Wednesday, November 30, 2011

Over the Top

bent things going straight

The glue is dry and the bottom is assembled, so here I am trying the final bits dry before doing the glue part.

If you look at it above, there will be some fitting problems because the left side verticals are a tad short when they are seated all the way down their respective holes. And, how will I hammer the bent bits into the holes without making marks on them?

The solution I plan to use is merely to not seat the verticals all the way down. I can do it by dropping a short spacer into the hole to prevent them from going all the way to the bottom.

It is the tight fit at the sides that does the glueing, and the fit is good. So I will sacrifice some strength at the bottom to get some at the top.

The other thing to see is how I plan to tap on the curved hoop to seat it in its holes on both sides. It is so springy that normal tapping on the centre  of the curve will not work well.

Here is a closer look at the hand screw type of clamp which is very useful as well as being extremely powerful as a clamp. The two handles allow the top bit to spread the outer ends, closing the gap with great force at the hinge part.  Makes a good nut cracker too.

You got the glue tutorial in the previous posting so I am not going to repeat it here, just remember that I planted the four sticks in the middle and waited for the glue to dry before going on to the hoop part.  Patience is a real virtue in wood working. The ability to pay attention to details and plan ahead is also crucial. But the real test of skill is in how to cover the mistakes.

As Howard I Chapelle wrote in his book about building boats, you need a Moaning Chair to sit in  while thinking of how you did it and how to recover gracefully.

Here is the hoop and its little wedges ready to install. See how much closer the ends are than the holes they will occupy. Its quite springy.

So there it is - assembled and glue dry with the wedges sticking out from the bottom, where I merely saw them flush with my nice Japanese razor saw.

And with the little curved braces installed it is ready to finish.  For a project like this I prefer to use a traditional finish, not the factory one. I first rub a few coats of linseed oil on with some fine steel wool. Then I wax it.

A few clues about using linseed oil are appropriate here.  Its cheap, edible in the raw state (used as a cattle laxative) and bio degradable. Don't use that stuff.

Use the boiled linseed oil which is more suitable because it polymerises to a film instead of remaining permanently sticky like the raw stuff does.

The next clue is that as it dries, and the chemical reaction to oxygen in the air takes place, it puts out heat. Hence the warnings about oily rags. Its the linseed oil that's the usual culprit.

It suffices to either place the rags in a water filled container as per the techno sophistoes, and then contend with all sorts of storage problems and mess when it is time to throw out the garbage.

Or do it my way. My way is too easy and really cheap.

Lay them out to dry flat. (I lay them on the concrete floor overnight, but really any surface will do.)

Or hang them on a line, flat. The heat has plenty of area to radiate from so it never builds up. It is as thermally safe as the oil drying on the wood you just oiled.

For a fire you have to scrunch the rag up into a small volume where the heat cannot escape easily and there is a supply of oxygen for the reaction to take place and eventually the heat builds to combustion temperature.

In my shop I once tested this and a tightly folded oily rag began to smoke after about four hours, so we flattened it out and it cooled right down.

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