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Difference Bowl & Rough gouge

Discussion in 'Getting Started' started by Cecil Dean, Oct 29, 2013.

  1. Cecil Dean

    Cecil Dean

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    I know that you are not suppose to use a roughing gouge on a bowl but what is the difference. Is it just the angle of the cutting surface or something else? I still have a hard time knowing which gouge is what.
     
  2. Mike Peace

    Mike Peace

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  3. hockenbery

    hockenbery AAW Advisor Staff Member

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    The gouge types are confusing. A lot of newer turners are unsure as to which is which.

    A bowl gouge is made from a round bar of steel. The flute is ground into the bar.
    A spindle roughing gouge is made from a flat bar that is bent to form the flute and usually has a weak tange holding it in the handle.

    Earlier this year I did a demo for our club on the different types of gouges, how to sharpen them, and how to use them
    I began with a few PowerPoint slides showing the different gouges.

    The first few slides show bowl gouges and spindle roughing gouge.
    http://aaw.hockenbery.net/tgouge intro.pdf

    As you will see there are differences in the bowl gouge flute designs.
    And then there many different grinds on bowl gouges.

    My primary bowl gouge has and Ellsworth grind.
    I also have a couple with a Michaelson grind and a couple with a traditional grind.

    Hope this helps,
    Al
     
    Last edited: Oct 30, 2013
  4. Bill Blasic

    Bill Blasic

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    The Thompson Spindle Roughing Gouge is not made from a flat piece of steel but is machined from a 2 LB block of A11/10V steel and has a 3/4" tang that you won't snap off. Not all SRGs are made equally. But you still would not use this tool on the inside of a bowl, nor would I use it on the outside of a bowl but I have seen a video of it being used on the outside. The A11/10V steel stays sharper a lot longer than M2 which is another benefit.
    Bill
     
  5. john lucas

    john lucas AAW Forum Expert

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    The problem with a spindle roughing gouge is not the tang it's the shape. The tang becomes the problem after you get a bad catch and it bends or breaks the tang.
    New turners tend to use what I'll call course movements of the tools. They tend to make adjustments of the tool in larger motions than an experienced turner. This leads to more catches with any tool but the Spindle roughing gouge has a more unique problem.
    Lets say for the sake of argument the nose of a spindle roughing gouge is like a big U. When your cutting with the bottom of the U the tool rest is supporting the cut right below the U. On spindles this this pretty natural and you rarely roll the cut up onto the side of the U. On bowls it's very very easy to roll the cut up onto the side of the U. In this position the tool rest is not supporting the cut and the gouge wants to roll on it's side and it does this really really quickly and we call it a catch.
    An experienced turner knows this will happen and keeps the cut in the lower part of the U and won't make the more course movements that accidentally bring the cut up onto the wings where a catch can happen
    Now of course you can get a catch with a bowl gouge and it happens all the time but mostly it's because they approach the wood wrong. Because the wings are swept back and the profile is lower the courser movements of a beginner won't create as much danger when accidentally rolling the gouge one way or the other, and if you do the catch won't usually damage the tool like it will on a spindle roughing gouge.
     
  6. john lucas

    john lucas AAW Forum Expert

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    Al Excellent slides. I meant to say that in the last post but forgot. Also Bill mentioned the thick tang of the thompson tool on the spindle roughing gouge. P@N also has that thick tang. It does make the tool tougher and more stable but still doesn't solve the problem of getting catches in the first place. Someday I'll own one of the Thompson roughing gouges. I have quite a few of his other tools and love them.
     
  7. hockenbery

    hockenbery AAW Advisor Staff Member

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    Bill and John make excellent points.

    Catches occur when the wood can drive down onto to the tool. In the catch the cutting edge is going as deeply into the wood as it can.
    With a 1/2 bowl gouge this depth is limited by the depth and width of the flute at which time the tool just can't go any deeper and the gouge breaks free.
    This usual results are a deep scar on the wood and sometimes a bowl is pulled from the chuck or the bowl being broken.
    These catches can cause injury from the flying wood.

    With a wide spindle roughing gouge a catch can go much deeper and wider into the wood since the flutes are typically an inch or more wide.
    The resulting catches can be catastrophic, breaking, tools, tool rests, banjos, and of course inflicting much more damage to the wood.
    My guess is you won't break a Thomson spindle roughing gouge so a big catch is going to break something on the lathe or pull the bowl airborne.

    For the reasons above the bowl gouges larger than 5/8 diameter bar should also be avoided by those with "course movements"
    Bigger gouges > bigger catches

    Al
     
    Last edited: Oct 30, 2013
  8. Cecil Dean

    Cecil Dean

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    Thanks for the info. & links.
    Cecil
     
  9. David Wilkins

    David Wilkins

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    Catches

    I was fortunate to be able to spend a few days with Mike Darlow. He accurately describes a catch as "a thickening of the shaving" and it is rapid. Roughing gouges milled from round stock like p&n or thompsons are the best in the world and worth purchasing for heavy spindle roughing. Bowl gouges are incredibly versatile tools that 99% of the production bowl turners use.
     
  10. john lucas

    john lucas AAW Forum Expert

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    I use a bowl gouge for the vast majority of my work. Hollowing boxes and turning them. Same for Goblets. It's just an all around comfortable tool to ue once you learn to use it. I do switch to spindle gouges and skews when necessary.
     

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