Creating Custom Joints

Although there are many standard woodworking joints, once you experiment with your furniture design, you will inevitably find situations where a custom joint will look better, work better, or even possibly be the only solution, where parts need to be joined. The whatnot I introduced last time is a good example, with custom joints that I've never seen elsewhere.
The whatnot is one of my 100% Wood projects, and specifically could not use any metal fixings or glue. One of the easiest options to create a custom joint is simply to butt fit the parts together, and then secure by installing a dowel or dowels with glue (steel rods with epoxy are popular for joints with particularly small cross section, or where greater shear loads my be experienced). Ordinarily, these doweled joints cannot be relied on without glue, so I had to think of alternatives.

The solutions where not overly complicated. Most survived basically unchanged from the initial sketches I made (photo on left) and were tested out in spare material before committing to the actual build.

Firstly note the standard joints: Iris petals are joined to the flower body with dovetail housings, and body to stem with a round mortise and tenon. Iris stalk joins base with a fox wedged mortise and tenon. Iris leaves join the base with dovetail housings. And lily pad stalks join their pads with wedged through circular tenons.
Now let's look at the custom joints, starting with how the lily pads attach to the base.

The main solution came from adapting a Japanese joint, the okuri ari (housed dovetailed joint), and it demonstrates how familiarising oneself with a large range of standard joints is a good idea. By using three short dovetail keys, and access mortises, per pad, each pad could be dropped about an inch away from it's final position and slid home. A simple 'see-saw' lock mechanism was added to each fixing, such that when the dovetail key was fully engaged, the see-saw bar would move with gravity, and prevent the parts from being slid apart.

Alignment of the joints for each lily pad must be parallel, but the joints of different pads can be arranged independently. This is important, since the the pads closing together will lock the lily stems in place--we'll look at that joint next.
This initial joint is what is called totally blind, that is, none of the mechanics are not visible after assembly.
An slightly improved design has since been tried, and a video of that can be seen on my YouTube channel here.

The second custom joint is that which holds the lily stems in the base.

This is much simpler, and consists of vertical, square mortises in the base, into which fit the non-rounded sections at the bottoms of the stems.
Once the stems emerge from the mortises, they are rounded, which leaves shoulders that can be locked in place with half-round cut-outs in the edges of the base lily pads, clearly visible in the photo.
If glue were allowed of course, the rounded stems could simply be glued into holes drilled through the base lily pads and into the sub-base.

The last custom joint we'll look is the one which attaches the lily pad shelves to iris leaves.

The flat vee profile of the iris leaves put me in mind of a dovetail, and that's basis for the joint.
A cut-out was made in the edge of the lily pad which would accept the leaf profile.
The dovetail shape ensures the iris leaf can't pull away from the lily pad, but what stops it sliding down?
The iris leaves do taper in their length, and the fit was designed to tighten-up as the pad was lowered into place.
With glue, that would have been fine, but without glue it required an extra touch. 
Two small hardwood pins were driven through from the back.
Holes were pre-drilled, and the pins prepared square and slightly oversize. This combination ensures that the pins grip well and won't work loose.

Aside from these joints, a bayonet style fitting was used where the one lily stem passed through the lower shelf, along with the standard joints mentioned earlier.
In all, it was a fun build.

Next time you build something, why not challenge yourself to veer a little from those standard joints.
Watch out for the Whatnot 100% Wood Challenge video, which I'm just preparing to edit.

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