Hollow form questions

[Lawrence Tarnoff]

I'm about to sink further into the vortex and try my hand at hollow forms. I have a couple of newbie questions:

Do you usually work wet or dry wood?
If wet, do you turn to final thickness or follow a similar drying procedure as with bowls?
Grain orientation parallel to the ways?
Any particular cautions about hollowing end grain?


Thanks!

Larry

[Thom Sturgill]

I tend to turn dry wood as I like to know what the final shape will be and have some control over it. It is pretty much a requirement for boxes, though twice turning works. That said:

John Jordan says to turn green to final thickness to keep the fresh colors in the wood. He normally turns side grain orientation from what little I've seen. I took a one-day hands on with David Ellsworth and he also advocates turning green to final thickness and turning side grain. If turned thin enough, the pith can be left in as the wood will move enough to generally prevent cracking. I turned a side grain sphere out of Florida Rosewood with the pith centered and not cracking, but the form looks more like a football now.

Hollowing end grain provides gripping problems. Wet wood compresses more easily and thus tenons are not as stable. Also screws do not hold well. Some advocate for glue blocks in this situation. Depending on the orientation in regards to the pith, the piece may move in interesting ways or stay stable. I have a nice oak vase that went very oval and was lightly carved to make it look like an opening flower. Very organic effect, but not what I had envisioned when I started the turn.

[John Keeton]

If the idea of a small entry hole is of importance to you, then keep in mind that twice turning a piece that has been hollowed will result in a larger opening. On dry, the opening will need to be "trued up" and become larger when re-turned.

Most of my work involves multiple pieces, inset collars, etc., and dry wood is a necessity. Even then, one gets movement and must plan for it.

My experience with end grain hollowing has been good, and movement seems less. However, just from the nature of my work, a lot of it is face grain hollowing. Again, because I am using multiple pieces of wood, with glue ups. That can be done with end grain, but only cautiously, and with consideration for movement and differing directions of contraction/expansion.

[Jamie Donaldson]

I try to use wood that is not slinging wet, maybe damp would be a better selection for either grain orientation. It is virtually impossible to twice turn hollow forms for a number of reasons, all of which work against you.:rolleyes:

[Steve Schlumpf]

Not trying to go against the grain here but I twice turn all my hollow forms. I turn to a little less than 10% final thickness (probably closer to 7%), soak in DNA and then allow to dry for a couple of months. The grain orientation really depends on what it is I am trying to create, so really has no bearing on thickness when roughing out. The only caution I would offer really applies to turnings in general - regardless of grain orientation - and that is to keep the walls a consistent thickness.

Good luck!

[Kyle Iwamoto]

I also twice turn HFs. I put on a finial, so maybe it's more of a lidded box or urn, but movement would not be a good thing. Even dry woods move to some extent. Not much with end grain. I also would echo not turning something just cut down and slinging wet. A happy medium I guess.

The main reason I wanted to post, is try and search for the mulititudes of hollowing tool threads. I would reccomend just a couple tools to start off small, and see if it is something you want to. If you do want to hollow, my $0.02 would be to skip the largre hand held tools and get a laser captured rig from any of the manufacturers. They all work, and they all have limitations. Reading the threads will save you lots of money. I ran through the hand held tools (to save money) and got phsically beaten up. Ended up getting a captured rig anyways. The small hand held tools will still be useful in those areas that the captured rigs just cannot reach. The captured rigs take the physical strain out of the picture, and the laser takes the wall thickness guesswork out.

Enjoy your journey. It's all fun.

[Glen Blanchard]

I'm with Steve here. I always twice turn my hollow forms. I suppose I'm going to show my ignorance here but I never even thought about final turning a hollow form on the first turn. Bowls, yes. But not a hollow form. Just goes to show me how much I have to learn.

I used to soak in DNA for 24 hours before wrapping in newspaper to dry on the shelf, but recently tried the same sequence sans the DNA. Not only are they still not cracking but they are drying quicker than those I soaked in DNA. Here in Dallas at the beginning of summer they are drying in approx. 1 month.

I turn both end grain and side grain but currently I turn more side grain and I think I prefer it.

[Dale Miner]

I'm like Steve for the most part. I twice turn just about all of my cross grain hollow forms, and most of the end grain hollow forms. If the plan is to have a collar, finial, or lid, then twice turning is mandated. Dry wood in sizes large enough for 6" plus hollow forms is almost unobtainable, and even if the wood has been drying for 10 years or more, it will still move some after turning.

BTW, I twice turn all my boxes, whether from dry wood or from green. From dry, at least a week between turnings, from wet much longer.

[Scott Hackler]

For my regular hollow forms, I almost always turn green once...to final thickness and prefer end grain. End grain seems to minimize warping and the tenon is a bunch stronger while working on it! Then I do the Dna soak overnight and stick a rolled up paper towel in the opening and cover the exterior in thinned shellac. After a few weeks I do a final sanding and remove the tenon and apply finish. Keep in mind that I use a rather small opening and thin to less than 1/8" for small forms with no plan for piercing and 3/32ish for piercing candidates. Larger HFs will get the same unless I don't plan on piercing, then I will take them slightly thinner than 1/4"

If I make a box or urn or a vessel with multiple pieces and/or a lid, I will use dry wood or plan to "re-turn" the piece to minimize movement.

[robert baccus]

I do mostly vases & SW hollow forms. I twice turn and wax only the outside and lips and almost never lose a piece. A piece with a lot of compression wood and certain species will always be hard to save. By turning endgrain I get little warp and therefore turn down to less than 10% of dia. Remember you can always thin a piece from the outside, not just the inside. I tried Dna years ago but found it time and money wasteful with mediocre results. Wax is cheap(endseals). Hollow pieces well sealed on the outside only actually pull the wood fibers together and seldom split. The open inside allows quicker drying. We have a damp climate here--don't guarantee results in New Mexico. I essentially ignore grain orientation--If the curing is right the pith location seems to be easy. I do drop CA on the pith but usually CA the piece to a GB.

[Wally Dickerman]

I try to use wood that is not slinging wet, maybe damp would be a better selection for either grain orientation. It is virtually impossible to twice turn hollow forms for a number of reasons, all of which work against you.:rolleyes:

Jamie I don't understand your last sentence. Can you explain? I've twice turned hundreds of HF's. I don't want wood movement in my pieces.

[Jack Mincey]

I'm also with Steve and others on here in that I twice turn all my hollow forms and usually still keep the opening around 1 1/4". About 70 percent of my forms are end grain and I've never had a problem with a tenon not being held tight in #2 jaws of my strong hold for small forms and #4 jaws for my larger forms some 15" deep. I seldom ever use my bowl steady, but do have to use it on occasion for the second turning of the inside of the form.
Jack

[Dennis Ford]

I do both twice turned and once turned hollow forms, sometimes the warped appearance of a thin once turned piece is what I am looking for. Most of mine are turned cross grain and I use a faceplate for hollow forms except the small ones (< 7-8" tall).
Lots of ways to turn hollow forms, none are wrong as long as you "Don't bleed on the wood".

[Bill Boehme]

If you turn a side grain hollow form then twice turning can be a problem when truing up the interior (if you do that) because of interrupted cuts. A captive hollowing rig and light cuts will help, but there will still be some vibrations.

With end grin hollow forms, warping is not as significant. Steve Sinner rough turns his tall vase hollow forms then hangs them out to dry for a few months before final turning them.

I think it would depend on your intended design -- if a free form slightly oval shape is a positive contribution then turn the green wood to completion -- it it is intended to be a very formal shape like Steve Sinner's work then definitely twice turn.

As far as end grain holding large heavy and long pieces of green wood for turning hollow forms is concerned, I have never had a problem. Sometimes I use a heavy duty faceplate. The screws need to be the type with steep deep cutting threads for most secure holding. I also use long screws that are either #12 or #14 and either 2" or 2½" long depending on the size of the wood being held. I have never encountered a problem with screws working loose, but then I try to make gentle cuts. I don't like hogging the wood off especially if interrupted cutting is involved. I see that as a way of inviting problems.

If the wood is very solid, like mesquite, I will use a chuck with large jaws (Stronghold with #4 or Vicmarc with even larger jaws).

I also ought to mention that I start off by balancing the wood between centers, if possible, and then turn a mounting surface for a faceplate or a tenon for a chuck. A balanced load is always easier to turn and there is less vibration.