Making big rim adjustment on 2nd turning of bowl

Discussion in 'Newbie' started by Jamie Straw, Jun 24, 2016.

  1. Jamie Straw

    Jamie Straw

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    I've had a couple of bowls recently that were finished drying, and since the rims were nearest the pith (but didn't include the pith, of course:)) there were the usual peaks in the rims. One of them, I needed to take off a half-inch+, and the wall thickness was a half-inch, so I wasn't sure the best way to take that off. Actually ended up scoring a line with a parting tool, and then using a little saw-knife and then thin-kerf saw (lathe off) to cut through it. Is there a better, more kind-to-the-hands way to do this?
     
  2. robo hippy

    robo hippy

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    I think it is easiest to use the parting tool, and stand out of the line of fire.

    robo hippy
     
  3. MichaelMouse

    MichaelMouse

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    Block plane works fine. Prefer low-angle for the reasons shown in my "edge" posts.

    DON'T push a tool into the rim of a rotating piece. Centrifugal force and cutting uphill wants to toss it back at you. Start in the middle of the wood, touch with the tool, and cut downhill and out or in. Be careful as you cut in. Swing the tool going inward, so it's making its own stop cut as you enter.
     
    Last edited: Jun 25, 2016
  4. Fred Belknap

    Fred Belknap

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    Jamie you can just face up the rim with a gauge or a scraper. I usually face up the rim before I do the outside and use a bowl gouge to do it. I often put some chalk on the edge to make sure I get it face up all the way around. I hope I am addressing your question correctly but if you are talking about the diameter then if you are 1/2 inch out of round and the wall thickness is 1/2 inch your rough out is a bit thin but still may work as it turnes you only need to remove 1/4 inch off each side. By the time you get the outside round there may not be enough wood to round the inside. It may still work as the inside 1/4 inch will not come off the same part of the bowl as the outside.
     
  5. hockenbery

    hockenbery AAW Advisor Staff Member

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    I turn the rim first. Similar to Fred.
    It is quick and easy. It also gets me the biggest bowl and keeps any grain alignment I did with the rough out.

    1. I jamb Chuck the dried bowl over the jaws of the Chuck tailstock center in the middle of the dried tenon ( use the roughing center point if it is there)

    2. I Align the high points and low points of the rim. Loosen the tailstock and shift where the bowl rests on the Chuck. I put my thumb or a pencil on the tool rest to check that the high points pass the same spot on the tool rest and are the same distance from the tool rest.
    Repeat for the lower
    Each adjustment is made by getting the parts you want to adjust in verticle alignment and shifting the top one toward or away from the tailstock.

    3. Turning is done from the headstock side with the bevel edge of the gouge parallel to the ways of the lathe. I make a 1/4" cut into the outermost edge of the rim a 1/2" or so toward the tailstock.
    Move the gouge and cut again. Each cut after the first must stop just shy of the previous cut.
    Here the side ground gouge works really we since I can then scrape all the bumps to smooth top of the rim.

    Cutting into the rim from the top of the rim cut the long fibers.

    This method
    Gets the bowl in weight balance faster since the rim warp is the most out of balance part of the bowl.
    It will give you the largest bowl as it align
     
    Last edited: Jun 25, 2016
  6. hockenbery

    hockenbery AAW Advisor Staff Member

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    Reed,

    Using a parting tool can be extremely dangerousness for the novice.
    Cutting into endgrain can easily result in a massive catch.
    It can be done but the parting tool must be pointing down and used as a scraper.
    The efficient peeling cut used in spindle work will give a massive catch on endgrain.

    Cutting into the face grain is inefficient and difficult with a parting tool

    I teach students to cut the rim with a gouge straight in at the top of the rim.
     
  7. Jamie Straw

    Jamie Straw

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    Yesterday I sharpened one parting tool on the new CBN wheel, ad it cuts so much better. I'll try that on the next rim -- didn't seem practical the first time I tried it.
     
  8. hockenbery

    hockenbery AAW Advisor Staff Member

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    Be sure to use it as a scraper. If the bevel contacts the wood you risk a big catch.
     
  9. Jamie Straw

    Jamie Straw

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    Oh, yeah, right.
     
  10. Jamie Straw

    Jamie Straw

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    Nope, not diameter -- "height" if you will -- cutting the rim back to get rid of the "peaks" that occur when the bowl dries and the rim (rather than the tenon) is toward the center of the tree.
     
  11. Jamie Straw

    Jamie Straw

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    Thanks, Al. You had kindly provided this instruction in another thread, and I have to confess -- though I read it over a number of times, I just didn't "get it.":( Rather than expose my confusication to the whole world, I planned to PM you but that was right at the forum changeover. Perhaps we could have a Conversation. I'll write you tonight.
     
  12. hockenbery

    hockenbery AAW Advisor Staff Member

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    This process is hard to put into words.
    I need to get a video of the process. I can do a few pictures and show the set up.

    I just did this in a demo a couple months ago unfortunately the club did not make a DVD for me.

    Al
     
  13. Jamie Straw

    Jamie Straw

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    Yep, a video would be great, but I'm sure a couple of pictures would straighten my brain out.:p Also, then I might know what part of the written description threw me off. Those guys owe you a DVD!:D
     
  14. MichaelMouse

    MichaelMouse

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    Like this, I assumed. http://i35.photobucket.com/albums/d160/GoodOnesGone/1-Oak-Distorted.jpg I tried putting up a couple of videos showing swing entries out and down on the rim and then showing the instant back stop, but I guess Photobucket is still looking to see if they're dirty or political. If they ever come up ....
     
  15. Bill Boehme

    Bill Boehme Administrator Staff Member

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    Not sure why, but McAfee didn't like Photobucket.
     
  16. Jamie Straw

    Jamie Straw

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    Not surprised. I don't go t PB any longer --- rarely get anything out of the visits.
     
  17. Bill Boehme

    Bill Boehme Administrator Staff Member

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    Maybe it's the junk ads.
     

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