So now I have a greater appreciation for the Hollow form turners

[Brian Brown]

I tried to do another hollow form last Saturday. It was a piece of very curly eucalyptus. MC was 24 when I started, so it turned easily. I don't have a hollowing rig, just a termite tool and a Hunter #3 on a full swan neck. So hollowing isn't so easy when you can't see what you are doing. I was working through a 1" hole in the top. I managed to get the interior "hollow" but the side walls were uneven in thickness.

My questions are:

When rough turning green wood hollow forms, are they like green bowls; cut to 10% thickness, dry/warp and re-turn, or is there a different procedure?

When drying, do you bag them, wrap in newspaper, or something else?

What is the trick to hollowing without a captured system (I'm working with a MIDI and no budget)? I am worried about cutting through the side walls.

Are the uneven (sometimes less that 10%) areas of the side wall going to be more likely to crack?

I got this and another piece of eucalyptus a couple of weeks ago. I assume the blanks were a standard square block when cut, but since that time they warped and twisted tremendously. I assume they will still move a lot when drying, and I really hate to lose the wood, because it is beautiful and expensive. You can see how warped the blocks are in the pics.

[Steve Schlumpf]

Brian - I follow the same procedures as when roughing out a bowl - 10%. Sounds like the wood is going to want to move on you - if it does, it does.

Make sure you wrap the outside of the form in brown paper bag (keeping the entry hole clear so the inside gets air) once it has flash dried after coming out of the DNA bath.

I use a hollowing system and use the laser to gauge thickness - but without it you have to continuously check the wall thickness using calipers. It's a slow process - but welcome to hollow forms!

As far as problems with constant thickness when drying - it can cause cracking if everything is not the same. A lot depends on the wood and how much it wants to moves when drying.

Best of luck with this! Looking forward to seeing the photos!

[Bernie Weishapl]

On some I do the 10% thickness but on most I turn right to final finish. I try to get the walls to a consistant thickness, sand and then I soak it inside and out with Antique Oil. I find if I soak it till I can see it come from the inside out and then do the outside I don't have much moving or cracking at all.

[Wally Dickerman]

Wow Brian...that wood really does a lot of moving. Looks like some madrone I've had. Eucalyptus turns fairly weel when wet but gets nasty when it's dry. Looks like some really nice figured wood though.

10%?...with wood that moves like yours does, yes. At least. With more stable wood I do a bit less than 10% on face grain and a lot less on end grain. End grain moves, but in an equal amount all around. Side grain moves more because it's half end and half side grain. Side grain moves more. Don't leave the bottom area too heavy though.

The real solution to wood that is that unstable is boiling. When I get madrone burl it's been boiled. Then it's very stable. If not boiled it's the most unstable wood in North America. There is a good article on boiling on Steve Russell's site. The best way to do it is to rough turn the blank, then boil it. Very effective. I have a friend who turns around 300 salad bowls a year. He boils all of them. He has a SS tank and can boil a dozen rough turned bowls at a time.

For a lot of years, all I've done to protect rough turned pieces is to very liberally coat them in Johnson's paste wax. If the wood is very wet or is a wood that's prone to cracking, such as fruit wood, I'll also brown bag it for a few weeks. Right now I have at least 50 rough turned HF's in my shop drying. All are waxed and none are cracked. And as you know, I live in hot, dry Arizona. (72 deg. today). Anchorseal works very well but the wood drys a bit more slowly.

As far as uneven side walls cracking, unless there a lot of difference it shouldn't matter. Depends on the wood though. Some woods are a lot more prone to crack than others.

When you turn HF's, you need to constantly measure. You need good calipers. The figure 8's will do fairly well unless you're going for really thin. If thin is what you want, expect to lose a few. As they say, when the dia. of the inside equals the dia. of the outside...you've lost it.:)

Wally

[Curt Fuller]

Brian, I don't have a captured system but I've used one a few times at our turning club. The biggest difference I've noticed in comparison to hand hollowing is that the captured system keeps the tool at a consistent angle to the wood. That prevents most if not all of the grabs and jerks from you get when hand hollowing. So you can concentrate more on light cuts when you're getting close to your final thickness and not have to worry so much about getting a catch and blowing the wood up. But even with the laser guides, you can still have problems getting to that negative wall thickness Wally mentioned because as the contour of the interior changes the relationship between the laser and the portion of the cutter that's doing the cutting changes and the laser needs to be adjusted. Measuring with a good caliper is still pretty important.

BTW, is that piece of Eucalytus from MacBeaths in SLC? I saw a bin of blanks almost identical to those the other day while there.

[Brian Brown]

Wally,

I have been reading a lot about boiling recently. I think the theory must be that when you boil, the water in the wood cells vaporizes, rupturing the cell wall, thus giving the water a better more efficient escape route. Is this right or wrong? If it is right, does this change the look or character of the wood? When the wood is finally stable, will it have moved just as much as with other drying processes? I have also heard that boiling will cause the color in the wood to "Homogenize", similar to the process of steaming walnut. Is this only on the outside, and will it turn away during the re-turn?

[Brian Brown]

BTW, is that piece of Eucalytus from MacBeaths in SLC? I saw a bin of blanks almost identical to those the other day while there.

Why yes, Curt. They just happen to be from MacBeaths. My wife loves to troll the bins there. For some strange reason, she missed these. A rare event, but luckily I managed to find them. Anytime we got to CS, Woodcraft, MacBeaths, or most other lumber yards, they roll out the red carpet for my wife. They really cater to her. They ignore me, because they know who is really going to buy the place out.

[Wally Dickerman]

Wally,

I have been reading a lot about boiling recently. I think the theory must be that when you boil, the water in the wood cells vaporizes, rupturing the cell wall, thus giving the water a better more efficient escape route. Is this right or wrong? If it is right, does this change the look or character of the wood? When the wood is finally stable, will it have moved just as much as with other drying processes? I have also heard that boiling will cause the color in the wood to "Homogenize", similar to the process of steaming walnut. Is this only on the outside, and will it turn away during the re-turn?

Brian, I have turned quite a lot of boiled madrone. Boiling doesn't seem to change the character or color of the wood. After boiling, the water looks like a molasses syrup. Madrone burl is just about my favorite wood to turn. When freshly rough turned bowls are boiled they move very little.

Green madrone, finish turned, can move an unbelievable amount. One time I turned a 12 inch, wet madrone blank. I turned it into a very thin walled bowl. When it dried it looked like a very wrinkled hospital bedpan. I kept it for a while until someone talked me out of it. Some turners such as Christian Burchard have featured the wrinkling effect on their pieces.

Wally

[David E Keller]

It's beautiful wood, Brian. I don't have any real experience with hollow forms, but I've had a run in with curly eucalyptus.

I bought a spindle blank when I first started turning pens. I cut the blank into pen blanks and proceeded to turn a pen and put the other blanks aside. In hindsight, the wood was pretty wet. The wood broke off of the tubes and curled up, and none of the other blanks was salvageable... Some of them almost curled to 90 degree angles.:eek::mad:

I hope that doesn't happen with that beautiful hollow form.