Mastering the BOTB gouge

Discussion in 'Newbie' started by Jamie Straw, Jun 19, 2016.

  1. Jamie Straw

    Jamie Straw

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    I had a good session at the lathe today with my bottom-of-the-bowl gouge (perhaps better called a through-the-transition gouge, but not as alliterative). There are two things I think contributed to an improved experience from the one mentioned earlier in the "Fine cuts..." thread. I think I've had an inclination to swing the gouge, but when I use more of a push-in-the-right-direction mode, it really helps and I've been able to take off thin shavings. Also, having a smaller lathe (Comet 2) that's at the right height really helps everything. I can get one foot just past the tailstock end, and my arms are relaxed, as opposed to having to practically climb on the shelf of the Jet 1236 and shrug my shoulders to hold the gouge in the right place.

    Oh, yeah, a question: taking a poll -- what angle is your BOTB gouge ground at (if you have one)?
     
  2. hockenbery

    hockenbery AAW Advisor Staff Member

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    Bottom feeders have gotten really popular. Anyone using the 45/45 grind on their bowl gouge absolutely needs one because the 45 causes the shaft of the tool to hit the rim about halfway down the sidewall on most bowls. The bevel you want is the smallest angle that lets you ride the bevel to the bottom center of the tallest to wide bowl you do. This will be the sharpest cleanest cut. This could be 60, 70, 80 When you get to 85 degrees you basically have a scraper with a flute.

    I don't use a bottom feeder.
    I grind the heel off the Ellsworth grind and can ride the bevel all the way to the bottom center of bowls that are wider than deep and on bowls just a tiny bit deer than wide.

    Since most bowls are wider than deep. I have never gotten around to dedicating a gouge for bowl bottoms.
    This article by Joe Larese shows some photos of the different grinds on a bowl Some hit the sidewall the Ellsworth does not on this bowl.
    http://c.ymcdn.com/sites/www.woodturner.org/resource/resmgr/GettingStartedinWTArticles/AGuidetoGouges.pdf?hhSearchTerms="Gouges"

    On bowls a lot taller than wide I struggle with the bottom because the bevel not riding wants to make ridges. I get close and use a ring tool and/or a scraper to clean up the bottom. Hunter would work well here.
     
    Last edited: Jun 20, 2016
  3. robo hippy

    robo hippy

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    I have called them BOB tools because I thought Bottom Feeder was a trade mark name, but maybe not. Anyway, I have 60 and 70 degree bevels on mine. The Ellsworth gouge is a 60 degree bevel, at least most of the time, which is why it is usually able to swing through the transition and across the bottom. It can make it through most transitions, but some times I prefer the 70 degree bevel angle, as it comes off the wood at a better handle angle for me, and it will go through tighter transition areas. Of course, rounding off the bottom helps a lot on concave surfaces as it keeps the cutting edge closer to the bevel rub spot.


    "When you get to 85 degrees you basically have a scraper with a flute" Not sure I understand this one Al, probably in part because I do things with scrapers that most don't. I haven't tried a gouge with that steep of a bevel, or a scraper either...

    The trick to getting through the transition and across the bottom is that when going through the transition, you do pivot, and going across the bottom there is no pivot at all, you just push straight across or a little down towards the center and keep the handle angle the same. I talk about that one in my smoothing the inside curves video. This is the most difficult part of bowl turning to master.

    robo hippy
     
  4. hockenbery

    hockenbery AAW Advisor Staff Member

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    Reed,
    My thought is tool with and 85 degree bevel scrapes more than it cuts. A tool at 80 degrees will still cut but not well.
     
  5. hockenbery

    hockenbery AAW Advisor Staff Member

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    I recommend sharpening steep bevels with a platform.
    Using a jig or the handle in the woulverine pocket runs the risk of the pulling the tool down the front of the wheel.
    Saw a serious hand injury occur sharpening a steep bevel with a jig.
     
  6. Bill Boehme

    Bill Boehme Administrator Staff Member

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    I use a BB grind which is a swept back grind that I named after myself. :D It's nearly impossible to distinguish it from an Ellsworth grind except that I use a nose angle between 65 and 70 degrees and grind it on the Tormek with my own unique jig settings. What makes it nice is that I can go from rim to bottom and just rotate the cutting edge to fit the need.

    Any sort of mnemonic is good that that helps you to get your mind focused on what's going on between the cutting edge and the wood rather than where the handle happens to be. The hand and handle positions will take care of themselves just fine.
     
  7. Bill Boehme

    Bill Boehme Administrator Staff Member

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    BTW, the new forum software has a poll feature built in. This seems like a good opportunity to give it a test drive.
     
  8. robo hippy

    robo hippy

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    That depends on how the bevel is applied, and how far you roll it over. The fluteless gouge I use, and a spindle gouge or two that are ground to a ) profile up at a 70 degree angle makes for a very clean cut. Flutes straight up would be dangerous.

    robo hippy

     
  9. Bill Boehme

    Bill Boehme Administrator Staff Member

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    Sometimes just barely scraping by is good enough. :D Sorry, the Devil made me do it.
     
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  10. john lucas

    john lucas

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    I use a Hunter #4 or #5 for a bottom of the bowl gouge. It also works really great as a shear scraper in the transition area if you can't rub the bevel. The outside bevel of the Hunter #4 and #5 is about an 82 degree angle so you can turn the bottom of a bowl with the tool handle almost straight out (8 degree tilt) This allows you to do very steep sided bowls and boxes and still rub the bevel. The nice thing about these tools is the actual cutting edge is about 30 degrees. Very sharp and acute. If you grind a typical bowl gouge to the tip angle is 70 or 80 degrees so you can rub the bevel on the bottom you have a 70 or 80 degree sharpening angle. Not a very clean cut compared to the Hunter 30 degrees. If you use it as a shear scraper in the transition area you are scraping with that 30 degree cutter so it's like using a skew on it's side. Very clean cuts.
     
  11. robo hippy

    robo hippy

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    Bill, from the song Black Rose, 'The devil made me do it the first time. The second time I did it on my own.' It was about a woman, and I think Waylon Jennings made it famous, but he didn't write it..... Love that line.

    robo hippy
     
  12. Douglas Ladendorf

    Douglas Ladendorf

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    John, the Hunter tools sound like an ideal choice in many ways. Perhaps that's the one tool away from greatness! :p What's the learning curve on those and using for bowl bottoms?
     
  13. Jamie Straw

    Jamie Straw

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    Yep! As a beginner, my tendency was to keep swinging -- didn't work so well, LOL, especially on dry Madrona. It was easier to feel what to do on a smallish plum bowl finished yesterday. Just a gentle, patient push toward the center worked great.
     
  14. hockenbery

    hockenbery AAW Advisor Staff Member

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    I try to keep the inside curve going rim to bottom center so there is not a transition but the tool must turn and the handle move to keep the bevel support in place.
    The continuous curve means I am continually cutting through fibers with clean cuts.
    A hemispherical bowl is always attractive, feels good to hold. And is actually the easiest to turn once I mastered making the curve.

    Cutting into endgrain is harder and more challenging.
    On shallow bowls it is inevitable that I cut into the endgrain.
    Cutting a flat bottom requires lots of small cuts and perthaps the scraper.
    Also there is a more pronounced transition to the flat cut.
    On crotch figure or curly grain the fibers are pointing in all directions and even with what I perceive as good cutting I will lift grain that is pointing up from the cuttin edge. Time for the round nose scraper to smooth the surface. On crotch grain I probably use a scraper on 20% of the inside bottoms.

    Design and wood density has an effect surface quality I can achieve with various tools.
    As I approach the bottom of the bowl two things are happening.
    The wood is passing the cutting edge at a slower rate
    The fibers are being cut at a more oblique angle
    To compensate the cut must slow and take less wood off.
     
    Last edited: Jun 22, 2016
  15. john lucas

    john lucas

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    Doug There is a learning curve. If you are good with a bowl gouge with a bevel rubbing cut then the learning curve is very small. If you don't do bevel rubbing cuts then it can keep kicking back on you. IN my video on the hunter tools I show how to pick up the cut when should reduce the learning curve considerably. I always start rubbing the heel of the bevel and then tilt the tool until it starts to cut. That makes it very easy for me to control the tool.

    View: https://www.youtube.com/watch?v=nfp2kvhH6Mo
     
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  16. Douglas Ladendorf

    Douglas Ladendorf

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    Thanks John, that looks very doable. I love the mirror surface seen at the beginning. I know some have struggled, mistakenly treating them like Easy Wood Tools, but they have an entirely different cutting action. Looks perfect for some difficult cuts.
     

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