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working with different wood species

Discussion in 'Woodturning Discussion Forum' started by Karl Best, Jun 22, 2020.

  1. Karl Best

    Karl Best

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    The recent thread at https://www.aawforum.org/community/index.php?threads/rough-turned-bowls-cracking.16158/ included a couple of mentions of how different wood species can dry differently, and hints of how they should each be handled. Are there any books or web pages, etc. that go into more detail of how the different species dry, or perhaps even discussions of turning the different species? I've got a few books on wood identification (Baker, Porter, Meier), and several books on turning (Ellsworth, Raffan, etc.) and all of these have brief mentions of different species. But many of these are comments are simply along the lines of "great for turning"; such a comment may be interesting but it's not particularly useful.

    My particular example is that I've nearly exhausted my supply of oak from a fallen tree, and I'm next going to fell and chunk some nearly-dead ash trees (victims of the ash borer; I've got several of these). How should I expect ash to act differently on the lathe than oak? What different precautions should I take with regard to drying? And then when I go next to a walnut tree that I've got my eye on, how will that wood dry and work differently?

    Those are just the specific questions. Are there any resources that go into depth on multiple species?
     
  2. Kent Jaffrey

    Kent Jaffrey

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    A good quick free starting place you probably have already seen is the wood database https://www.wood-database.com/. There summaries are pretty good and they list the ratio between tangential and radial shrinkage which has a lot to do with how unevenly a bowl might shrink/warp.

    as far as the ash I’ve turned it seems to be a little more stable than the white oak I turned at about the same time so it warped less after rough turning. For turning the dried blanks I thought they are pretty similar in workability
     
    odie likes this.
  3. Mark Jundanian

    Mark Jundanian

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    If you're looking for a book, I suggest "Understanding Wood" by R. Bruce Hoadley.
     
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  4. Dave Bunge

    Dave Bunge

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    "The Wood Handbook: Wood as an Engineering Material" by the US Forest Products Lab is an excellent resource. Lots of info on general properties and characteristics of wood. And a number of tables comparing different species, for example radial and tangential shrinkage rates on drying.

    It's free for download. One of these links should take you to it:
    https://www.fs.usda.gov/treesearch/pubs/37440 (click download publication)
    https://www.fpl.fs.fed.us/documnts/fplgtr/fpl_gtr190.pdf (direct link to PDF, not sure if this will work)
     
  5. Dave Bunge

    Dave Bunge

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    To answer your specific questions:
    I've found Oak to be the most prone to cracking of the three woods. So if you've figured out how to dry oak with out cracking, you will have an easier time with the others.

    Ash cuts and sands well. Less tannins than oak, so less likely to rust your lathe bed and no problem with black specs on the wood surface from metal particles (grinder dust) oxidizing. The wood has light colored sapwood and a nice brown heartwood. Usually has a much wider sapwood section than oak. It's good if you can get to the trees while they are still alive. The sapwood turns gray in the standing dead ash trees, I think fairly quickly. This bowl is about 14" diameter and had no heartwood:
    IMG_4723 (2).jpg

    Walnut is beautiful, but comes with some challenges. Many people become sensitized to it. Be sure to wear breathing protection and keep the dust and shavings off of your skin as much as possible. It also has a lot of tannins so will rust any carbon steel it comes in contact with. The heartwood drys well and is not prone to cracking. Sapwood is more prone to cracking. Makes very striking natural edge bowls, especially if you can get a log with narrow sapwood section (one that wasn't growing fast. Yard trees tend to have wide sapwood. Forest trees, more narrow.) Looks best if you can keep the sapwood white, best done by cutting the tree in the winter (less sugars in the wood, and if you're a northerner, you can keep the wood cold) and by processing it into bowl as quickly as possible, within a week or two. Walnut can also have lots of silica in it which tends to dull tools fast, and probably isn't great for your lungs. Be prepared to sharpen your gouges often.
     
  6. Karl Best

    Karl Best

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    Thanks for the specific advice, Dave; that's exactly the sort of stuff I'm looking for. I didn't figure out the oak, unfortunately. I had good success with the stuff I got to fairly quickly, but of the rest, even after using Anchorseal, I've only been able to use less than half. I've now got lots of firewood :).

    Given the number of nearly-dead ash trees I've got I think that I'll fell and prep the largest for turning and the others will just have to go straight to the woodpile. They won't still be alive long enough, and I've only got so much free time.
     
  7. hockenbery

    hockenbery AAW Advisor Staff Member

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    the Bruce Hoadly book mentioned above is excellent.

    You might get a quick overview from the slides I use in mt working with green wood demo
    http://aaw.hockenbery.net/WORKING WITH green wood-HOcompressed.pdf

    warping is directly related to the differences in tangential and radial shrinkage and to the values of the shrinkage.
    If tangential is less than twice radial the wood are fairly easy to dry without cracking Because they don’t warp much.
    Camphor is a good example of a stable wood. Low shrinkage values.
    More than twice require more (or accept less sloppiness)
    The most warping wood on the page is easily identified as madrone high shrinkage values and large ratio of tangential to radial.

    DE79D7B7-A56D-45BF-8199-B35F797724F5.png
     
  8. robo hippy

    robo hippy

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    Well, without seeing the above chart, I would have said that Madrone moves as much as sycamore, but with madrone, it is not a predictable warp. You just never know what madrone will do. I have even had cored sets where some would warp differently than others from the same blank.... I consider black walnut to be fairly stable and easy to dry without cracking. I don't work it any more though as I got sensitive to it.

    I did notice years back that standing dead trees. once you cut them down and start to turn them, have a tendency to crack far more than their 'green' counterparts. Not sure why. So, with your 'almost' dead ash trees, once you start turning them, don't stop.

    robo hippy
     
  9. Karl Best

    Karl Best

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    Thanks, Reed. I'm hoping to get the biggest one down and prepped before it's totally dead. Just instinctively I've felt that a still-somewhat-live tree is going to be better than something that has died. I know that I'm not going to be able to take advantage of all of them before they're totally dead, but I should be able to get at least the biggest.
     
  10. Dean Center

    Dean Center

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    One small addition. The time of year the tree is felled can make a difference in how it behaves. Trees felled in winter, when fully dormant, will be less likely to crack. I guess i would assume the warping would be less, but I don't know for sure.

    One problem I've had with ash is that there are often unexpected knots and these will be a likely source for cracks to form, even in well made rough turned bowl blanks. I'm at the point where I'm not going to bother trying to dry large bowl blanks with knots in them--if they show up during roughing, the blank goes on the firewood pile.
     
  11. Richard Coers

    Richard Coers

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    400-500 different species of oak. There is a wide variety of characteristics. White oak is much harder to dry than red. Not nearly as many ash, but there are different species. I've had some ash that was half the weight as another. Not everything comes in a book. You can't beat personal experience. All my turning wood has been free, or I barter a finished bowl for what I want. So at that price, experimentation is cheap!
     
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  12. robo hippy

    robo hippy

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    Over the years I have been turning madrone, I have found that trees with spring sap in them crack far less than late summer trees or winter trees with little sap in them. No idea why because it seems like it should work the other way. Maybe it is because it is madrone.... Madrone is a very peculiar wood, and I figure that is why we get along...

    robo hippy
     

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