Wind Checks (Shakes / Ring Shakes)

[Rick Urban]

A few years ago a friend gave up woodturning. He was an experienced turner and had a chunk of wood spinning on his lathe. He was standing by the head stock. The tool he needed was on the other side of the tail stock on the bed of the lathe. He reached over to get it and the spinning blank experienced a spontaneous unscheduled disassembly. He suffered a serious injury to his facial structure in spite of wearing a face shield.

Yes. He recovered. Yes. He returned to turning. He is another, like myself, who has learned to Respect the "Kill Zone."

What caused the catastrophy? A wind check! A wind check is a crack that follows the growth rings. Its geometry is such that it is easy to think it is not much of a problem until you hollow that bowl far enough to remove the wood holding it together. Then... Unexpectedly... Boom!

I remember being introuced to wind checks after a few years of turning, but noone emphasized any special threat. And, besides, the term "check" just meant "tiny crack" to me. Some of them are dangerous!

 

[Tim Connell]

Here is a short article defining some of the terms and the causes of shake, checks and splits.

Contrary to many articles written by non scientists, shake is not caused by wind, but rather by bacteria in the clostridium genus.

Shakes, Checks and Splits in Dimension Lumber | SPIB Blog | Southern Pine Inspection Bureau

What is the difference between a shake, a check and a split? They are similar in that they all are separations lengthwise in the grain of the wood; however, each has a different origin and a different…

blog.spib.org

 

[Rick Urban]

Tim,

Thanks for that! And all these years I've been thinking "checks." Maybe I should edit the thread title.

 

[Brian Gustin]

Yep. and a funny thing about ring shake, it can be so subtle that you can't even see it until the spinning piece starts to come apart. One of the clues I have noticed often enough with pieces that come apart is to look for discolored rings, It isn't always ring shake, but often enough when it is there, the rings will be discolored compared to the rest of the log. (but not always) so I always will take a very close look if I see odd ring colorations in a piece I am working on to the point that I might even apply a coat of shellac or CA glue and see if it wicks into the log which usually will show up a crack that is otherwise invisible.

 

[robo hippy]

I am surprised at some of the wood I see at our club raffles. I know some delight in getting the nastiest piece of wood they can find and taking hours to turn a piece out of it. Me, I throw pieces like that into the wood stove. I don't want things that sit on the shelf, I want things that are used every day.

robo hippy

 

[hughie]

Luckily for me wind shake or whatever, I haven't seen much of it if any at all down here. In fact I find it only referred to or spoken about by my peers in North America.

 

[Brian Gustin]

Luckily for me wind shake or whatever, I haven't seen much of it if any at all down here. In fact I find it only referred to or spoken about by my peers in North America.

Makes me wonder if it isn't indeed some type of fungus or disease, perhaps in soil or environment, that is native to certain areas, and just hasn't crossed the ocean to Oz yet.

 

[hughie]

Makes me wonder if it isn't indeed some type of fungus or disease, perhaps in soil or environment, that is native to certain areas, and just hasn't crossed the ocean to Oz yet.

could well be, I have often wonered myself

 

[robo hippy]

I think wind/ring shake happens is 'because'. Probably a combination of factors, at least some times....

robo hippy

 

[Don Wattenhofer]

Here is a short article defining some of the terms and the causes of shake, checks and splits.

Contrary to many articles written by non scientists, shake is not caused by wind, but rather by bacteria in the clostridium genus.

Shakes, Checks and Splits in Dimension Lumber | SPIB Blog | Southern Pine Inspection Bureau

What is the difference between a shake, a check and a split? They are similar in that they all are separations lengthwise in the grain of the wood; however, each has a different origin and a different…

blog.spib.org

That is a great article that maybe should be referred to in the main discussion forum so that every check is not referred to as a crack. The article was referring to lumber so it should be noted that checking on an unmilled log or any extra thick piece like a turning blank will be much worse due to the larger distance moisture has to travel to get to an exposed surface.

 

[Kent Reisdorph]

I wasn't familiar with the concept of wind/ring shakes until this thread. The other day I cut into a large log that had been felled some years ago (before I moved here). I believe it is yellow popular. At any rate, I was surprised to see just how smooth the inside of the shake was.

 

[Jon Minerich]

Yesterday I was turning a bowl. Much like the wood in Kent’s photo, the bowl came apart right along a ring. i was out of the line of fire, but learned a good lesson. Some wood just belongs in the burn pile.

 

[Tom Albrecht]

Whatever the causes that started it in the first place, why would you mount a piece of wood with visible split or check on a wood lathe?

 

[Larry Mercier]

Whatever the causes that started it in the first place, why would you mount a piece of wood with visible split or check on a wood lathe?

Maybe I'm very lucky to always have enough blanks to be able to put a piece of wood that has a defect in the burn pile. One caveat: I only turn raffle or free wood so it is easy to decide to burn rather than turn

 

[hockenbery]

Yesterday I was turning a bowl. Much like the wood in Kent’s photo, the bowl came apart right along a ring. i was out of the line of fire, but learned a good lesson. Some wood just belongs in the burn pile.

Glad you were not hurt. Some ring shakes are hard to see.
I make it a habit to inspect blanks before turning and I stop during the turning process to look at the surface, shape, and any anomalies.

Tough to spot Ring shakes are easier to see as the surface gets smoother.

There have been a few I heard before seeing. Cutting over a shake makes a warning tick sound.

 

[robo hippy]

Maybe a side topic or diverging thread, but I see a lot of pieces of wood at our club raffle that I would toss straight into the burn pile. As I have gotten more 'experienced' with turning, I can spot ring shake better than when I first started. One old ash bowl was great for a couple of years, and then it split along one growth ring. Looking more closely at it, that ring was a slightly darker color. ALWAYS stand out of the line of fire!

robo hippy

 

[Gerald Lawrence]

Yesterday I was turning a bowl. Much like the wood in Kent’s photo, the bowl came apart right along a ring. i was out of the line of fire, but learned a good lesson. Some wood just belongs in the burn pile.

Glad you made it with only a scare. Too much wood down there to try that stuff.

 

[Jon Minerich]

Several good points were made for new or newer wood turners.

Some ring shake is tough to see. Hackberry also made an interesting point. The bowl did make a tic-tic sound when turning. I will remember that. Things were normal until I started getting the walls down to 3/8”. Obviously, I never got them thinner.

Gerald you are right. From now on, I will inspect each piece before turning. When in doubt, toss it out!

 

[Kent Reisdorph]

Whatever the causes that started it in the first place, why would you mount a piece of wood with visible split or check on a wood lathe?

In my case, it wasn't visible.

 

[Kent Reisdorph]

I turned this plate before I knew about the wind check. After it dried a bit, it was obvious.

Wind Check Plate

 

[Dean Center]

I agree with Al that ring shake can be hard to see on freshly cut wood. Sometimes, one growth ring just seems to catch your eye--maybe it's just a shade darker. When the wood dries, they're generally more obvious, but what fun is it to wait for dry wood to turn a bowl?

Our club members just parted out an elm 'tree'. The owners had cut it off about 10 feet from the ground 10 years ago, then decided the stump made a nice yard feature, and left it. The trunk sprouted and it's been sort of growing ever since. In any case, it had a lot of ring shake and when the wood split apart, in some places there was a thick carpet of black debris within the split. No mistaking the shake from this tree, you could slide a screwdriver into the space.