Why do I have these problems?

[Wade Lippman]

I just made two bowls, and they have some problems.
Both had wood blocks urethane glued to the bottoms. A screw was put in the wood block, and the screw was held by a chuck. I turned the outside first, and then did the inside. I have used that same system a dozen times before, and never had a problem. This time the bowl went off center between doing the inside and out, so the inside and outside are not concentric. That is shown on the top view of the willow bowl, where the left side is thicker than the right side. It is not much, but enough.

The aspen bowl cracked the day after I turned it; on each side of the end grain. The wood was about 4 months old and air-dried with the end grain sealed. I know that isn't normally long enough to be dry, but this wood is spalted and very porous; I "think" it was pretty dry. Why did it crack?

Two issues with the willow bowl. First, it took 2 cups of LBO! I took it outside and partly submerged it in a pan to get it all it. It now weighs over twice what it did before, and probably will still take more. Is that normal with willow? Did I do the right thing putting all that oil into it, or is LBO the wrong finish for willow?

The willow bowl is about 7" high. I only hollowed out about 5" of it because it was getting pretty difficult to work down there. Is that "acceptable" to the turning gods, or does leaving 2" of wood make it dilitantish junk? I could have gone an inch deeper, but I didn't have good control over the gouge and was afraid it would get away from me.

[Harvey M. Taylor]

Never heard of lbo. What is it? Max

[Chris Padilla]

LBO? You mean BLO - boiled linseed oil (which really isn't boiled, btw)?

Wood: a fickle medium!! Perfectly flat boards can turn into pretzels as well as perfectly rounds bowls can crack. It is all about internal stresses being relieved or incresed due to wood removal. You just never know...nature of the beast! :)

[Wade Lippman]

LBO? You mean BLO - boiled linseed oil (which really isn't boiled, btw)?

Wood: a fickle medium!! Perfectly flat boards can turn into pretzels as well as perfectly rounds bowls can crack. It is all about internal stresses being relieved or incresed due to wood removal. You just never know...nature of the beast! :)

Uh, yeah... BLO. I am a bit dyslexic; can't keep right and left straight.

So it just cracked because it needed to crack? Well, it was free wood.

[Scott Lux]

Leaving 2" of wood just makes it less likely to tip over.

But could the difference in thickness between the sides and the bottom could lead to cracking later?

[Tom Keen]

Stuff happens. Cant tell you how many bowls Ive done, stored and come back later and found them cracked. Worst was bone dry osage orange. This stuff was cut and aged for 15 to 20 years. I roughed out a few bowls and put them in my bedroom closet. I laid in bed and could hear "ping" "ping" as they cracked. Finally figured out it wasnt shrinkage/drying it was pressure as they picked up moisture and expanded. I ended up turning the rest of the bowls start to finish in one session.. never had anymore problems.

Your willow: I like to seal really porous wood with a sanding sealer before final finishing.

Best, Tom

[Nathan Hawkes]

Wood: a fickle medium!! Perfectly flat boards can turn into pretzels as well as perfectly rounds bowls can crack. It is all about internal stresses being relieved or incresed due to wood removal. You just never know...nature of the beast! :)





Sounds about right, for my albeit limited experience. I guess I'm a newbie still; I've turned a few dozen bowls now, maybe a little more. Anyway, I've had a few pieces end up as firewood that were perfect when roughed, then I opened a bag a couple months later and.........ddaM()t. The pieces that have been the worst at warping were spalted, if it makes you feel any better. I've given up on getting really upset when things break. I have a couple things that I've kept as reminders of what not to do... :D:D

[Steve Schlumpf]

Wade - without seeing how you were mounting the bowl blanks it is a little hard to figure out why things went off-center. My first thought would be that the 'screw' that was in the glue block and held by your chuck probably worked it's way loose a little bit because of a catch or aggressive cut. Wouldn't take much before the end of a 7" blank would wobble a bit.

Do you use a steady-rest? It would help keep the blank in place!

You made a good judgement call to quit hollowing when you did. As soon as you begin to feel that you don't have total control over your cutting tool - it's time to quit! No sense getting injured doing something you know is unsafe! You can always go back later and finish hollowing when you have a cutter that can safely reach past 5" .

As far as the Aspen bowl cracking - sure sounds like it probably had a lot of moisture left in it - especially if it was sealed for 4 months. Most likely it was the rapid loss of moisture once it had been turned that resulted in the cracks. It's one of those things that happens to all of us. If you have more of the Aspen that you want to turn - you may want to try the DNA soak and finish turn it in a month or so.

Hope that helps.

[Burt Alcantara]

Wade,
I've turned a lot of willow. After final sanding, while the piece is still on the lathe, I squirt BLO on the piece then rub it with my fingers. I turn the piece and continue like this until it has been covered with the oil. I only use enough to put a good wet layer on but not so much that it is dripping off.

Next, I turn the lathe on and using a paper towel, I apply pressure to the piece until the towel gets hot. If the BLO is flying off the piece then I put too much on.

This is followed with a similar procedure using a few coats of SealCoat (dewaxed shellac).

Two cups of BLO seems like a staggering amount. You only need enough to bring out the grain and give a little color. This is a good example of "less is more."

Burt