Black Walnut goes BOOM

[Tom Keen]

Im stumped.. Black Walnut is one of my favorite woods but for the life of me I cannot find the formula for working with it. I have blown up a bunch of walnut bowls. One morning I lost three good sized bowls. 1,2,3 boom, boom, boom. Being a manly kinda guy, I did not cry, I repressed and turned the lathe off for the day. But, my problem with walnut is making me crazy. I have the remains of a dozen mature walnuts that we harvested this winter.. I have a mountain of walnut waiting for me but Im afraid to jump into it.

Being very stubborn and still in some denial, I cut up a couple of large log butts and have a dozen blanks yesterday. Before I get into these, Id like some help (see, I can ask for help:) and maybe I can get a few bowls out them.

The problem:

I bet well over half of the rough bowls Ive turned have developed fatal cracks while drying. The checking is bad enough but I tend to get canyon sized cracks.. top to bottom. This morning,I found two that I roughed out a few weeks ago ruined. I soak my roughed out bowls in DNA. I leave the prescribed 10% thickness. Ive been patient about letting them dry. Maybe they dry to quickly in the DNA...I dont know.

If Im fortunate and the bowls have survived the drying process, Im batting about .500 on the lathe. The tend to detonate (spectacularly). I know Ive caused a couple of these, but some just seem to let go. On inspection there seemed to be hair line cracks along the growth rings.

Any suggestions?

tia,
Tom

[Bob Hallowell]

Tom,
I don't know what to say I have turned a few bowls from walnut and they have all turned out great. I am driving down 2 hours to in 2 weeks to pick me up a load of walnut. I guy I work with was givien premission to cut up a bunch of left overs form some selct timbering for fire wood. I told him not to run his chainsaw til I came down or me and him are going to have some words, jeesh walnut for firewood!:D

Bob

[Reed Gray]

I have found walnut to be one of the easier woods to dry, being stable, and with little movement. You could be drying it too fast. Most of the time when I have a drying bowl crack on me, it is because of cracks that were already there. If you can see any, then turn them out (almost 100% success rate) or glue them up (perhaps 50% success rate). Are you having catches that blow up the bowls? Some times the cracks are almost invisible and even a small catch can cause a bowl to split.
robo hippy

[steven carter]

Tom,

Just wondering if all the blanks that have blown up are from the same tree or from different trees? A friend gave me a cherry log, and one side of the tree had an almost invisible half moon crack that ran clear through the log and that side of the log was completely unusable. I don't live that far from you, If you like I could try to turn a piece. My sister lives in Centerville Ohio. Just let me know.

Steve

[Mark Pruitt]

"Hairline cracks along the growth rings"? Could that be wind shake? If so, I'm not sure you'll get anything out of it. The good news is, if it's wind shake causing the blowups, it's no fault of your own and you just need better timber. I'm no expert in identifying wind shake but your description combined with the problem makes me wonder.

[Frank Kobilsek]

Tom,

My experience says that regardless of drying method DNA, Bag and await or Anchorseal and wait, inconsistent wall thickness of the rough blank will cause more cracks than anything else I might do. On the other hand, maybe further study of your blanks will show the crack was already there and you just find it late in the process.

Regardless wear your protective equipment faithfully. This just may be Gods way of teaching you good safety gear habits. Later you can be the super productive turner.

Frank

[Bernie Weishapl]

If it is from the same tree it could be wind shake. I got a bunch of bowl blanks from a downed walnut tree and got a half dozen lidded boxes is all. All the bowl blanks just cracked all over and were not turnable.

[Ken Milhinch]

Tom,
I am an absolute beginner, so I have no capacity to give advice to anyone, but something my instructor at a recent class told me may be worth passing on. He suggests placing a green bowl in the freezer for 24 hours, then in a refrigerator for 14 days. I tried this with a bowl I made under his guidance, and it worked. Hardly any movement at all. Success rates will probably vary depending on the type of timber.
Sorry if I am stating the obvious here, but at the moment, everything is new to me.
Of course this doesn't help with your "explosions" either.

[Shane Whitlock]

Sounds like ring shake to me too ... A couple months back I paid good money for a huge walnut trunk, about 10 feet long and 3 ft diameter at the crotch. I got some beautiful blanks out of the bottom half but the top half is full of wind shake. The only luck I have had with them is to keep turning until they are gone. Start out with a 16 inch bowl and end up with an 8 :(

[Jonathon Spafford]

Pardon my ignorance, but what is wind shake??

How about stabilizing the piece... there is a place around where I live that will take pieces and inject them with epoxy... if you get clear epoxy it will look like normal wood, but will be basically plastic! I don't know much about it and have never done it with wood that I have, but lots of guys I know have tried it... might be an option!

[Jude Kingery]

Tom, I'd agree with Reed & Frank, might be drying too rapidly to produce the hairline fractures like that. Might take up to a year or so to dry, use the anchor seal (or I just use parafin on the end grain) and let it dry real slowly. Then it should be easy to turn without blowing up on you, hope so anyway! Best of luck to you! Jude

[William Bachtel]

I wood try anchor sealing a ruffed out blank, on all sides. Store in cool not to dry an area. Lots of things can happen when drying wood. You proably have more than one thing going wrong here. Material, drying area, method of operation, all play into it., the tree could have been cut when the sap run was over, hence lots of water in the tree, hence more water to lose and more defect to deal with. If you can cut trees in the winter or late fall, never in the spring sap run.

[Patrick Taylor]

This may be way too obvious, but are you careful to keep a uniform wall thickness on the roughed blanks? That makes a big difference.

[Reed Gray]

Ring shake or wind shake are cracks that run along the growth rings, rather than radiating out from the center. I have been told that a tree that is growing out in the middle of a field will have more of this than a tree that is in a forest.
robo hippy

[TYLER WOOD]

WOW, problems with turning walnut? It's my dream wood. Sands well turns well, great looking. The only blow up I had was turning a hollow form and allowed the outside diameter to get larger than the inside. Other than that, it's been a dream. Sorry for your loos, but I'm at a loss for information for you.

[Tom Keen]

This a great forum! I appreciate the advice. Ive been working through my pile of blanks, trying to pay attention to what is going on with the wood. Things Im doing so far:

Refreshed my DNA.
Trying to get a uniform wall thickness and Im leaving the walls a little thicker than I have been.
Turning out cracks out when I can. When I cant, Im saturating them with CA.
Instead of cutting the log right down the center, Im cutting an inch or two out of the center of the log, trying to cut as much wood away from the center/pith of the blank as seems reasonable.
Im also alternating what orientation of the inside/outside of the bowl. Somtimes the sapwood side, sometimes the heartwood side to see if this makes a differenceI think you guys are right about wind shake. The wood Im using is coming from mature, large trees that grew in the open vs ones that have been protected by the woods (taller, straighter, less horizontal growth). They tend to have a lot more defects. The good stuff that came from the better quality logs Ive been holding back until I felt more confidant with my skills.

Thanks again, Ill post a few pictures of my progress.

Tom

[Burt Alcantara]

Tom,
I have black walnut from about 3 different sources. All of the wood is dry and has been left out in the open for indefinite periods.

Most of the logs had cracks but I sealed them when I got home. I've carefully sliced them with the chainsaw cutting down to uncracked wood. Well, at least to my eye. Got them on the bandsaw to shape. Still no evidence of cracking. Put them on the lathe and violent explosions. So far, not one from any of the logs has survived turning. Some hit me, the ceiling, went out the door, broke in half, broke into shards.

All of this happened before the bowl got anywhere near a "10%" thickness. I still have a large supply but will hold off until my skills improve. Could be me for all I know.

Burt