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Thread: Towards improved skew control.

  1. #1
    Join Date
    Jul 2011
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    The Gorge Area, Oregon
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    Towards improved skew control.

    I believe based on some experiments that sharpening your skew on a stone instead of (or in addition to) grinding it will yield improved tool control. I don't have a sufficiently large sample size to support this yet but the bit of anecdotal evidence I've gathered seems moderately compelling. I would be interested if anyone else either already knew this, or can give it a try if you've found the skew tricky to see if it helps at all.

    To start with I basically never grind my skew, but instead use those little trend diamond paddles for day-day sharpening so hadn't really put this together in my head before.

    I was messing around with it last week and decided to regrind the edge a little bit differently (same sharpening angle but just changing the "skewed" direction a smidge)... Well boy howdy it was suddenly spiral catch city! Especially when trying to turn beads, planing was ok but rolling any curves was not happy.

    Took it back over to the diamond paddles and sharpened it a bit more with them which reduced the hollow grind a little and it settled right back down nicely. This was with the same basic included angle on the sharp bits and not changing the shape of the rest of it (or the height of the tool rest .. which can also make a very large difference).

    My hypothesis is that a hollow ground bevel doesn't provide enough support behind the cutting edge and sharpening it on a flat stone/diamond gives just a wee bit of extra support behind the edge which helps keep the edge from rotating to quickly into the stock. You can also get the skew sharper by honing than you can with ~most~ grinders which I believe also helps, I do notice that if I've been skewing around a while the probability of a backwards spiral catch goes up and then back down once I sharpen things up again.

    So if you're still fighting backward spiral catches with the skew try honing the edge on a bench stone or diamond paddle or.. whatever you use for flat blade sharpening. It doesn't take a lot, less than half a millimeter of flat behind the edge seemed to make a pretty measurable difference.

    I also repeated the experiment once just to see and it seemed to have the same behavior (grind - whee many catches, then sharpen on the diamond paddles and great joy).

    The effect is very likely larger or smaller depending on how steep of an angle you grind your skew at. I like mine pretty poky so I suspect that may increase the effect somewhat.
    Love thy neighbor, yet pull down not thy hedge.

  2. #2
    Join Date
    Mar 2015
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    Parker County, Texas
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    1,295
    I ran into problems with my skews when I would try to sharpen them on the "slow" grinder which spins at 1850. Even on a finer grit wheel. I ended up just using that to reshape my goofs with it and using those diamond paddle hones like you are using, Ryan. After I bought that 110 rpm wet sharpener with the 220 grit wheel I tried it. Now some turners think I am nuts because I rarely use a sharpening jig. I mainly do it freehand. Not bragging but I have fairly large muscled up arms and shoulders from constant weight lifting and holding a skew or gouge steady is no problem. Sharpening my skews on the wet grinder works well. And, the edges hold well. I still do the touching up with the paddle hones, though. They are quite the useful tools. I use them on the gouges as well. If someone does a lot of turning I really recommend one of those real slow wet sharpeners. And, the hones.

  3. #3
    Join Date
    Feb 2007
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    North West Indiana
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    6,060
    More than the grind, the tool rest setting is most important to my students. The tool rest predominantly is set so the tool is at midpoint of the turning. I have my students set the tool rest high (3/4 or more high) and this greatly reduces the number of catches. On a side note, to low of a tool rest is probably the biggest culprit in any of their poor turning, blow up situations.
    Jon

    God and family, the rest is icing on the cake. I'm so far behind, I think I'm in first place!

    Host of the 2015 FAMILY WOODWORKING GATHERING

  4. #4
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    Oct 2006
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    ABQ NM
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    I believe it's Eli Evisera who pushes the idea of creating a convex grind as opposed to a concave grind on a skew. As I recall, his theory (much like your hypothesis) is that you get more of the bevel supporting the cutting edge that way. He also hones on a felt wheel charged with honing compound after getting the initial shape on the grinder. (Or was it a wood wheel? It's been several years since I saw his demo. Stu would likely know.)
    When the going gets weird, the weird turn pro. - Hunter S. Thompson
    When the weird get going, they start their own forum. - Vaughn McMillan

    workingwoods.com

  5. #5
    Join Date
    Jul 2011
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    The Gorge Area, Oregon
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    Jonathan, I agree 1000% on the rest height, that certainly makes it all possible.

    The behavior i was observing was without changing the rest height between tests so there was an additional effect.

    Good call Vaughn, I found Stu's videos on Eli's method, will have to take a closer look at those:

    https://www.youtube.com/playlist?lis...7F96FDC5C98D6F
    Love thy neighbor, yet pull down not thy hedge.

  6. #6
    Join Date
    Feb 2013
    Location
    Clyce, Texas
    Posts
    176
    Sat in on a demo with Alan Lacer a couple of weeks ago. He uses skews for just about everything. He grinds then hones. Gets them scary sharp. And he cuts high on his blank, too. I've been honing only, but learned from him that I need to do some reshaping on the grinder then hone better and raise my tool rest.

  7. #7
    Join Date
    May 2007
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    Kansas City, Missouri
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    13,112
    Interesting info. I've got a job to do on mine and will give it a shot.
    Darren

    To a small child, the perfect granddad is unafraid of big dogs and fierce storms but absolutely terrified of the word “boo.” – Robert Brault

  8. #8
    Join Date
    Feb 2008
    Location
    Grand Rapids, MI
    Posts
    383
    A lot of my experience has been stated here already. I too have found hollow grinds more "iffy", so I made a custom sharpening machine that allows me to quickly sharpen a skew without a hollow grind. Of course, honing is alays good.

    I agree with the tools rest comments. If its too low then certain types of cuts become very problematic.

    Another thing that is absolutely critical to this conversation is the rigidity of the tool rest. I know, Ryan, you did your experimentation with a consistent setup so this isn't directed to your experience directly, but most tool rests suck. I often recommend to turners to practice technique over the post before going to the end of a 12" rest. If you do well over the post but not at the end of the rest chances are you have too much flexibility/bouncing/vibration in the rest.

    - Hutch
    Last edited by Matt Hutchinson; 05-09-2017 at 11:37 PM.

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