Hollow Forms

[Bernie Weishapl]

I have a question on turning Hollow Forms. When turning HF's out of green wood how far do you rough them down before you put them up to dry? Do you treat them kinda like bowls and leave the walls 10% of the thickness? Do you hollow the inside out to say 3/4" thick walls then DNA it and then let it dry? The ones I have done thus far has been dry wood. The one I did out of ash from green to finish about the only thing that didn't crack and split was the walnut collar I put on it because it was kiln dried wood. Any advice would be appreciate. Thanks.

[Ken Fitzgerald]

Bernie,

I pm'd Travis Stinson with this very question. He stated with wet wood he treats it like a bowl. Rough's it out; DNAs it and then let's it dry and finish turns.

[Mike Turkley]

A timely post Bernie as I want to know the same thing. I have three hollow forms roughed out so far with two placed in a paper bag with shavings. The other one went into DNA as a test. It's been a week on the DNA one and so far it's holding up well. All were turned about 3/4" to 1" thick walls and about 5 to 6" in diameter.

MikeT

[Jeff Moffett]

I've never turned a hollow form, but I saw a John Jordan demo last year at my club meeting. As I recall, he said he turns all of his hollow forms from beginning to end in one session. As he's roughing one out, he constantly tweaks the orientation between centers in hopes that any movement will be fairly uniform.

[John Hart]

3/4" Roughout sounds about like what I do.....that is, when I go through the drying process. I'll turn green all the way...but usually with warped results later down the road.

[Neal Addy]

Same here. Turn 'em from green to finish in one session most of the time.

If I'm really concerned about a particular wood moving or cracking I'll rough hollow it to 3/4" or so and boil it in water for about 1 to 1.5 hrs. Set it on a shelf for a week or two and finish turning. Most of the time this stops any movement. My latest Cocobola HF got this treatment and it worked pretty well. But even it developed a small check after final turning.

Some woods refuse to behave no matter what you do.

[Keith Burns]

Bernie, for DNA'ed i go between 3/8" and 3/4" depending on the size.

[Jeff Myers]

Bernie,
I've only turned a few recently and they were out of very wet Cherry,
I turned to 3/4" and dna'd for 24-48 hours and wrapped in paper to dry,,,
didn't work out for me at all,,,each one cracked terribly and quickly went
into the burn pile. Might be that Cherry is more prone to severe checking, i don't know...i've got 3 Maple HF's drying now after a DNA bath and haven't unwrapped yet to see how they're doing,,,been weighing them
daily and they're still losing weight so aren't dry yet.
got my fingers crossed,,,if these crack too,,,it's either too dry in my basement maybe since it's winter time or maybe need more paper to wrap them in,,,currently using two sheets of newspaper.
I sure don't have the answers,,,if these latest crack, i'll turn to finish and
see what happens then.

[Brian McInturff]

I've only done a few HF's but I turn to finishusually trying to keep close to uniform thickness throughout the whole piece. The only thing different I do is soak it several times in BLO usually within about 20 minutes of turning. But, most of mine are spalted and my understanding from the other day from George T. is spalting is a little more forgiving. I also sand at a higher speed purposely trying to generate a little heat to draw out some moisture. For me it's all experimenting but for the most part I've had pretty good results.
Brian

[Jim Ketron]

I will go with a 1/2" wall thickness on most of my rouged out end grain hollow forms depending on how large the piece is. most of the time you will not get the warp like on bowls with end grain hollow forms. Now if I do a side grain I usualy go with a 3/4" wall thickness still not as much movement as with bowls but more movement than an endgrain hollow form.
Jim

[Bernie Weishapl]

Thanks everyone for the info. I kinda had a hunch that was what was needed. I am going to see if I can get some time with the captured HF tool I got from Randy. Boy that thing is stout and should last a good long time. Thanks again.

[Travis Stinson]

Yup, rough them around 1/2" or so and do the DNA routine. You won't have the warping issues as bad with a HF compared to bowl, and will lessen the chances of cracking by roughing them thinner.

[Darrell Feltmate]

I like to turn to finish in one go for a hollow form. Orient the grain so it is perpendicular to the ground when finished. Then the warp will elongate the form uniformly and parallel to the ground so as not to distort the piece. Vases, being endgrain, tend to dry without much visable distortion. Make sure to turn with a uniform wall no thicker than 1/4". There is a tutorial on my web site.

[Bob Opsitos]

Start to finish with endgrain forms, not enough movement to notice.

Side grain forms move enough that I notice and object to it, so I rough to 10% thickness, soak in alcolhol, re-turn and finish.

Bob

[Jim Becker]

Like Bob, I turn end-grain hollow forms to finish. (I rarely do a hollow form that isn't end-grain orientation) If I need to walk away for awhile or overnight, I wrap the thing in plastic...still mounted to the lathe...to reduce any movement issues and also leave enough material to re-true in the next session.