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Cottonwood: how to not get killed

Discussion in 'Woodturning Discussion Forum' started by Zach LaPerriere, Jul 22, 2016.

  1. Zach LaPerriere

    Zach LaPerriere

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    I've been seeing a lot of marginal to unsafe cottonwood turning around the internet, especially on Instagram, and especially with newer turners. So I thought to post a couple pictures, some thoughts, and hear what those more experienced than me have to say.

    A few days ago I got my hands on a massive cottonwood that floated up this way: almost 4 feet at the butt and over 80' to the first crotch. I took a few choice figured pieces, and as usual with cottonwood, there's a fair bit of ring shake.

    Today I prepped blanks and turned a half dozen rough bowls. I checked for shakes closely, and of course only turned what looked like sound wood. Early into roughing a crotch piece, I heard a flip-flip-flip sound. Here's what I found:

    IMG_0322.JPG
    With a bit of pulling, that chunk split clear off. That's a piece that could kill a person if you were in the way and unprepared.

    Onto the second troublesome bowl. This shake only turned up as I was roughing the interior. I had inspected the outside very closely before starting on the interior. I have good eyes, and I'm pretty sure nothing was visible until I got most of the way into the interior. Here you can see me pulling on the side of bowl to make the shake visible:

    IMG_0319.JPG

    So, obvious safety things:
    1. Inspect your cottonwood before turning and often while turning. Pay special attention to areas near the intersection of heartwood and sapwood
    2. Wear proper face and head protection. Safety glasses aren't enough. Face shield, and a helmet is a very good idea.
    3. Stand out of the line fire. If you don't know what that means, check out Robohippy's video on Youtube. Expect cottonwood to come apart!
    A fourth consideration: Cottonwood is horrible to turn. It tears-out more than any other common species that I know of. Sanding is also a bear. I would personally only turn cottonwood of exceptional grain.

    Anyone have more to add? I'd love to hear.
     
    odie and hockenbery like this.
  2. hockenbery

    hockenbery AAW Advisor Staff Member

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    Zach,
    Great advice. Wood with structural defects like ring shakes or bark inclusions can be extremely dangerous. Cut the connecting wood and a large piece becomes two with only one of them connected to the lathe. Black walnut seems to have ring shakes more often than other species.
    We need to inspect all blanks for defects before mounting and through the turning process.
    Al
     
  3. Justin Stephen

    Justin Stephen

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    Educational for me. I did not know that Cottonwood was a problem wood, but I've also never tried to turn it either.
     
  4. robo hippy

    robo hippy

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    I haven't turned much of it, in part because around here, it smells like some one threw up on it, and most of what I have seen is plain off white in color, the shade that sits and never sells. The stuff you show is really pretty.

    Being able to tell a piece has problems is pretty important. Over the years, I am very cautious about any black or dark lines that follow the growth rings because they tend to be ring shake, even if there isn't a visible gap, there frequently is weakness and they will crack after turning.

    Stand out of the line of fire at all times....

    robo hippy
     
    Zach LaPerriere likes this.
  5. Steve Worcester

    Steve Worcester Admin Emeritus

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    Down here, cottonwood is the massive tree your neighbor has and the next day it fell down on his house. The grow huge, and fast, but just too soft for my taste
     
    Zach LaPerriere likes this.
  6. Gretch Flo

    Gretch Flo

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    I am always looking for cotton wood crotches. Crotch figure seems to travel further than alot of other woods (say ash or box elder) so that there is more more volume of it within the bowl. Boring by itself but colored can be dramatic. Also the furriness in some parts accepts the dye asymmetrically. You certainly don't know how the dye will take to it leading to myriads of color and unique pieces. Am at work and can't attach picture. Some others are in my van for a craft show in a week, and I will photo some as i dig them out of the boxes.
    Bill-didn't you have a beautifully colored lipped bowl you've posted before that was cotton wood????. One tray I had, I kept for a couple of years before selling as a conversational piece at craft shows. Bear to finish/dye due to tear out and knots. But I was up to 24 animals I/interested people could visualize. Yes stinks but when drier , not so much. Box elder smalls like what I duded to remember from as ash tray of old cigarette butts. (not many people I work or associate with smoke.). Gretch
     
    Zach LaPerriere likes this.
  7. Gretch Flo

    Gretch Flo

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    Ring shakes I am finding in all kinds of woods. Carpathian walnut, (not so much in the black walnut gathered from my home and neighbors -have a ton of it!!!!), box elder, redbud, Kentucky coffee tree, honey locust. to name some, the onion burl that I mentioned a few months ago. Gretch
     
  8. Bill Boehme

    Bill Boehme Administrator Staff Member

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    Great tutorial on safe turning, Zach. I got a couple pieces of cottonwood a couple years ago and never turned it because it was too stinky. It didn't take too long before it started splitting in the hot Texas summer sun. I hauled one of them off to the dump. The other one was too heavy so it is still sitting on the driveway where the ants and termites are feasting on it.
     
  9. Zach LaPerriere

    Zach LaPerriere

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    I thought about this today some more while turning more cottonwood.

    I've been seeing a lot questionable turned wood (especially) on Instagram, mostly cottonwood, and much of it with obvious ring shake. What I realized is that these bowls show unsafe turning, but many of the sound bowls were also turned through unsafe practices—but I just can't see that those were turned in an unsafe manner.

    So: I think we all have a duty to educate those who don't know better or who should know better on safety.

    Thanks for the responses.

    Gretch makes some great points: there are many other species prone to ring shake. I've seen it in every species I turn, but cottonwood has about a 50% ringshake rate for me. Maybe Alaskan cottonwood is extra prone, I really don't know. I haven't turned black walnut, thanks for pointing that one out, Al. Important to know your species and be vigilant.

    Another point Gretch made that is very true: crotch figure goes far and wide in cottonwood. You can't really see it in the second picture I posted above, so here is that same bowl before turning the inside. Worth putting up with grain that tears, ring shake that made me cut the rim lower, and extra sanding that will be inevitable if it doesn't split more.

    13781879_1219776594725296_2959595799246330542_n.jpg

    So, if cottonwood does fall down on your neighbor's house as Steve said, it's well worth salvaging the big crotches! I also got some decent bird's eye from the recent cottonwood, but pictures don't really show it at the rough turned stage.
     
  10. John Torchick

    John Torchick

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    Ring shakes? New term for me. Please explain. Thanks.
     
  11. hockenbery

    hockenbery AAW Advisor Staff Member

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    These are separations of the wood around a growth ring.
    often called wind shakes and are caused by wind bending the tree.
    An inner growth ring separates so the outer ring wood can slide on it a little like a piston so the tree does not snap.
    They do not always go around the entire ring maybe 2/3 of it or 1/4 of it.
    The obvious danger is cutting a bowl blank from a half log with a wind shake in it.
    You turn away the wood tut is not split and there is nothing but air holding the two pieces of wood together.
     
  12. Bill Boehme

    Bill Boehme Administrator Staff Member

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  13. Gerald Lawrence

    Gerald Lawrence

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    Ring shake can also occur when the tree is felled. Usually having to do with how hard the tree lands and how prone that species is to having shakes.
     
  14. Gretch Flo

    Gretch Flo

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    I have a picture on the thread ( or are we in conversations now???)of onion burls
    WHAT IS THIS "CHERRY BURL"?????
    Discussion in 'Main Forum' started by Gretch Flo, Mar 9, 2016.

    Tags: Add Tags
     
  15. Gretch Flo

    Gretch Flo

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    Zack-That's going to be darned pretty. Be sure to post the final result!!!!! Gretch
     
  16. Bill Boehme

    Bill Boehme Administrator Staff Member

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    The term "thread" comes from its software programming structure. XenForo's aim is towards a user oriented terminology so "discussion" replaces "thread". I don't have a rational explanation of the reason why XenForo chose to replace "private message" with "conversation" other than wanting to be different.
     
  17. Gretch Flo

    Gretch Flo

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    "I have a picture on the thread ( or are we in conversations now???)
    The term "thread" comes from its software programming structure. XenForo's aim is towards a user oriented terminology so "discussion" replaces "thread". I don't have a rational explanation of the reason why XenForo chose to replace "private message" with "conversation" other than wanting to be different."

    MARKETING-so it's not plagiarized, gotta make something different. Gretch
     
  18. Gretch Flo

    Gretch Flo

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    Ring shakes. Just took. The first pictures are a large (11x5") . Kentucky coffee tree. While I have turned others with the rings, they were partial. The rings aren't perpendicular to the wall-they are oblique and so the glues real well and blends well. I spent 2 hours on the outside, saw the subtle ring, and decided to go for it. Then started turning the inside. . After 2" deep, discretion got the better part of valor. Keep this by the wood stove for? whatever reason-turned 2+ years ago. #1 pic is a further away view of the inside
    011 (640x360).jpg
    011 (640x360).jpg
    #2 Close up of shake that told me I should quit as it was going to join the outside ring shake.
    [​IMG]


    after drying by wood stove this is what happened to the outside
    #3 . 014 (640x360).jpg

    [​IMG]

    A 4th picture is of a nice natural edge crab apple turned completely (and I saw the faint ring shake) , and forgot to put in Al's box. I did see the faint ring shake
    when the outside was completed but didn't know how deep til I did the inside. Next day it looked looked this
    [​IMG]
     

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    Last edited: Jul 24, 2016
    Zach LaPerriere likes this.
  19. Gretch Flo

    Gretch Flo

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    sorry for all the pictures (#17) and tired of editing to no avail. you get the "picture" . Why can't I get this computer stuff???????When I think I finally "get it", they change the program. Grrrrr, Gretch
     
  20. Zach LaPerriere

    Zach LaPerriere

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    Thanks, will do, Gretch! And what a good picture of ring shake on the Kentucky coffee tree you posted. That looks from here to have developed during the drying, as you said. To my eye, it looks like drying related ringshake because the fibers are broken along the shake—whereas all the ring shake I've seen in green wood is smooth. Once split apart, you could easily mistake the ring shook surface for the smooth cambium layer of a tree after peeling bark.

    Just to clarify for anyone who hasn't seen ringshake: it is a separation parallel (along with) the growth rings. When ringshake is just beginning it's harder to see that normal cracks or checking that run perpendicular to the growth rings.

    So keep your eye out for even the smallest of a hairline crack along the growth ring, especially on species identified in this thread. Also be especially vigilant on trees that fell on hard ground or over other trees, as Al said. Same story with driftwood logs, as I've seen plenty of ringshake in logs I've pulled off the beach that presumably formed from logs hitting rocks hard in waves. I've also seen ringshake in rounds and lumber that was left to soak up too much water.

    Alright, that's the end of my safety talk!
     
  21. robo hippy

    robo hippy

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    Some times it is obvious due to clear separation, some times it is only a slightly darker line in the growth rings with no separation. Still a weakness, and flooding it with CA glue can help but doesn't make it 'safe'!

    robo hippy
     
  22. Owen Lowe

    Owen Lowe

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    Not absolutely sure, but I think this is what a friend calls “breaking a tree’s back”. When a tree is felled and allowed to hit the ground in a “Timmmmberrrrr” fashion the wood can crack internally from the forces. Gerald mentioned it above and I think this is what is shown here.

    I believe the forces first cracked the outside area of the tree perpendicular to the rings and then the crack found that going along the ring had less resistance until the energy dissipated...
     
  23. Pete Blair

    Pete Blair

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    IMG_2789.jpg Slightly off topic but. Just returned to the Great White North from a trip to Missoula MT and heard about some VERY large cottonwoods that had been cut a few weeks earlier. Unfortunately there was way too much checking and splitting for me to try to cut a few pieces to bring home. There were about 6 piles like I am standing in front of. The piece I am leaning against had been quartered! Must have been some big trees!
     
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  24. Gretch Flo

    Gretch Flo

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    Ring shakes were first apparent. The perpendicular happened? weeks later after I had given up. But chicken or the egg??? Gretch
     

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