NRS angles and burr

[robo hippy]

I was chatting with John Jordan about stropping the skew, couldn't remember where, and he commented about sharpening his NRSs removing the burr and then burnishing the burr back up. I was introduced to the NRS at a 3 day work shop with Stuart and Allan Batty, and Allan was telling stories about turning billiard balls out of elephant ivory, a couple of years process. He was using a skew chisel. I experimented around with them a bit, and didn't really care for them that much since they were so high maintenance. Some where along the line, I started to figure that with the skew chisel variation, there just was not enough metal under the burr to support it like my Big Ugly tool which is sharpened at 70 degrees on my robo rest. So, I started to experiment. I ended up with 30/60 for the angles on my robo rest. The actual measures are 25/55 since all of my angles are 5 degrees off for some reason. Our club had Carl Jacobson demo at our club and he used D Way NRSs. Jimmy Allen, owner of D Way was using angles some what similar to mine. I did take one, and grind it to 45/45, or 40/40, can't remember, and the burr was gone in seconds, kind of like the standard skew chisel type NRSs, so I converted it back to my standard design. So, I am wondering what angles others use. For sure, the convenience of my grinder rest to exactly repeat angles makes this sharpening set up more simple than other systems. I generally just use the burr off of the grinder and it is good for several bowls rather than starting with the heel on the inside of the bowl, and going to the toe of the NRS by the time I get to the rim, and then that burr is done/gone. I can use mine for a couple of passes, then burnish the grinder burr down, then back up and I am good to go for another bowl or two, and I can do this a couple of times before needing to go back to the grinder. So, what angles do you all use out there?

robo hippy

 

[Dean Center]

I use a 4 on my Roborest for both sides, as I'm trying to apply KISS. But I don't think I'm getting the most out of the NRS, so don't be like me. Maybe I'm raising the burr with the burnisher incorrectly or something, but I don't generally don't get a better burr by burnishing. Maybe it lasts a little longer. Certainly, the burr wouldn't last more than one bowl. (though that's dependent on the wood being turned and the surface achieved before the NRS gets applied, i.e. how long/much work the NRS is asked to do)

 

[Alan Weinberg]

I don’t think most burrs last more than 30 seconds of turning. Probably easy to assess.

 

[John K Jordan]

I use a variety of angles on NRS, depending on the function. Some work better on end grain and tiny things, some better on broader curved surfaces.

My favorite NRS for bowls, platter, and such are these, sharpened with the same angle on each side like a skew, but with, I think, a 60-deg included angle. I sharpen both the profile and the angles like this for specific reasons.



This shows one on edge showing the included angle. (I made this from a Thompson skew, burnish a burr.)
The burnished burrs usually last long time but I don't time them. Easily renewed with the hone and burnisher.

All sharpened by hand on a Wolverine platform. I make platform angle setting aids from plexiglass, quick and precise to use.

The reason I use the same angle on both sides is it lets me burnish a burn on one side or the other depending on what I want to use it on. I mark what is the TOP side for grab and use. I keep several similar NRS at hand but if I had just one and needed to use it on a different curve I would take off the burnished burr with an extra-fine diamond hone, then burnish a new appropriate burr. Works for me. I've made several just like these for friends who wanted one after using mine.

The reason I use this profile, a long curve on the side, straight on the top, is the curve works very well for curved areas, inside or outside, and the flat is useful for straighter sections, such as on the nearly flat wings when "turning air":



I do make some with a long side grind and a more traditional curved tip, used less often.

A few of the many other NRS I keep handy, a variety of sizes, radii, some angled to get into tight corners. On most I grind a different shaped NRS on the other end - never put them in handles. I never measure the angles, just guess and grind, strop, burnish, and try. Some are round Thompson stock (1/4 and 3/8"), some scraper stock, the one in the center of this pic I ground from a Thompson shallow detail spindle gouge - a different grind on the other end. Some angles work better on somethings than others so having a variety on hand is a big plus.

I could measure some angles but they might change.



JKJ

 

[Joel Daniels]

I grind the top to 20 degrees and the bottom to 60 degrees. Reason is that I have one wolverine rest set to 20 degrees for my skews and another rest set at 60 degrees for my regular “French curve” scrapers. They usually stay on my grinder - so I don’t have to set angles all the time. Then I normally only sharpen the bottom for the burr - I don’t pull a burr. But, I’m not an advanced turner and rarely pull a burr choosing to use the burr off the grinder.

 

[Doug Freeman]

I use 30/30 so each tool is ambidextrous, and I have quite a few sizes and shapes. If making “heavier” cuts I’ll use the grinder burr, then hone and burnish a burr. “Finish” cuts are done with a burnished burr. I use an 80gr stone wheel to sharpen.

 

[Bill Blasic]

I use no burr regardless if it is just a one angled or a NRS scraper and I use it until it no longer gives me those floating wisps. I'll then use a diamond hone once or twice before taking it back to the grinder. The HSS steel one next to the Powermatic has not been sharpened for about 3 years right now as turning has been interrupted by the CNC machine, the lasers, the 3D printer, the Rose Engine and the Lathe Engraver. The goal being that all 6 machines used to make 1 turned piece.

 

[Odie]

I don’t think most burrs last more than 30 seconds of turning. Probably easy to assess.

True, however that usefulness longevity is lengthened by the mental acuity required to "feel" the cut.....and progress along the length of the available burr, thus utilizing more of the capability that edge can provide. By cultivating this metal acuity, the time a burr is still useful can be extended significantly.....

=o=

 

[Mark Jundanian]

According to a Stuart Batty article I read a few years ago the optimum included angle for a NRS is about 70*. For me I like the idea of top and bottom grind angles to be the same for simplicity. So that would be 35* top and 35* bottom. Unfortunately that requires a lot of regrinding of my existing scrapers, so I haven't gotten there yet.

 

[robo hippy]

Well, my whole point about the different angles is to get the burr to last longer. No, it is not simple if you have standard grinder rests, but I like Joel's idea of having 2 platforms to work with, because that does make it more simple. On the skew chisel type, that burr may last 30 seconds. I can use mine for a couple of bowls, not just one, which I consider to be a result of having the steeper angle under the burr. They are not ambidextrous. I do have a specialized one for inside my recesses, which is "left handed". I did chat back and forth with Tim or Tom Wirsing, who is an expert with the NRS, and one comment sticks with me, that if you have to push at ALL to get it to cut, then it is dull. The madrone I have been turning is one of those woods that cuts well no matter what tools you are using. I still use a shear scrape on the outside, which I think leaves a better surface than the NRS, and a NRS on the inside, mostly because that is easier than using the shear scrape on the inside of the bowl. I start sanding at 150 on them, most of the time. This is due to the wood being madrone, and I have gone back to the LDD soak. The NRS does work on side/bowl grain, but it is still a scraper so it will pull a bit at the fiber. On end grain, I can get surfaces that 400 grit just roughs up. I use them for final cuts on my boxes.

robo hippy

 

[Mark Jundanian]

Well, my whole point abou

If I recall the Batty article, he said that with a greater included angle the burr lasts longer, but is not as sharp. Conversely a smaller angle gives a sharper, but shorter lived burr.

 

[John Kananis]

@Mark Jundanian I read that same article. I also own the Ashley Harwood video series where she gives the same advice. Apparently, anything over 70° leaves a less desirable finish (comparatively speaking) and loses the burr faster.

I haven't reached for a traditional scraper in quite some time as the nrs is good for far more than just removing tool marks (I've already converted my smallest round noise - maybe the rest will follow). Steve Jones inspired me to try it and I can't find a reason to go back. You can do anything a traditional scraper accomplishes with less effort, less tool mass and less leverage (including hollowing and even rounding in some cases). Go ahead and bring up shear scraping, the nrs can also be used in this orientation and gives a better finish on the super rare occasion that using it flat didn't make things look just right.

I have a 20° top bevel and 40° bottom bevel so that I can use the same platform (for the bottom) as I use for most of my gouges. On my main grinder, I have 4 platforms.: 3 are marked and tightened down to 17.5° (skews), 40° (nrs and most gouges but I'm considering changing my spindle gouges to 30°), 60° for bottom bowl gouge and traditional scrapers and 1 not set so I can get those odd things.

I've found that with nrs, how much burr you need depends on what you're doing. If I'm touching up tool marks, I sometimes let the grinder keep spinning while I work, other pieces work just fine with a burnished edge and you can hollow forever with just the smallest burr.

Here's a pic of what I use. The spear point is a little too spear 'pointy' so I'm considering changing the first half to a more obtuse angle - but it works great like this for adding detail!

Great topic btw, looking forward to seeing more responses.

 

[Asher Langton]

According to a Stuart Batty article I read a few years ago the optimum included angle for a NRS is about 70*. For me I like the idea of top and bottom grind angles to be the same for simplicity. So that would be 35* top and 35* bottom. Unfortunately that requires a lot of regrinding of my existing scrapers, so I haven't gotten there yet.

At the Symposium this year, Stuart said he sharpens his NRSs to a 40° included angle, 20° on each side.

 

[Mark Jundanian]

Wow. That's like a skew at that point.

 

[John K Jordan]

According to a Stuart Batty article I read a few years ago the optimum included angle for a NRS is about 70*. (Mark) At the Symposium this year, Stuart said he sharpens his NRSs to a 40° included angle, 20° on each side.

A good illustration of how people change their procedures. Or in some case, use any procedure that will work. In my experience with a bunch of NRS the included angle makes a difference but is not critical unless it's over 90 deg. The larger the angle, the more important the burr.

Skew-like NRS with small included angles like that can be used in a pinch even without a burr, handy if you need light scraping in a spot where the long point is on the wrong side. I used a small one yesterday on a tight spot while turning African Blackwood.

Wow. That's like a skew at that point.

I've heard professional demonstrators (turning bowls) hold up a skew and say besides using it as an NRS the only other thing it was good for was opening paint cans. I assume that was a joke since a paint-can opener or even a screwdriver would work far better. Regardless, for me their credibility dropped a notch.

JKJ

 

[robo hippy]

Hmm, considering the card scrapers, I am not convinced about the included angles yielding a sharper burr. I may have to experiment some more. A burnished burr on a card scraper is razor sharp. I know Sorby had a "hardwood" bowl scraper that appeared to have about a 70 or 80 degree main bevel. I suppose that would work on some "hardwood" bowls, Madrone may not be the best wood to use the NRSs on since it cuts so well. One wood that never seems to get a good finish surface with the NRS is big leaf maple. I had some myrtle this year that was very nasty. The cleanest surface I could get was with a gouge. Shear scraping and NRSs did rough it up, not make it cleaner.

I do use the Big Ugly tool for all of my heavy roughing cuts on bowls, both dry and wet wood. I consider it to be far more efficient than a gouge for removing bulk. If for no other reason, I sweep it side to side rather than start at the top, push in towards the bottom, then take the tool off the wood and come back to the top.

robo hippy

 

[Richard Findley]

For what it’s worth, I grind mine with 35° on each bevel. My bevels are usually of similar length but I don’t think that’s particularly important. I raise a burr on my grinder (8” slow running with 180 CBNs) then use a HSS rod to roll/burnish the burr like you might con a card/cabinet scraper.

IMO having different angles on the same tool is very inefficient, but I’m approaching things as a production turner!

Richard

 

[robo hippy]

Richard, the efficiency depends on the platform you have for your grinder. It takes all of 2 seconds to change angles on my robo rest, and the angles are EXACTLY repeatable. I did production work for most of the last 30 years, but only do one show a year now. To date, no one has wanted to reproduce my grinder rest.

View: https://www.youtube.com/watch?v=cUs4KYbpLOE


With this set up, no problem. I was thinking about the Duax angle platform from Woodpeckers, look that one up. It should be easy to convert the main principal behind it for a freestanding platform. Not sure if the Oneway Wolverine set up will be as easily adaptable. No patents on it, mostly because of the expense, and also, it is nothing other than a protractor. I quit making them because that business was taking up all of my play time. I do ALL of my sharpening on platforms. Far faster than using jigs.

robo hippy

 

[Richard Findley]

Richard, the efficiency depends on the platform you have for your grinder. It takes all of 2 seconds to change angles on my robo rest, and the angles are EXACTLY repeatable. I did production work for most of the last 30 years, but only do one show a year now. To date, no one has wanted to reproduce my grinder rest.

View: https://www.youtube.com/watch?v=cUs4KYbpLOE


With this set up, no problem. I was thinking about the Duax angle platform from Woodpeckers, look that one up. It should be easy to convert the main principal behind it for a freestanding platform. Not sure if the Oneway Wolverine set up will be as easily adaptable. No patents on it, mostly because of the expense, and also, it is nothing other than a protractor. I quit making them because that business was taking up all of my play time. I do ALL of my sharpening on platforms. Far faster than using jigs.

robo hippy

Yes, I’m all on platforms. I picked up a Right Angle platform at the Symposium which is much easier and quicker to adjust than my old one and would make having two angles on one tool more efficient but still seems like extra hassle when equal bevels work so well.