hollow vessel & splitting

Pick a piece without any pith in it. Then turn it so it has even wall thickness. Then put it in a paper bag or cardboard box with some shavings and let it dry slowly. Or you can blow air through it from the inside to get the moisture out of it quicker. Good luck OB in the Redneck riviera and what should be Lower Alabama

moyo wrote:

A general rule of thumb seems to be leave a wall thickness of about

10% of the diameter of the blank. This is large enough that there is sufficient material to retrue/shape it when dry yet th>Pick a piece without any pith in it. Then turn it so it has even wall

Good morning moyo! Every time I had the problem of "base splitting" that you mention, was because I got careless and left the sidewalls and bottom thicker then the average wall thickness. This is very easy to do, especially in the area of the bottom. Try for an even wall thickness throughout, being particularly careful in the problem area, and keep the piece cool and away from air movement for the first few days, and things should go better for you.

James Barley

The key with hollow forms (urns, vases, jug, whatever you want to call yours) is to get the walls and bottom THIN and to get them EVEN. Doing so minimizes the stresses generated by drying and just as importantly keeps the stresses uniform. I'm no great master (ask John Jordan who tried to teach me a little in Alaska) but even I've been able to turn a dozen or more pieces with the pith in place and have never had one crack yet.

As wood dries, it distorts. If it dries unevenly, the distortion is worse. The method OB O'Brien suggests, of turning to a thin wall before the wood loses much moisture usually prevents cracking, but it may lead to serious distortion. It is therefore usually reserved for natural edge bowls, where the distortion is not too noticeable, or may actually enhance the beauty of the bowl.

The method recommended by JEV, of turning to a wall thickness of 10% of diameter, is a compromise, intended to get the wood thin enough so it loses moisture evenly, so it does not crack, while leaving enough "meat" so it can still be turned round after it is through drying (and is stable.)

The technique offered by James Barley is ALWAYS good.

Okay, thanks for the info...one more question. Say a piece is 10in high and shaped like an upside down onion. The base being on the smaller end. What would consitute "thin"? Asuming that the pith is centered in the base?

Moyo

so don't bother with the 10% rule, just make it as thin and evn as possible?

Thin is in reference to wall and base thickness -- not the overall diameter of the outside of the object. For small objects I try to keep the wall and base thickness at 3/16" (4.5mm) or less and for large objects 1/4" (6mm) might be preferable. The really serious hollow form turners would sneer at these numbers and they routinely make even their large objects much thinner. With practice and the right equipment this is fine and certainly does impress viewers when you hand them a large object which seems to weight nothing -- I've never had the patience or the equipment to manage the super thin so I just stick to a thickness that works.

John McGaw wrote: (clip) I just stick to a thickness that works.(clip) ^^^^^^^^^^^^^ I have noticed that when a noted turner produces a bowl with somewhat heavier thickness, people, knowing that he could have gone thinner if he wanted to, judge it for its true qualities. If an unknown turner does the same thing, people assume that is the "best" he could do. I leave the walls at a thickness that pleases me, and is consistent with the use of the bowl and the character of the wood. Since I have no status yet, I guess I'll just have to wait until I am recognized before my heavier bowls command any respect. TIC

By analogy, just because a musician can play a piece very fast doesn't mean that he *should.* Sometimes a very small opening, or very thin walls are just a form of showing off.

I do believe that every turner should strive to do difficult turnings, just so he knows he can. And, after achieving a new level of success, it is not necessary to press that limit on every turning.

(I have used "he" above to mean "he or she.")

The analogy should be "just because a musician can play a piece very WELL ...". Either way, I don't agree with it. Would you consider a proficient

*anybody* to be showing off it they did what they did the best that they possibly could every time? I certainly wouldn't think it was showing off. They are being true to themselves, their talent and the art/craft of what they are doing. If the piece (woodturning or concerto), or perhaps more appropriately their interpretation of that piece at that time, requires of them to do something a bit differently (such as making a wall thinner OR thicker or a few bars of music more lagato) then that is their perogative. But to do something in a lesser manner to make other artisans feel better about it isn't a good thing for anybody involved.

I agree that we should be striving to stretch ourselves and it's not necessary to do so all the time. But, to deny that we *have* stretched and expanded to a point is bad. Once you achieve, it's a sad thing to pull back simply because "I don't want to" or because you might be accused of showing off. We all have our good days (weeks, months, years) and that is mostly unavoidable. So, we may not be able to do this month what we've been able to do all this past year. But that doesn't mean we shouldn't strive to get back to that level with each attempt. Sometimes it just takes small steps to get there again. No problem with that.

I don't begrudge those of greater skill than I and for them showing it with every piece. I'm glad that they did. I show my best efforts everytime. They are not the level of everyone else and not where I want to be tomorrow. I will improve.

It's not necessarily the result or process that matters. It's the intent behind it.

- Andrew

Leo & Andrew, To mangle some venerated woodturning maxims:

"Thin is More, or is it Less"

'Out of Reach' or 'High Shelf' art is just a bowl placed so high you can't judge its weight.

"In matters of artcraft there is no disputing taste" Don'tcha Believe it! "Re degustibus est no disputum" don'tchum believium!

"In turning thin walls, a man's reach often exceeds his grasp" (Probably there's a greek word for it, but the only words I know are vulgar ones I learned from sponge divers.)

'Age quo Ages' (do what you are doing, if it suits you)

"Excess Legato leads to a fortissimo catchio"

It's very late. Do I make myself clear? Arch

Fortiter,