What angles do you grind your turning tools?

Discussion in 'Woodturning Discussion Forum' started by Tim Leiter, Oct 21, 2017.

  1. robo hippy

    robo hippy

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    I thin, the NRS works better on spindles if you use it for a peeling cut rather than a scrape. The peeling cut is a bevel rubbing cut, and I should do a video on that some day. This is a tangent I went off on due to watching Eric Loffstrom demo a lidded box form. He used the peeling cut with the skew rather than the skewed bevel rubbing cut. The resulting peeling cut surface was not as clean as the bevel rubbing cut surface, but it was a '220' grit surface, and there were no tool marks which are standard for most of we mere mortal skew users. This, I think is the same type of cut that is shown in the Sorby clip which I now have to go find and watch again...., and clip and paste here...

    robo hippy
     
  2. Bill Boehme

    Bill Boehme Administrator Staff Member

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    If you're doing a peeling cut then why not use a skew? Nothing else beats it.
     
  3. robo hippy

    robo hippy

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    Here it is. The top bevel, I am guessing is in the 20+ degree range.... They start handle down and bevel rubbing, then raise the handle till it starts cutting, which is pretty much a peeling cut. Same on the spindles. I have used my Big Ugly tool, and other scrapers, one a 70/30 grind for the same cut. Still prefer the burnished burr. As I said above, this type of NRS on spindles gets rid of tool marks where we wiggle through the curve rather than one smooth clean sweep... Maybe some day my skill levels will approach those of Allan Batty and Richard Raffen....


    View: https://www.youtube.com/watch?v=lvqwrZY2QJg


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  4. robo hippy

    robo hippy

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    Okay, went out to the shop to try a couple of variations with a 70/30 NRS on a big leaf maple spindle. The cuts were bevel rubbing peeling cut, and non bevel rubbing cut. I used grinder burr, burnished burr, and burr totally honed off. Best cut/cleanest surface was a peeling cut with the totally honed off burr, close second was burnished burr. The non bevel rubbing cuts didn't do as well, but more of an 'okay' surface. So, that Sorby type of NRS should do better with a peeling type cut.

    Dang, now I need to try it on a bowl.....

    robo hippy
     
  5. robo hippy

    robo hippy

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    Hmm, different wood for the bowl, a particularly nasty piece of myrtle/California Bay Laurel, which does have an inter locking grain that some times wants to tear rather than cut... Best surfaces came from burnished burr shear scrape with M42 shear scraper. Didn't try gouges cause I don't use them for that. The 70/30 in peeling cut seemed to rough up the bevel rubbing gouge cut. The 30/30 NRS left a good surface if I went over it enough times, which you have to do for this type of wood, or you start with 120 or 100 grit for your sanding. Pretty much the same inside and outside of the bowl... Results didn't vary much on honed and no burr to honed and burnished burr... Since this was a more difficult wood, results would be fair to good on other more normal woods.

    robo hippy
     
  6. robo hippy

    robo hippy

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    Bill, most of the time, the peeling cut is used for sizing. I am using it for a finish cut. Biggest difference for me is that some thing like the 70/30 grind, that is honed, I get a really clean cut, and no tool marks. I always get tool marks with the skew, and they are difficult to sand out. I did notice that a 25/25 skew seemed to get a cleaner cut than the 30/30, but I find the 70/30 to be more comfortable because I can hold the handle more level without having to reach way out. I have a couple of 1/4 round profiles for the skew grinds, and at least one ) nose shape which is excellent for coves. Generally it leaves a 220 grit surface.

    robo hippy
     

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