YouTube vid

discussion of the niceties of turning on a bow, bungee or pole lathe.

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YouTube vid

Postby Robin Fawcett » Tue Jan 08, 2013 11:35 pm

http://www.youtube.com/watch?feature=endscreen&NR=1&v=7WX6QsRX4aA
What intrigued me about this was the number of wraps of cord this guy puts round his spindle - is it 8 or 10?
What does anyone think about this...
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Re: YouTube vid

Postby jrccaim » Wed Jan 09, 2013 5:57 am

) agree with you Bob, that is far too many wraps for my taste. Three is more than enough for me and I usually use two. But this is an excellent video to watch because ot goes from log to chair leg in steps. Excellent for beginners. But on that note, please let's look at some some stuff one might have missed. If you are an old hand this will be boring, so go read the next post :) I won't mind at all. Beginners, read on.

(1) A log is much too big to turn. You would be a lifetime turning a log down to a chair leg, even if your lathe could swing it. It would also be extremely wasteful of wood. A pole lathe simply cannot remove large amounts of wood. So first the Gallah Bodger, hereinafter G, spits the log into quarters. Could use a Froe. Could use a wedge. Could use a maul. He uses an axe. Fair enough. Warrior, use the weapon to hand. An axe will remove far, far, more wood in ten seconds than a pole lathe. For that matter see below.

(2) What G has done is to produce a pie-slice piece of wood, highly irregular. G uses a froe to sort of square up the wood. I say sort of because micrometer precision is useless. A froe will remove far, far more wood in ten seconds than a drawknife. G then resorts to his trusty shaving horse and drawknife. His object is to reduce the pie slice section to some approximation of a cylinder. Again: a drawknife (in a horse) will remove far, far, more wood in ten seconds than a pole lathe. What you want to do here, dear beginners, and my heart goes out to you because I too was a beginner once, is to make it roughly square, then shave off the corners so you've got an octagon and then shave off more so you have a 16-sided (hexadecagon?) figure. But remember, the closer you get it to cylinder the less you will have to do in the pole lathe and it will be much, much, faster. A drawknife is much, much faster than a pole lathe.

(3) At this point G has determined he's got it close enough to cylinder he finally goes to the pole lathe and the real turning begins. At this point I stop because I trust you have gotten my point. Regardless of the number of wraps and G is a real artist regardless of the number of wraps he uses! I think that this is so important that I will recap.

At each stage you have to remove different amounts of wood. A log clearly does not resemble a chair leg. So you must take off wood in stages. Each stage removes roughly ten times less than the previous stage. The progression is axe -> froe -> drawknife -> pole lathe. Once, just for fun, I took a vernier calliper to the shavings I was getting off my pole lathe. They came to about 0.1mm give or take 0.05 mm. Very tedious to turn big stuff to make a chair leg tenth of a mm at at a time. And at that, I skipped the spokeshave. A spokeshave will do about 0.2 mm shavings, so it you need to zero in on a diameter, it may be just the thing.
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