what to do with the pith???

[Bill Wilcox]

I have just finished my first hollow form vessel out of "green" Black Walnut (with help from Jeff Nicol). I am putting it into a bag with some shavings and sealing the rim with wax. The piece is approx 1/4" thickness and the tenon is still on.
My question: If the tenon is left on the pith is still there. Should I drill the pith out and fill it after it has dried? Or do I leave it until the piece is dried then drill and fill the hole.
Thanks,
Bill Wilcox

[Robert McGowen]

I will be interested in reading what others have to say, as I do not turn this way very much.

In my opinion, if you left it with 1/4" walls and it moves at all when drying, I don't think that you left enough wood to turn it again. Therefore, leaving the tenon on it now is kind of pointless. The thickness of the tenon and the thinness of the walls seems like it would promote cracking. I would finish off the bottom, seal any pith area with CA, and just hope for the best.

[Mike Minto]

I will be interested in reading what others have to say, as I do not turn this way very much.

In my opinion, if you left it with 1/4" walls and it moves at all when drying, I don't think that you left enough wood to turn it again. Therefore, leaving the tenon on it now is kind of pointless. The thickness of the tenon and the thinness of the walls seems like it would promote cracking. I would finish off the bottom, seal any pith area with CA, and just hope for the best.

Bill, I'm kinda in line with Robert's comments on this one. You'll probably not have enough 'meat' on the vase once it starts to go oval on you; I'd suggest leaving more wood next time, say 3/4" or so. Also, I've started (on someone's advice, I forget who) cutting the tenon off my hollow forms, and re-fitting a glue block when 'returning' to the blank to avoid that difference in thickness and greater risk of cracking. Who knows, as this one dries and moves, it may enhance the form and all you'll have to do is sand & finish it. Good luck, post a pic. ;)

[Steve Schlumpf]

Bill - I agree with Robert and Mike - you didn't state how big the HF is but 1/4" wall thickness is considered finished by many and most likely not enough wood left to finish turn even if you wanted. At this point - I also agree with getting rid of the tenon in order to even out the thickness of the form while drying. I would keep an eye on it and if the pith area starts cracking - and it probably will - then I would CA it as needed.

Looking forward to seeing your hollow form when it is finished!

[Bill Wilcox]

The piece is 6" tall and maybe 5" in diameter at the widest point. The opening is approx 3" dia at the top. I made this into a lidded vessel and still have to rough turn the top which is 6" at where the bottom will fit on top of the vessel and tapers to the top which has a 2" top tenon. the top (lid) is approx 4" tall. I was planning to finish turn the whole piece to 1/8-3/16" thickness.

[Bernie Weishapl]

Bill I have to agree with the rest. Most of my HF's finished are 3/8" to 1/4" thick. I remove the tenon and soak the pith and bottom with thin CA. If you are going to have to let it dry with the tenon on so you put it back on the lathe to finish and fit the lid then I would drill out the pith and plug it because the CA won't soak in that deep to keep it from cracking.

[Tim Rinehart]

One of the very experienced turners in our clubs showed me something recently that he does...

In situations like yours, with pith in the tenon and waiting for it to dry, put a hose clamp around it and keep tightening a little each day as it drys, and you have better luck in preventing a crack that will ruin your base.

The comments about amount of stock you have left on are right on though, you need to leave enough stock to come back and cut, rule of thumb about 10% of diameter for thickness of wall, and be as consistent with thickness as you can to avoid differential drying that causes cracks, even with no pith involved.

Good luck...let us know how it goes..I've not tried this tip out yet, but it is sound and comes from a turner with more experience than most of us.

[Jerry Marcantel]

Can someone please tell me what pith is...... I think it's the soft cottony stuff that's at the very heart of some woods, but I'm not sure..... Jerry (in Tucson)

[alex carey]

http://www.hoganhardwoods.com/hogan/images/art/logcross_section.gif

center of the wood.