End grain hollow form advice needed.

[Dan Forman]

I'm doing a green birch hollow form, about 4.5" by 4.5", and I think I have left it too thin for returning, at about 5/16 to 3/8" thick. I know end grain turnings don't warp to the same extent that side grain does, but do you think there is room enough to twice turn this One? It's still on the lathe, covered with a plastic bag so that I can go ahead and turn it to finish green if that's the only way to go. Here are a couple of pics, the chuck is a OneWay Talon for size reference. It's a nice chunk of wood, so I don't want to lose it, would rather twice turn if possible.

http://i98.photobucket.com/albums/l279/T-Caster/DSC_1090-1.jpg (http://s98.photobucket.com/user/T-Caster/media/DSC_1090-1.jpg.html)

http://i98.photobucket.com/albums/l279/T-Caster/DSC_1092.jpg (http://s98.photobucket.com/user/T-Caster/media/DSC_1092.jpg.html)

Thanks,

Dan

[John Keeton]

Dan, I don't get much opportunity to turn birch, but my limited experience with green endgrain turning would suggest you are OK on this one. It may be close, but I think you will have enough to true up the piece.

As a side note, this is a form I want to experiment with soon - lots of possibilities. Nice piece, and you are right, nice wood, too!

[Brian Ashton]

Sand it to finished quality (wet sand to 600 or so) then if it warps too much that it can't be remounted and turned you still may have a good piece. If it doesn't warp to much then you can remount and refine... it's kinda a crap shoot at this point to see what it will do.

[Joseph M Lary]

Dan,
I turn a lot of Green wood hollow forms, I leave the tendon sand to finish, put it in a plastic bag tie it shut, put a hole in the bag at the opening and put in a air hose with aquarium pump inside form and dry it that way. When it is dry Ill put back on with the rubber chunkie and turn away the bottom. It can be hit and miss with some woods. Good luck.

[Hayes Rutherford]

Putting it back on the lathe at 5/16" doesn't sound like fun to me but after reading JK's reply, the thought of just truing up the outside and not putting a tool inside might work.

[Steve Schlumpf]

Dan - without seeing the entire form, I have no idea if there are any imperfections in the wood that might become problem areas while drying, but based on what I can see, you should not have any problems twice turning this piece.

I have turned many forms with a similar shape and have twice turned all of them. The real thing to be concerned with when it comes to drying is to make sure that the walls are a consistent thickness. If they are, then the piece may oval a bit on you but you should be able to true that up with no problem.

Looking forward to seeing this piece once it is finished! Have fun!

[Dan Forman]

Thanks for the replies.

John --- Hope you are right!

Brian - I guess I could do the outside sanding as you suggest, just to be safe.

Joseph --- Sounds like an interesting method. How long does it typically take to dry that way?

Hayes--- I hadn't thought of the chatter possibilities, but then I've only turned one other green end grain form, and did that all in one go. I've really only done few hollow forms, and never twice turned one. The inside still has some ridges, thought if I cleaned it up any more I might lose even more wall thickness, so left as is.

Steve --- This is from a crotch, there is a little feather at what is the top of the second picture, and a knot with pith on the lower, opposite side of the first picture. I'm hoping to avoid a "wrinkled" appearance in these areas, which is why I want to twice turn. Another consideration - if the knot cracks, I'd like to be able to fill it with epoxy and be able to turn enough away to clean it up. I'll post a pic of the other side with the knot later today.

Dan

[Dan Forman]

Ok, Here is the pic of the other side with the knot. I'll be surprised if this doesn't split and need some repair.

http://i98.photobucket.com/albums/l279/T-Caster/DSC_1096.jpg (http://s98.photobucket.com/user/T-Caster/media/DSC_1096.jpg.html)

Dan

[Wally Dickerman]

Dan, You've got a good start on a nice piece of wood. Form is right on. On an end grain turning there usually isn't much warping but 5/16 is very thin. When working on the upper portion of the piece you'll exerience a little chatter when hollowing. Hope you have a steady rest. If not, this piece might convince you that you need one.

Good luck

[Dan Forman]

Thanks Wally, I'll have time to make one before this dries.

Dan

[Thomas Canfield]

Dan,

I am seeing quite a bit of wood at the bottom with the larger than shoulder of the tenon and even outside the diameter at the hollow form. That will take longer to dry and probably increase checking. I would be inclined to remove some of the extra wood and possibly even use a hose clamp around the wood.

[Dan Forman]

Thanks Thomas, I'll clean it up.

Dan

[robert baccus]

Good advice above for sure. Another way--I do mostly green hollow forms--is to turn the piece to 10% thickness and wax the outside and bottom and put it on the shelf. Twenty years of this has convinced me that drying from the inside only pulls the wood together. The steady rest is good advice

[Joseph M Lary]

You can dry it down in about a week or two depends on how thin you go . It will even close small cracks. I have also put some Deft to seal the out side and used the pump with out the plastic bag.

[Bernie Weishapl]

Dan good advice from all. Myself I would finish it out and soak it with a oil finish. A lot of my end grain turnings I turn to finish and then soak with antique oil. I soak to till it won't take anymore. Surprisingly most all of them don't warp much or have any problems with cracks.

[Dan Forman]

Did another one tonight out of walnut.

http://i98.photobucket.com/albums/l279/T-Caster/DSC_1098.jpg (http://s98.photobucket.com/user/T-Caster/media/DSC_1098.jpg.html)

Is the amount left for the base on this one better? I do like to have a little room to work in for the final parting off. There is an inch and a half of tenon and waste, plus half an inch of thickness for the bottom of the form, so altogether two inches of wood. Will this cause problems? I could use a reverse jamb chuck and turn off the tenon and some of the waste to make a new tenon, which would lose about half of the current extra thickness down there.

Dan

[Dan Forman]

Good advice above for sure. Another way--I do mostly green hollow forms--is to turn the piece to 10% thickness and wax the outside and bottom and put it on the shelf. Twenty years of this has convinced me that drying from the inside only pulls the wood together. The steady rest is good advice

Robert --- By "bottom", do you mean the outside bottom or inside bottom of the form? Thanks,

Dan

[Dan Forman]

Dan good advice from all. Myself I would finish it out and soak it with a oil finish. A lot of my end grain turnings I turn to finish and then soak with antique oil. I soak to till it won't take anymore. Surprisingly most all of them don't warp much or have any problems with cracks.

Bernie --- Does that hold true when knots are present too? I did that with the other end grain forms I turned about a year ago, but they were pretty clear. I'm worried about the large knot with pith, so want to dry this one slowly.

Dan

Dan

[Brian Ashton]

Did another one tonight out of walnut.

http://i98.photobucket.com/albums/l279/T-Caster/DSC_1098.jpg (http://s98.photobucket.com/user/T-Caster/media/DSC_1098.jpg.html)

Is the amount left for the base on this one better? I do like to have a little room to work in for the final parting off. There is an inch and a half of tenon and waste, plus half an inch of thickness for the bottom of the form, so altogether two inches of wood. Will this cause problems? I could use a reverse jamb chuck and turn off the tenon and some of the waste to make a new tenon, which would lose about half of the current extra thickness down there.

Dan

So far the shape and everything is looking good!

[Faust M. Ruggiero]

Nice form, Dan. On the first example you showed, the one with the knot, I would have turned that to finish and made that knot thin enough not to crack. Also, separating it from the tenon will help keep the knot solid. The walnut form will dry nicely. DNA soak will bring the drying time to 6 weeks or less. I bag the form for a week or two after the one day soak. Having said that, I usually have a bunch drying naturally so I can choose what I feel like finishing. I rarely rush them any more.
faust

[robert baccus]

Actually Dan, I was refering to all the wood if waxing the exterior. Bottom. tenon, everything. Might want to remove the wax later from the tenon. Let's beat this one some more--good thread. We tend to think of wood as wood but It's like women. Tough, young, old, weak, ect. Birch is a very hard, close grained strong wood--all of which mean easy to split of bust. Opposite end of the scale from Aspen, Box Elder ect. Resembles the fruitwoods in this respect which to me means all precautions. I have very little problem with split ect but I try to never hurry drying. OBTW the shape and woods are top drawer for sure. Love the tulip shape. crotchy old forester

[Thomas Canfield]

Brian,

The amount of wood on the walnut at the tenon looks much better but still gives enough for support. The sharp angle at the bottom would probably be better left with a radius clean up when you do the clean up and turn off the tenon. The sharp corners and edges usually are called stress risers and more prone to cracks forming there (same thing happens with metals). Nice looking walnut piece.

[Dan Forman]

When I took the birch piece out to pare down the waste at the bottom, I found to my chagrin that a wide crack had started already at the mouth. I had to turn off about a half inch to get rid of it, which I think was detrimental to the form, but not necessarily fatal. It made it stubbier, and the opening became wider. It had been wrapped in brown paper, then placed in a heavy paper shopping bag on the basement floor, but it obviously wasn't enough. I gave the outside a coat of Anchor Seal, and will put it back in the bag and see what happens.

Dan