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Finishing a deep vessel

Discussion in 'Getting Started' started by Scott Barton, Oct 8, 2012.

  1. Scott Barton

    Scott Barton

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    I just tried turning a vase in, what I believe, to be birch. I turned it with the grain parallel with the bed. I had an enormous amount of tearout. Even with very freshly sharpened tools. The wood was semi-green, so I didn't really expect the problems I had.

    I used an forstner bit to hog out the middle and an Easy Woods scraper to do the rest. Again, I was really surprised my the amount of tear out I had.

    On the outside, I could use a skew and a round nose scraper to get a decent cut. On the inside, I never found the right tool to get a smooth cut.

    The is vase is about 12" or so deep, with a 2.5" opening. For the life of me, I can't figure out a way to clean up the inside. I tried attaching some sandpaper to a stick, but I could never get any real pressure on it to remove any material. Obviously, I can't get my hand down in there.

    What do you folks use when the material is fighting you and you can't use your hands? Any help would be greatly appreciated.
     
  2. Bill Boehme

    Bill Boehme Administrator Staff Member

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    I don't know about birch, but perhaps you need to let it dry before finishing the interior. Also, hardly anybody tries to get a great finish on the interior beyond how far your fingers can reach.

    Make sure that the cutting edge of the tool is exactly on the centerline or if you err, it should be high rather than low. Also, make certain that the tool is not being tilted up or down.

    I would guess that if the wood is too green, it may be warping as you turn it or you are being a bit too aggressive, or straying off centerline. Leave enough thickness that you will be able to make clean up cuts after it has dried and warped.
     
  3. bernie

    bernie

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    narrow the opening

    You might want to glue a ring of wood (probably contrasting wood) to the top so as to close the hollowing opening and keep nosy fingers out.
     
  4. Steve Worcester

    Steve Worcester Admin Emeritus

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    it is mostly tool, experience and technique.
    End grain is a pain, and the Easywood isn't making it easier here.
    But I don't understand freshly sharpened tool and Easywood. Of did you try one tool and go to the Easywood?

    For the insides like this, you need something that cuts or possibly the Easywood in a sheer cut.
    There are times where I may try several tools before I get the finish I want. Then again, there are times where I never get the finish I want, so I keep trying, blow it up, and make another one.
     
  5. Scott Barton

    Scott Barton

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    I think my eyes were bigger than my tool collection. I hogged out the inside with a forstner bit and then when I set to work some more on the inside, I realized that none of my tools could get in there deep enough.

    I started with my fingernail gouge to try to shear cut at the shallow angle, but I just couldn't get a proper angle. So, then I resorted to my EWT, and all that did that was tear up the inside. It wasn't slicing the fibers, just yanking them out. I change the tip, not much better. It was like the strands weren't strong enough to hold themselves while I cut them, so they just came out.

    All things being equal, I will bet it was partial bad technique and something to do with the grain orientation and the green-ness of the wood. I had bad tearout on the outside and I know how to make clean cuts or how to find the right tool/technique to get a decent cut, so that should have been a red flag. I should have seen the trouble coming on the inside.

    I didn't want to wait to let it dry too much because I could see it starting to crack. I wanted to clear out as much material as possible to ease the drying process. I also just read about someone preaching to finish the inside and outside of a green piece so as it dries and warps, you are done with it. It then shows off the warp. So, I was experimenting a touch as well.

    I would normally like the idea of adding another piece, but the form is pretty nice, and I don't want to add to it.

    If I could have better reach, I could sand it smoother. I didn't know if there was some sanding trick like a bowl buffer that was made of sandpaper for times just like these. Seems like I would not have been the first person to ask this question.
     
  6. MichaelMouse

    MichaelMouse

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    The cutters like the ones on Hunter tools, or their hollow cousins the ring or hook tools are what I've found best. It's really a gouge mounted at 90 degrees to the shank, and using that concept as a starting point helps in getting the right cutting angle. Your fingernail gouge at about 10:00 o'clock is a section of a circle at perhaps 35 degrees to the shaft. I don't use them for the gross work, merely the final form and finish.

    Gross work is great with a pointy gouge. If you can spare a gouge, grind it back so the edge is almost vertical. http://i35.photobucket.com/albums/d160/GoodOnesGone/a63b77ab.jpg

    In use it's like a straight or skew chisel. Tilt on the handle gives you more or less skew, and it ejects shavings even when working narrow openings, though this shows a goblet progress. http://i35.photobucket.com/albums/d160/GoodOnesGone/5fa71f2e.jpg You can see by the form of the shavings there's not much downhill. If you're working where there is, you'll get twisted shavings which will have to be broken and extracted.
     
  7. john lucas

    john lucas AAW Forum Expert

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    Scraping cuts were definitely the problem along with the green wood. Green wood doesn't scrape well. You could rough turn it and let it dry and it will cut a little cleaner.
    Cutters like the Hunter #1 mounted in a swiveling tip will let you cut with a bevel rubbing cut from the bottom out or you could rotate the cutter and cut down but that would be against the grain.
    Hook tools and ring tools as well as the Berger tool will cut well in this situation as well.
    The advantage of all of these tools is that you can mount them in a 3/4" thick bar and cut a lot deeper with less vibration. Using a captured bar system like the Jamieson with the #1 Hunter tool makes it a breeze and you'll get a finish that is easily sanded.
     
  8. hockenbery

    hockenbery AAW Advisor Staff Member

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    Hollowing endgrain is challenging.

    Generally cuts from center to outside work well with the tip of a gouge cutting perpendicular to the lathe axis.
    Often you are over the tool rest a good bit so light cuts.
    Be sure to set the tool rest so you are cutting a bit above center. Below center invites a catch.

    Best cuts are from the bottom Center up the wall to the rim. Ring tools and hook tools allow this cut to be made.
    some round carbide tools do ok here too.
    A captured hollowing system is one of the easiest ways to hollow endgrain forms.
    The back hollowing with a spindle gouge that Raffan uses in some of his videos works well but can be difficult to learn.


    Depending on shape it is often better to hollow first then turn the outside.
    The stress of hollowing can crack thin walls.
    Goblets and vases are generally hollowed first then the outside turned to an even wall.
     
    Last edited: Oct 9, 2012
  9. Scott Barton

    Scott Barton

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    More great comments.

    If scraping was the problem, I definitely chose the wrong approach.

    I have never seen a gouge like that. I think I need to give that a shot. Did that start as a bowl gouge or a spindle gouge?
     
  10. Bill Boehme

    Bill Boehme Administrator Staff Member

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    With a 2½" opening and 12" deep that is too much overhang for hand holding a hollowing tool. I don't know of any hand hollowing tools with that much reach except for those with an arm brace or side handle. For hollowing tools the handle should be about three times longer than the maximum overhang or more for somebody who has turned a few hollowforms. Even an experienced hollowform turner would find the going tough under those conditions.

    I do not see a problem with the wood being green. It cuts a lot easier than dry wood. However, it will move and cuts need to be light. Most people make light pull cuts starting at the top and working their way towards the bottom. You might also need a steady rest because the tear out problem might be a result of the walls vibrating. I prefer a faceplate to a chuck for large hollowforms.
     
  11. MichaelMouse

    MichaelMouse

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    I think that one is a "detail" gouge. Bought one when they first got a name and couldn't find a legitimate use for it, so I reground. The way they grind away about a third of the depth to make a "spindle" gouge now, I would say it's not the gouge of choice. Bowl or detail. Meat under the bottom of the flute doesn't get in the way with the method of use. I also have some of the first cylindrical pattern "spindle" gouges, the kind with nothing ground away. The 1/4" is ground similarly for use in ornaments.

    You don't have to punch a hole first, because the point doesn't skate when you use it. Tilt right to go center, left to go out and continue to your desired depth/breadth. Leaves a cone at the bottom to clean up with a fingernail or ring tool.
     
  12. Col Smith

    Col Smith

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    G'day Scott,

    In the past I have used "flap wheels" for the sides & sanding pads on the bases.
    http://www.ebay.com.au/itm/170918672144?hlp=false
    http://www.cws.au.com/shop/category/-sanding-pads
    You will need an electric drill for this, & a 3 or 4 wheel steady to take the side pressure.
    Both of these fitted into an extension bar of what ever length you require.
    I used these on the 15" Jacaranda vase with great results.
    Extension bars can be bought in most lengths these days.

    HTH

    Col
     
    Last edited: Dec 24, 2012

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