Saturday, April 20, 2013

Working with Partially Decomposed Wood-Discussion and Project

Hi Everyone,

Well the sun finally came out today and the temperature has warmed up to a whopping 38 degrees so I'm going down to the wood shop-wood turning weather has arrived.

Working with partially decomposed wood

I live in a wooded area that contains a lot of tree limbs and trunks that have either died or fallen as a result of storm or winds. That leaves a lot of potential turning wood laying around that can be used in your projects.

I've done a very limited number of turnings using this type of wood and I'll share some of my observations with you:

  • This wood has been dead for a while and laying out doors in the weather so it's partially decomposed. The wood fibers, both visible and invisible, are beginning to break down as the result of the activities of microorganisms and insects. So even though the wood appears solid, it can be fragile. My point here is to treat it as a potential accident waiting to happen. Don't turn this at high rpms, wear lots of protective head and face gear, and if you have a turning cage on your lathe, use it. Don't use badly cracked wood and if you can, use turning tape or duct tape around the blank to keep it intact while it's turning. 
  • The end grain of this wood easily tears, living a pitted surface. You'll need very sharp tools to cut it with and even with sharp tools, it's difficult to achieve a smooth surface. Plan on this when you're contemplating designing something out of this type of wood.
  • Smoothing the surface of this type of wood can be challenging. Since a lot of the fiber has decomposed away, it tends to have a finely pitted surface. It's difficult to remove turning scratches so turn carefully and slowly. 
  • Oils don't seem to be the best way to finish this type of wood. The wood is spongy and it tends to absorb the oil unevenly resulting in a muddied finish.

  •  I'm going to experiment with some polyurethane and lacquer and see how this works out.
Having said this this wood has a lot of possibilities. It's available in large chunks and it's either partially or completely dry so it's useable and you can leave the pith-center in the wood and turn it. And since it's round in shape, it's super easy to make a box.
I think if you're careful, this can be a very fruitful source of wood for the more experienced turner.

Small Project-M&M Box

I decided to see how a box would work with a piece of an elm tree that was on my property. I sawed off a 4" piece off the end of a large branch, prepared it for mounting on the lathe and proceeded to turn it.

I've removed the bark and brushed the surface of the blank. Then I turned the lathe on to about 100 rpm and sanded the surface with a green nylon kitchen scrub pad to remove any dirt and to smooth the surface:

Next I drilled out the center of the box to aid in hollowing it and to establish a depth:

Now I'm hand turning the blank. I'll widen the opening and deepen the bowl:

Here is the completed turn.Notice I've left a thin rim for the lid to sit on. I'm going to make this a set in lid:

Next, I cut a small blank out of some scrap red oak and mounted it on the lathe. This became the lid for the box and since it was a thick piece of wood, I was able to cut the knob out of this blank without having to laminate another piece of wood to it:

Here is a photo of the finished lid and the box together:

And this is the finish photo after I've oiled the lid:

Now that will hold a lot of M&Ms.

The photograph from above is a flower vase that I began before this box and it has a number of problems-oily finish, chewed up end grain. I'm going to come back tomorrow and fix those and see how this works out.

It's getting cold and I'm going to come it and warm up a bit.

See you tomorrow.


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