|Project by Alin Dobra||posted 2268 days ago||1075 views||1 time favorited||5 comments|
Most people do not initially believe me when I tell them that I turned these two pieces (the last picture is a different bowl). They are nevertheless turned but some trickery is involved, as I will explain shortly.
First, both bowls (or platters more likely) are made from local live oak, which is plentiful in northern Florida where I live. These two came from a large forest that got cut down to make room for yet another building project. To get such an unbalanced piece, you have to start with unbalanced wood. Both bowls are made from large crotches. If you take a careful look at the grain pattern, you will notice the pith of the main trunk and the pith of a major branch. Since they were cutting so much wood in the forest I was mentioning, I took my chain saw and harvested about 15 crotches, just to make this kind of bowls.
If you want to turn such unbalanced pieces, you have to overcome a number of technical problems>
1. Unbalanced wood tends to fly from the lathe at large enough speeds or at least make the lathe walk across the room (even if bolted to the floor like mine). All in all it can be a scary experience even if it lasts only for 5 seconds (the time to stretch and stop the lathe). The first trick is to perfectly balance the wood on the lathe between centers. To do this, I position the wood between centers without tightening the tail stock so that the wood can move freely. The wood will promptly drop since one part is heavier. Then you move one of the centers upwards a little and repeat. I usually stop when it takes the wood more than 2 seconds to go from the highest to the lowest point. Then I start to turn and I make a perfectly flat bottom and a spigot for the face place (that gets mounted afterwards to continue turning).
2. Unbalanced wood has large gaps filled with air. When shaping both the outside and the inside, you simply cannot cut with the bevel since you immediately hit air and overshoot. What you have to do is describe, at an excruciatingly slow speed, a curve in the air without any support. You go from outside towards the inside for the outside of the bowl and from inside towards inside for the inside of the bowl. When you are done, you can use scraping cuts with the bowl gouge (which are far more controllable but inefficient at removing a lot of wood) or an actual scraper to smooth things up. You still get some tool marks which you have to send away.
3. Resist the temptation to get too close (or touch) the bowl when spinning. Since it is so unbalanced, it ill promptly take a part of the skin or at least hit you badly.
I am turning these bowls on a 16” Grizzly lathe. I do not recommend you using a smaller lathe.
The last thingsI want to mention is that the wood for first bowl sat on the ground a couple of months, time in which it got infested by the fungus that produced the nice coloration. Both bowls are oil finished and sanded to a silky finish.
-- -- Alin Dobra, Gainesville, Florida