Thread: When to use what Join

I am no expert on Joinery even that I have a great interest in it. While joints act to hold things together they must also act as a means to counteract the forces the object's may encounter, such as racking or twisting. If you study classical plans for large carcasses you can see a variety of joints used in specific places.

You must ask what forces are acting on this location, and in what direction are the likely to act. This will give you a bases for the selection of joints.

It is important to remember that while dovetail and M&T are the most common in modern furniture their are thousands of variations even in western furniture making, much like that found in Japanese Joinery. Each of these joints served more then a decorative purpose and are based on principles of mechanical engineering.

There are many ways to skin a cat. Which joint you choose for a given situation will depend on a lot of things, including your level of skill and the tools you have. To a lesser extent it might also depend on the material you are using and the glue, or lack thereof.

For example, if you are making a carcase from a man-made board like ply or particle board, you are unlikely to want to use dovetails and would be more likely to use a rebated joint or just screws.

For a solid timber carcase, you can use dovetails, mortice and tenon, rebate, box/finger joint, reinforced butt joint, reinforced mitre joint - there are many options and each has its advantages in strength and appearance.

You might make a stand or a frame using only wedged through tenons - no glue.

The best thing is to learn and master as many joint types as you can and then you will know which ones suit what applications.

A lot of people find a joint they like and use it for everything (Domino or biscuit joints come to mind). There is a lot to be said for that approach. You can set up for it and become very efficient at making things. It may tend to constrain your designs to suit the technique though if you start to think of how you're going to construct it too far in advance.

I like to try different things. The last cabinet I made had a total of 4 dovetails in it, all the rest was mortice and tenon - but that was because it was a frame and panel carcase. I made a solid timber carcase a while ago which was dovetails all the way.

So in short, I don't think there is a single answer to your question. Dovetails have stood the test of time for a reason, as have mortice and tenon joints. But there are other options equally as valid in given situations.

Originally Posted by thumbsucker

... While joints act to hold things together they must also act as a means to counteract the forces the object's may encounter, such as racking or twisting...

...You must ask what forces are acting on this location, and in what direction are the likely to act. This will give you a bases for the selection of joints...

G'Day "Blue Balls"

Man has TS nailed this one. It is one of those things that tends to be forgotten in these days of man made timber (ply, MDF etc.) When using true wood, the joint needs to be functional as well as aesthetically pleasing.

By all means make it look good, but not at the expense of the joint.

Makes me wonder though about Rocker's half-Z assemblies, man they look good and from all posts seem to be solid enough, but I think I'm going to have to watch this thread: http://www.woodworkforums.ubeaut.com...ad.php?t=57750


BlackAdder

My own person rule is:

Use the simplest join that is strong enough to perform the task.

The exception is dovetails, which (personally) I would only use if it was important cosmetically.

e.g. if I make drawers, if they have a false front (such as kitchen drawers), then I will use simple lap joints. These provide suitable strength for 99% of the time, so the complexity of dovetails (which you won't see) is unjustified.
If the drawer front is exposed, then I would still use lap joints, unless I wanted to make an aesthetic statement with dovetails. Sometimes I have used box joints for that reason.

For framing, the order I would consider (off the top of my head) would be something like:
- simple butt joint (e.g. kitchen carcasses)
- biscuits
- Pocket screw butt joint
- half lap
- floating motice and tenon
- proper mortice and tenon

As you go down the list, each option is slightly stronger, but also slightly more complex to make, so thus I go for the simplest join that is strong enough.

Of course, there are always exceptions, which is why there can be no absolute rule.

I tend to agree with two exceptions:

1) I would place a biscuit joint higher up the list than that. Testing of them has actually positioned them up with floating tenons.

2) I think dovetails should be first selected for their strength and second for their appearance. I believe that the kudos attached to dovetail joinery has come about because they are a sign of something designed to last - they don't have to be pretty to be strong and I would always prefer a half blind dovetail for a drawer front over anything else and they are not at all difficult to make.

Hi Blackadder,

Google

Reitveld z chair

They're not a new design, and rather well done.

I'm interested in the results, too.

CHeers,

eddie

John G,

I'm partial to dowels for face frames.

BlouBull,

A lot of the decision depends upon what you want the final result to look like. If you want to show off your skills, you might choose through tenons or dovetails. If you are trying to make your project look like it was made professionally, you might use mortise and tenon.

The best answer is to use the joint that is correct for you and your project.

BTW - Most people only look at the joints when they fail.

asthetics and strength are not the only factors in considering joints

the quality of the work, the materials and what the customer will pay also have some bearing on the joints you chose


for example you wouldnt use dovetail joints for drawer carcasses made of 12mm mdf