Change isn't always improvement

I love scarf joints. So sue me.

It's geeky, but who cares ?

In the eighties I came across this book:

Now it may not look enthralling, but you have to trust me: it is. Cecil Hewett was one terrific craftsman - a carpenter - and also an impressive historian.

What really caught my interest was his appendix on scarf joints. I'll explain why in a bit.

A scarf joint is used when you don't have a long enough piece of timber, and you need to join two or more pieces together end to end to get the length you need. The trick is to try to make the joint as strong as a single piece of timber would have been, and to make the joint as neat and invisible as possible.

A scarf joint can be in many styles, but this gives the general idea:

The scarf joint above is not very strong, and would only be useful where there was no strain.

This one is better, but still nothing like a strong as an unscarfed piece of timber.

And the one below is really good.

  
It is amazing that carpenters could cut such complex joints with the high level of accuracy the joint demands when they were using fairly unspohisticated tools. They did not even have pencils to make the marking out easier. 

If you want to see a scarf joint being made with modern tools, try this. (Go on. Try it !)

Now this is where it gets interesting. (Honestly !)

Carpenters kept on developing the joint to make it stronger. It became more complex and sophisticated and was widely used in all sorts of construction, from barns to church spires.


The thing is though, that as the joint developed over a period of a couple of hundred years and maybe 10 generations of carpenters, the joint began to get weaker. The strongest version was made still more complicated, and as subsequent changes were made, the scarf became progressively harder to cut, but weaker in use. Nobody seemed to notice that they had had a brilliant joint, and had ruined it.

It's a lovely image of change and improvement not always being the same thing. Sometimes what looks like improvement can actually be a backward step. 

The scarf joint is wonderful evidence of that.

I like that a lot.