hollowing question

Debbie

In my opinion, which is of value only to me...

I would go from log to finished piece in one go. I have never twice turned a hollow form.

I know that some do - Simon Levy of Tennessee does. John Jordan, also of Tennessee, does all of his pieces in one go at the lathe. I subscribe to the John Jordan idea that if you understand the properties of wood and what it will do and how it does it, then you can (sort of) control the outcome. Joh recently put out a DVD that is quite informative on the subject.

Take care

Ray Sandusky Brentwood, TN

===>Well, Debbie, since you opened the door by asking for opinions . . . ! My suggestion is to use LDD on green wood and then you don't have to worry about waiting for drying or have to finish it in one go. Since all the big guns are into visual media production, I have given some thought into producing "the" definitive LDD VHS tape or a CD. The problem is how to make a video tape of a chunk of wood sitting in a soap solution exciting to turners ("turn" them on, you might say)! Maybe scantily clad models of either sex (buyers choice) sharing a tub of LDD with the wood? That might give me a toehold in JJ's market base!*G*

Leif

Debbie,

I just finished a hollow turning out of green cherry. Unfortunately, as it dried, the base DID warp a bit so the piece rocked on the table. The owner has given it back to me to flatten out the base again. Their comment was that they didnt want folks to see it rock and think poorly of the designer. Thanks MOM! LOL

Leif, I have been away from the group for quite a while, but it is nice to see you are still here pushing LDD. I guess some things never change. Thank goodness. As to the models in the hot tub with the LDD, I cant help but picture the scene from 'Back to School' with Rodney Dangerfield in the tub with the ladies while wearing a mask and snorkel. I keep picturing bowl blanks floating in there too!

Bob

You must make allowances for the bottom warping because it will always do that.

First, the bottom must not be flat. It needs to be hollowed so that the piece sits on a thin rim of wood. Then, you need to flatten that rim after the piece quits moving. Turn the piece thin and let it sit for several days. Then there are several things you can do with the bottom.

You can glue a piece of sandpaper to a flat surface and sand the bottom rim flat by rotating and rubbing the piece on the sandpaper. Low tech but it works just fine.

Or you can reverse chuck it and re-turn the bottom rim. Reversing it can most easily be done using a vacuum chuck but since you are turning only a small amount of wood (the narrow rim) you can also just try taping the piece to some sort of a home made jam chuck.

Better yet, you can also just hold it against a jam chuck with the tail stock and use a piece of scrap at the tailstock end so that it doesn't make a hole. BTW, I'd use a small scraper on the rim or use a skew as a scraper. You aren't taking off much wood and it would be a shame to screw it up now.

Hope this helps. Bill

Bill,

The bottom was a small decorative ring around the bottom that came from to close to the original pith. I hollow all of my bottoms as I find a bottom with small details much more interesting than a simple plain one.

I will be reverse turning it as it warped enough to make the sandpaper method way to time consuming.

Bob

Hi Deb

Why don't you try to get the hang of it first by rough turning some green wood and set them aside to dry, then do some finished shape and thickness turning, by that time you'll have more experience and you can then finnish turn your dry ones, and decide then the how or what you like best. Just my way of looking at it.

Have fun and take care Leo Van Der Loo

Debbie wrote:

I'd like to make a plug for purely vertical section on the bottom rim. Even for the interrupted-edge stuff we turn green, it's a good way to avoid that thicker-thinner look on the bottom edges while still allowing the easier sandpaper adjustment.

Something I have read about but never tried... Drying the rough turned object in a microwave.

I would do a search on the topic, rather then take my figures, but it's usually 2 minutes at defrost followed by a complete cool-down (12 hours?) then another 2 minutes. Repeat until dry (using weight or a pin tester)

Normally hollowed pieces are turned fairly thin, in which case microwaving is not just unnecessary, but ill-advised. You can go from steam to smoke _very_ quickly. Let 'em dry quietly rather than risk. It's a matter of a few days at most.

I tried to dry a nice piece of maple in the kitchen microwave. Just a little at a time. Well I got it going too fast, and smoke started coming out of the end of the wood. Both ends. I quickly put it int the sink and covered it with water. The smoke was still coming out the ends. It was smoldering inside. By now the smoke is thick enough to set the smoke detercor off, and thick enough to make me concerened for the 4 cockatiels in the house. So I carried their cages outside. The wood is still smoking, but I was able to finally carry it outside and watch it burn to ashes in the driveway.

So when the wife comes home and sees the tiels on the front porch she knows I've been up to something. I said "Honey, lets go get a new microwave tonight." She said "Were you trying to dry your shoes again?" (That is another story that ranks right up there with drying wool socks).

My advise is buy an old microwave, use it outside, and never set it more than 6 minutes. But if you do it in the house use an aromatic wood. Maple may taste good on pancakes but it sure stinks as a smoking wood. Ricky

what power settings did you use for the microwave?

I've done a few pieces in the microwave but these were genearlly roughed out bowls. I start out at about 30% power (about the setting you would use for defrosting food) for a minute and check. If it is only warm I let it cool then increase the time maybe to 2 minutes. I never increase the power only the time.

You don't want it to become hot.

After several heat>>Normally hollowed pieces are turned fairly thin, in which case microwaving

There's the rub. 30% is not 30% by power, but by time. In the most insulated portion of your piece, or where you have something with high density like a knot, you can still light 'em. Mine seems to be about 15-20 seconds at 30%, followed by 30-45 of fan only.

Suppose if yours were to operate on shorter power times, might work better.

William, When I played with microwave drying I used one second at high per ounce of weight. I would repeat this until it was almost too comfortable to hold (but not painful), no more than three repetitions. I would let it cool for 30 to 60 minutes and do up to another series of up to three repetitions on the same program. If they would fit, I would do this with the blank inside of a plastic bag that had a hole pierced in it. The idea was to hold hot moist air around the outside of the piece while it was hot to avoid too great a moisture gradient in the blank. When it came out after the third repetition I would put it in a dry bag and let the steam collect until it cooled. This allowed for a slower but more controlled removal of moisture. When I noticed that the piece was not getting as warm as it had been, indicating there was not as much moisture to heat up and I would soon be baking the wood, I stopped and paper bagged the piece a couple more months. Not an immediate gratification program but I did get several pieces of olive to stay together and eventually finish up round and smooth.

Good luck, YMMV. David

william kossack wrote:

I'll have to try that

David Wade wrote:

Thanks everyone for your suggestions. Sounds like what I need to do is just give it a try!!

Debbie