Is green wood more prone to tearout?

Discussion in 'Newbie' started by Hy Tran, May 29, 2016.

  1. Hy Tran

    Hy Tran

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    I've acquired some very green silver maple, and have major issues with tearout. I did a somewhat green douglas fir blank (chips were cool, not hot), and had some tearout. In both cases, I'm trying to turn to finish, not twice-turn.

    The tearout appears to be when I'm hitting end-grain

    Has my technique gone south, or does green wood tend to tear out a bit more than dry?

    Thanks!

    Hy
     
  2. hockenbery

    hockenbery AAW Advisor Staff Member

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    I finish turn wet wood for most of my hollow forms and natural edge bowls. Quite a bit of silver maple.

    Silver maple is a soft maple. It is more prone to tear out than say cherry.
    Cutting with a sharp gouge bevel riding cutting foot to rim on the outside you should get no noticeable tearout.
    Or at worst tiny tear out on the backside of the end grain you can clean up with shear scrap.
    A light pull cut almost never leaves tear out.

    Usually tear out is worse on the backside of the endgrain.
    Maybe the photo shows what I want it to. The cut on the outside is foot to rim.
    The cut should be toward the rim. Big arrow. The flute faces the big arrow direction.
    However as good as we think are some small component of the cut is upward or toward center. Little arrow.
    The cut toward the center is okay on the side grain and as you cut the end grain it is okay because there are supporting fibers behind the first half of the end grain.
    Then it switches to not ok as you cut past the center of the grain into the backside of the end grain.
    Here the fibers are only supported in the rim direction, in the vertical direction there is only air behind the fibers and they will bend and tear. Also If the cut us up the grain can run into the tool edge and tear if tool edge to too much up it catches.

    Flat Scraping with the gouge will work on the face grain and the first half of the end grain then tear out on the back side of the end grain.
    You might be able to scrape a harder wood with no noticeable tear out.

    I have to be careful roughing wood like soft maple.
    My roughing cut does not ride the bevel and I take a 3/4" bite. That 3/4" shaving is attached to the bowl and as it is lifted it pulls fibers with it.
    So with the soft woods I have to switch to lighter cute earlier. My early roughing could have 1/4" deep tear out so I need to switch to smoothing cuts when I still have 1/2" of material to remove.

    Maybe we could chat in Atlanta.
    Al
     

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    Last edited: May 30, 2016
  3. John K Jordan

    John K Jordan

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    I am talented enough to get tearout on both green and dry wood! I can't answer whether one is worse - depends on the wood.

    First thing I do is resharpen on the Tormek and then hone the gouge edge to a razor sharpness.

    If tearout is still a problem I douse the wood with shellac cut with 50 percent alcohol (dries quickly) or apply sander sealer. Make a finish cut; repeat as necessary. This tends to stiffen up the fibers and reduce tearout.

    On extreme cases with horrible wood (maybe spalted, punky, etc?) I douse with very thin CA glue instead of shellac. I put it over the whole piece for a consistent look. Cut, then repeat if necessary. Works better with smaller turnings. The downsides: This takes a lot of CA glue and makes horrible fumes! The upside: the wood won't tear out. (I haven't tried this with wet wood, only dry.)

    JKJ
     
  4. Hy Tran

    Hy Tran

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    I'm going to try to take a close-up photo and post it. Yes, you're absolutely right (both Al & John)--In the section where I have tearout, the grain is pointing towards the gouge.

    I did sharpen the gouge--perhaps not razor sharp (I'm not brave enough to shave with my gouges), but "sufficiently sharp." I was convinced to no longer hone the gouges, but to still hone the skew. Still a novice. Would you recommend honing the bowl and spindle gouges? The majority of folks I've talked to say to just have your grinder nearby, and "just before you feel the gouge is dull, touch it up on the grinder." Or just honing if I'm having trouble?

    50% shellac sounds like a good bottle of spirits to have :cool: No issues applying that to wet wood? I don't want to douse with CA glue--these are practice utility bowls (salad, popcorn, etc.), not give-away or sell. Just working on my technique and trying to get good muscle memory. I do try to use a bevel-riding cut on all cuts, whether practice or "good give-way" stuff--a matter of building muscle memory.

    A side note: Working with the green wood, I was taking deeper cuts than I would on dry wood. The shavings went farther than they usually do, and covered my grinder, which is set up just behind me. Next piece of shop equipment: A drop cloth to cover the grinder, along with the 50% shellac/50% alcohol mixture in a bottle.

    Yes, I'll be around in Atlanta--if I catch either of you, I'll try and chat.

    Best,

    Hy
     
    Last edited: May 30, 2016
  5. hockenbery

    hockenbery AAW Advisor Staff Member

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    Some people hone bowl gouges. I don't.

    I don't hone my bowl gouges except to clean and polish the inside of the flute with a slip stone when it gets sap and stuff building up.
    I use it fresh off the wheel, currently an 80 grit CBN that replaced a 60 grit Norton. Most of my gouges have the Ellsworth grind.


    Spindle gouges I usually use off the 180 grit CBN that replaced a 120 grit Norton. I might hone it before turning a cove detail on a finial
    For turning beads on bowls I don't hone it. The finials I sand with 320 and 400. The coves with 220 if I don't hone.


    Al
     
    Last edited: May 30, 2016
  6. Hy Tran

    Hy Tran

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    I grind gouges on a 180 CBN that I got at the Pittsburgh symposium. Before that, I ground on a 120 white AlOx. Skew, spindle roughing gouge, and negative rake scraper still go on the 120 AlOx.

    The bowl and spindle gouges are done on the Oneway Wolverine jig, with a jig for setting the nose stickout, and another jig for setting the pocket-to-wheel distance. My grinds are very repeatable (verified with magic marker on the bevel). I don't know what angles they are, but I'm used to it.

    My skew gets touched up with a red diamond credit card or handheld hone.

    If I remember (won't be until after Atlanta, I don't think), when I cut up some more of that green silver maple (I still have a 10x20x4 chunk, well sealed), I'll reserve a small spindle orientation piece to try with the skew.
     
  7. john lucas

    john lucas

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    Hy typically when I get tearout I do several things. First is to simply try cutting in the opposite direction. It usually changes the tearout 90 degrees from where it was before. sometimes the tearout in the new sections is less, sometimes not. The other things I do is switch to gouges that have a more acute grind. ( you already said you freshly sharpened which is my first form of attack. My normal bowl gouge has a nose angle grind of about 55 degrees. If I can I'll switch to my 40 degree bowl gouge. If that doesn't work I'll try my 35 degree spindle gouge. I should say at this point I have also made a concerted effort to try not force the gouge to cut. I relax, turn up the speed of the lathe a little if I can do that safely, and then try to feel the gouge cutting rather than pushing it through the cut. If all that doesn't work I switch to a Hunter Osprey or Hunter Hercules. These have a cutting edge that is about 30 degrees so that almost always works along with taking a lighter cut and not forcing the cut. If all of that doesn't work it's time to soak it with thinned Lacquer to harden the fibers. thinned shellac works also. It depends on what your final finish is as to which one I choose. Thin CA also works but is a little expensive to use on larger areas.
     
  8. robo hippy

    robo hippy

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    Silver maple is one tree for me that is difficult to cut clean, though not as bad as cotton wood. Out here, a tree that is 30 inches at the stump is 30 years old, so it grows way too fast. Kind of like John said, of one tool doesn't work then I try another, V flute, U flute, half round flute, parabolic flute, detail gouge flute, fluteless gouge. Since I got my 600 and 1000 grit wheels, that fine of a grind does make a difference for finish cuts, but goes dull too quickly for being good for heavy roughing, that is what scrapers are for... Some times a bevel rubbing cut works, some times you have to shear scrape with a 1000 grit burr, some times the negative rake scraper works best. I have been turning a myrtle log and some pieces have been a royal pain, but I found out if I let the blank sit for a day or three before turning, it cuts way better. Just 'because'. Madrone cuts beautifully no matter what tools you use.

    robo hippy
     
  9. Bill Boehme

    Bill Boehme Administrator Staff Member

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    I'm sort of like JKJ ... I sharpen on a Tormek and while I don't always hone, I do it if necessary. If cutting wet wood, gummy sap and fibers will often build up near the cutting edge and that can interfere with getting a clean cut ... box elder seems to be bad about that. Sometimes wet wood will be punky if the tree has been down for a few years. We sometimes mistakenly refer to wet dead wood as "green" wood. They have a lot of characteristics in common, but punkiness is much more common in wet dead wood.

    I buy Starbond Super Thin CA by the pint and sometimes use it on moderately wet wood to stiffen the fibers on soft end grain.
     
  10. John K Jordan

    John K Jordan

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    Do you have a good source for Starbond? I've bought quantities of low quality CA and was sorry.

    JKJ
     
  11. Fred Belknap

    Fred Belknap

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  12. John K Jordan

    John K Jordan

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  13. Bill Boehme

    Bill Boehme Administrator Staff Member

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    I stock up every year when I go to the SWAT symposium. The CPH International people are always there with a large supply of all their products. They also usually have some show specials when you buy quantity. I'm sure that they also go to the AAW National symposium.
     
    Last edited: Jun 5, 2016
  14. John K Jordan

    John K Jordan

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    Thanks, maybe I'll go to one of those some day. I'll buy a little from Amazon to try. I've gotten used to having CA around, imagine that.

    JKJ
     

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