chiselled evolution of Sam Maloof’s chair joint. Photo: Mike Roberts

Words and photos: Alex Peay

What is a rotating dovetail? The best way to describe the rotating dovetail joint is by comparing it to the joint most people are familiar with, the Maloof joint. Visually and in application, both joints are quite similar; the difference being the obvious addition of a dovetail, the rotational movement of assembly, and the structural benefit of its locking mechanism.

I’m Alex Peay, a Spring, Texas resident whose passions away from woodworking are music in all types and forms and…tacos. You’d be forgiven for assuming that I’m really just a simple man.

My path to this wood joint began in April 2020. The world was in the middle of a global pandemic. Through the chaos I was working retail at a hardware store and in desperate need for a cathartic outlet to quiet my mind. I found myself watching YouTube one evening and a video of someone making a chair caught my attention. I thought to myself, ‘I bet I could probably do that’.

Armed with a limited set of tools I used while building fences, I began my woodworking journey. Very simply at first, making cutting boards. Then a workbench, and after that a headboard for my daughter’s bed. With every project my skills improved. Fast forward to August 2021 and I completed my first chair. I was hooked.

Around that time, I was also learning hand cut dovetails. I was putting them everywhere just so I could practise. What was my next project going to be that I could put dovetails in? And then I came across a Maloof rocker. When the feeling of awestruck subsided the next thought surfaced quickly: Could I put a dovetail in a Maloof joint? Two years from that thought, shouldered with the drive, curiosity and passion I’ve met with every one of life’s decisions, I answered, ‘I bet I could probably do that’, and I cut my first rotating dovetail. The sequence A–H shows the process on a sample joint.

Fig.1, dimensions (not to scale)

The equipment

First, I’ll go over the tools I use: router table (dovetail and straight bit), lathe, drill press, forstner bits, track saw, flush cut saw, planes, chisels and card scrapers. I use these tools mainly because they are the ones I have access to and I’m most comfortable with, however some of these processes can be achieved in other ways. For instance, if I didn’t have a lathe, I could buy round stock or use a dowel making jig. The drill press is convenient, but I could also use a hand drill. The joint consists of two pins cut into the leg and one tail in the seat. Yes, it’s only two pins and one tail – you can just see both ends in fig.1. I’ll begin with square stock.

Measurements and increments

Before I start any of the joinery, I need to know the finished thickness of the seat for a set of shoulders I’ll add to the leg later in the process. For the seat thickness I’m shooting for around 1-3/4" or 45mm. Let me just take a second to say something that’s probably pretty divisive in the States. If I could go back and buy all of my measuring tools in metric I absolutely would. Is 3/32 bigger or smaller than an 1/8 – I know you had to think about it! However we use imperial measurements in the US, hence their use in this article.

Knowing the finished thickness of the seat I can start the leg portion of the joint. I’ll be referring to three different diameters here: an inner 1-1/4" (32mm), outer 2" (51mm), and overall diameter 2-1/4" (57mm). The inner and outer diameter directly correspond to the size forstner bits used to cut the seat socket. The overall diameter can be any size that I want. The difference of the overall diameter and the outer diameter divided by two will be the width of the shoulder and will extend out over the seat as the joint is rotated together.

A. The 2” outer diameter is cut 1-3/4” wide to equal the finished thickness of the seat. A 2” recess is drilled 1/4” deep from both sides with 1-1/4” hole.
B. A 5/8” wide slot is cut slightly larger than the inner diameter of 1-1/4”. The seat socket is cut in half.
C. The inner diameter is defined to 1-1/4” using a dovetail bit while also widening the slot and cutting the dovetail angle. The ends are tapered.
D. Relief cuts are used to establish margins and give something to work towards.
E, F. The ‘pins’ are roughed out using planes, chisels and card scrapers.
G. The tail is cut with chisels after the pins are marked out and transferred over from the leg.
H. Showing the finished rotating dovetail joint sample in walnut and hard maple.

Machining the parts

First I turn my overall diameter on the lathe. Next, I cut the outer diameter on the router table. I will position my fence, so the leg is centred over the straight bit. Stop blocks are used along the fence to keep my margins nice and crisp. I rotate the leg while keeping in contact with the table and fence as I move towards each stop block making sure to rotate the leg counter to the rotation of the router bit. When I’m done my outer diameter along the length of the leg should be equal to the thickness of my seat (A).

Now I need to cut a slot in the leg that’s pretty close to my inner diameter. I do this on the lathe. The width of the slot for me is just wide enough to get my dovetail bit into the slot safely (B). I then take the leg back to the router table. I’ll raise my dovetail bit incrementally to define my inner diameter. Then using stop blocks again I cut the dovetail angle in the pins. Again, I make sure to rotate the leg counter to the dovetail bit. The slot is then widened to about 7/8" (22.25mm) with the dovetail bit. Once the pins are cut, I take the leg over to the lathe and taper each end (C).

Then it’s time to open up the joint. I will use my wagon vice for work holding. First I’ll make two cuts to give me something to work towards (D). I don’t quite halve the joint as the edges tend to bruise when fitting. I’ll plane down to my inner diameter and then use a series of chisels and a flush cut saw to finish opening it up (E, F). Slowly I’ll see the pins start to make their way to the surface. I keep it pretty rough at this point and will shape it into its final form after I’ve glued the joint.

H. Showing the finished rotating dovetail joint sample in walnut and hard maple.

Cutting the ‘tails’

It’s time now to cut the tail portion of this joint. I’ll be using a 2" and 1-1/4" forstner bit on my drill press to do most of the heavy lifting. When I first showed this joint to the internet, I got a lot of questions on how I cut the half circle. There are indeed many ways to cut a half circle. I found the easiest way for me was to cut a full circle and then cut that circle in half. There were also many suggestions on how to cut the circle with the dovetail angle included – all plausible, from a custom ground forstner bit to a custom ground rosette cutter.

I found the seat socket much easier to cut and more precise if I fit the tail to the pins by hand rather than using a custom ground cutter. It takes spindle runout and any mistakes I’ve made cutting the pins out of the equation as I’ll transfer the pins onto the tail with a marking knife.

It’s important as I cut the seat socket that I drill from the same position on each side of the seat. I mark out my socket locations meticulously for visual reference, but I rely heavily on stop blocks and a fence – especially since I need to switch from the 2" to 1-1/4" bit during this process and I’ll lose any reference marks I’ve made.

The 2" bit is up first. The depth of this cut depends on how far apart you made the pins on the router table and how thick your seat is. For me it was about 1/4". After the 2" bit I’ll move to the 1-1/4" bit. I will get some tear-out as I exit, but I’ll be paring that off with a chisel in a moment. After the socket is cut then it’s time to cut it in half. I use my track saw for cutting this joint in half, but I could use a tablesaw as well.

I’m on the home stretch now as I mark out the tail. I should be able to press fit snugly the leg into the seat socket and have it stay while I mark out the tail with a marking knife. Then I just go after it with my chisels. I use a template made with my dovetail bit to let me know when my angle is correct. Then I’ll start to test fit. I make this fit extremely tight and a strap wrench gives me the leverage I need to make the rotations.

I’ll end up burnishing the two surfaces as it rotates in to identify high spots and tend to them. It sounds like I’m breaking the joint during the fitting process, but honestly – I don’t know what it would take to break one. The burnishing of the two surfaces also has another advantage when glue is eventually applied to the joint. The water in the glue will swell those burnished areas and gives extremely clean lines. The pins from the leg will be proud of the seat socket, but those areas are mostly full of bruises from the fitting process. I’ll pare them down after glue (G) and then joint is complete (H).

Cutting the dovetail angle on the router table using a dovetail bit.

Marking out the ‘tails’ with a marking knife.

Planing down to the inner diameter to open up the joint.

Using chisels to continue opening the joint.

Using a 2” forstner bit to drill the joint socket on a seat blank.

A step is next created in the socket with a 1-1/4” forstner bit.

Chiseling the dovetail angle in the tail.

A flush cut saw finishes off the opening process.

Frequently asked questions

Sometimes I’m asked about expansion and contraction of the wood as it goes through the seasons – won’t it split? This is definitely a possibility, but let’s take into account the shape of the joint and how a butterfly or bowtie is used in furniture.

I also get asked why I cut it into endgrain rather than side grain. The truth is that just happened to be how I cut it the first time, but there are some practical reasons why endgrain is advantageous. It allows for cleaner lines as I chisel out the tail. It also puts the location of any tearout from the 1-1/4" forstner bit to a portion of the joint that will not be seen and or pared away.

This joint is extremely challenging to make, but not unattainable. It has a lot of steps that include meticulous planning and foresight. Let me tell you though – the feeling of getting it right is unmatched in any other joinery I’ve completed. When I first started woodworking, I had one goal and that was to make something that would outlast myself, something tangible that my daughter could carry with her after I’m gone. I feel like I’ve done that here. I wish you the best and hope you find success not only in cutting this joint, but in all the things that give one purpose.

Alex Peay @peay.alex is a hardware store manager by day and a keen woodworker by night. Learn more at https://www.alexpeayfurniture.com/ and see his YouTube channel @alexpeay where you can also watch the build process.