Oh no, more experimenting ahead...

[robo hippy]

I got to see Eric Lofstrom last night up in Salem, OR. While we do some things similarly, his approach to the NRS (negative rake scraper) is considerably different than mine.... It came up a while back about me seeing some one who had a small carbide rod, maybe 1/8 inch in diameter, inserted into a wood dowel, and was using that for burnishing his burrs, well, that was Eric. "I was with Bonnie Klein once and told her that I used a NRS for heavy roughing. She didn't believe me, but I was taking off 1 1/2 inch wide shavings." Hmm, I can do that with my standard scrapers, but with a NRS? My attempts with burnished burrs on the NRS and my standard scrapers left a lot to be desired for a good cutting edge. Well, I went out to the shop, found some carbide drill bits that some one gave me a long time ago, drilled a hole in some drill rod, inserted the bit, and tried it.... Having the NRS sharpened on a 600 grit wheel took most of the wheel burr off, and I just took a few short strokes. Very good turned burr! So, I have to try it with all my scrapers......

Eric is an elementary school teacher, so his presentations are very well done. If you ever get the chance to see him, don't miss the opportunity. His dad is/was an engineer like mine, and we both suffer/enjoy the engineer's syndrome: If it ain't broke, take it apart and fix it anyway!

I really wish there was a way to get 20 or more of us together for a play date, exchange tools, techniques, ideas...

robo hippy

 

[Jamie Straw]

Eric was our presenter last month, subject = understanding and using the skew. He is an excellent presenter, very organized, fun to listen to, open to questions. He is a PE teacher mostly, if I remember correctly, but previous to that career was focused on a field that required a good eye and understanding of body mechanics, which he emphasizes in teaching wood turning. Reed, LMK if your group starts to come together. If it's not snowing, I might make it down.

 

[Jamie Straw]

Well, I went out to the shop, found some carbide drill bits that some one gave me a long time ago, drilled a hole in some drill rod, inserted the bit, and tried it....

Picture? Pleeeeze??

 

[robo hippy]

Jamie, if you go to his sharpening article, he has a picture of his on the bottom of the page. I just turned a small dry madrone piece, and I could realistically start sanding at 320 or even 400.... Odie, watch out, I may get one out where I can start sanding at 600. This really puts a remarkable edge on scrapers. All of his are NRSs'.

http://www.ericlofstrom.com/resources/

robo hippy

 

[Odie]

Jamie, if you go to his sharpening article, he has a picture of his on the bottom of the page. I just turned a small dry madrone piece, and I could realistically start sanding at 320 or even 400.... Odie, watch out, I may get one out where I can start sanding at 600. This really puts a remarkable edge on scrapers. All of his are NRSs'.

http://www.ericlofstrom.com/resources/

robo hippy

Well......you've got my attention, Robo!

Refining the tool to the point where it's capable of that kind of a precision cut is half the battle......of course, refining your technique is the other half.

1/8th inch diameter is pretty small. Can I assume your carbide drill bit inserted into a dowel is hand held to produce the bur?

I should clarify that starting at 600 for sanding is something I've only done a couple of times.......and, all the moons and stars need to be in alignment for that to happen! If you're starting at 320/400 with any consistency, then you are doing great!

You know, I've never played around with NRS to any extent, and I've been doing all my finest cuts with a standard scraper with a raised bur produced on the Veritas. Tell me if there is something I'm not getting......because it sure seems to me like the presentation of the NRS can be exactly the same as a standard scraper, by simply adjusting the presentation a little. It seems like the same cut can be done either way, but the NRS is a little more complicated, with it's two bevels.

......or, is it that the NRS is primarily used flat on the tool rest? My best cuts are done with the scraper angled on the tool rest, in a shear scrape mode. Now, if we're discussing flat on the tool rest, then I can see where a NRS might have some presentation advantage over a standard scraper, also flat on the tool rest........

Your thoughts please.........

ko

 

[chrisdaniels]

the nrs is always flat. you can however use it at a sheer angle but I haven't found it to be significantly better or worse. it's just easier to control and easier to get the sweet spot with a nrs, IMO
<----Not a professional

 

[hockenbery]

the nrs is always flat. you can however use it at a sheer angle but I haven't found it to be significantly better or worse. it's just easier to control and easier to get the sweet spot with a nrs, IMO
<----Not a professional

Did you get a word wrong somewhere? You seem to contradict yourself.

Maybe we shear scrape differently.
Whe i use a scraper To shear scrape I put the tool edge on the tool rest and the top of the bevel edge pointing at the surface of the wood.

 

[robo hippy]

I think the refined edge is the key. Yes, MOST of the time, the NRS is flat on the tool rest. With the standard burr off the grinder, it doesn't last long enough to give you any benefits. With the burnished burr, you get a long lasting edge that is very sharp, and you can bend it over and then stand it up again a couple of times before going back to the grinder. I did a tiny bit of work on a hard maple finial yesterday with a shear scrape NRS, and it left a nice polished surface. Difficult to rub the bevel, but possible. Just preliminary now, but it seems that a 70/20 NRS is much more difficult to raise a burr on than a 30/30, mostly because of how blunt the angles are. I haven't used the Veritas burnishing tool so can't compare, and have to go out and try to burnish one of my heavy roughing scrapers, Big Ugly included. I am doing this by hand. I would think that if I made a 1/8 inch rod into some thing like the Veritas tool, it would snap off. Aren't the pins on the Veritas tool 1/4 inch? For hand held, I think size matters, and that is why the 1/8 inch one turns a pretty good burr. I noticed a long time ago that I could get a better burr with my triangle burnishing tool than I could with the round one, most likely due to the triangle having a smaller surface on the bevel edge. I am not using much pressure, just a kiss. I am starting with bevels that have been sharpened on my 600 and 1000 grit CBN wheels too, so no hand honing. I may try honing on flat stones as well, just to see.

robo hippy

 

[Odie]

I think the refined edge is the key. Yes, MOST of the time, the NRS is flat on the tool rest. With the standard burr off the grinder, it doesn't last long enough to give you any benefits. With the burnished burr, you get a long lasting edge that is very sharp, and you can bend it over and then stand it up again a couple of times before going back to the grinder. I did a tiny bit of work on a hard maple finial yesterday with a shear scrape NRS, and it left a nice polished surface. Difficult to rub the bevel, but possible. Just preliminary now, but it seems that a 70/20 NRS is much more difficult to raise a burr on than a 30/30, mostly because of how blunt the angles are. I haven't used the Veritas burnishing tool so can't compare, and have to go out and try to burnish one of my heavy roughing scrapers, Big Ugly included. I am doing this by hand. I would think that if I made a 1/8 inch rod into some thing like the Veritas tool, it would snap off. Aren't the pins on the Veritas tool 1/4 inch? For hand held, I think size matters, and that is why the 1/8 inch one turns a pretty good burr. I noticed a long time ago that I could get a better burr with my triangle burnishing tool than I could with the round one, most likely due to the triangle having a smaller surface on the bevel edge. I am not using much pressure, just a kiss. I am starting with bevels that have been sharpened on my 600 and 1000 grit CBN wheels too, so no hand honing. I may try honing on flat stones as well, just to see.

robo hippy

OK, keep us posted on your experimenting, robo.....

Yes.....without going out and measuring, the Veritas pins are close to 1/4" diameter, and taper to a cone shape. There are now two different cone angles with the pins supplied with the newer Veritas jigs. At the top of the cone shapes, the diameter is probably close to 1/8". It would all depend on the user's grind angle, to which pin would be the preference. A more acute angle would require less pressure to create the bur, while the opposite would be true, too. I'm assuming the original thinking is the cone angle would be a consideration for forming the bur, depending on an individual's needs and tool angle grinds. At times, I've used the Veritas to greatly leverage the pressure to create the bur......and, have never broken one of the carbide pins. It seems they can handle quite a lot of pressure. The more obtuse the angle of the scraper grind, the more pressure it takes to create a usable bur.....

You are right that a ground bur wears more quickly than the formed, or raised bur. I'm still using both, because the ground bur is so much easier and faster to create, than the raised bur. I do, almost exclusively use the raised bur for the final finishing cuts, prior to sanding, while the ground bur is more applicable to initial roughing and shaping.

ko

 

[chrisdaniels]

I haven't tried burnishing but it seems like it would take significantly more time no? I just recieved a can of yorkshire grit and it says you only have to sand up to 220-240 then use the paste and it takes it to the equivalent of about 1000 grit sanding. haven't tried it yet as i'm in the finishing stages of the new lathe stand featured in http://www.popularwoodworking.com/projects/ultimate-lathe-stand by alan lacer. It is to replace my giant bulky frankenstein stand that I threw together when I got my lathe. as soon as it's done I'm looking forward to trying this yorkshire grit out.

 

[robo hippy]

I did try my triangle burnisher, and the edges looked like some one had been chewing on them.... took them back so smooth and they worked better. Still not positive about prepping the NRS for burnishing. Most of the time I have been going to the 600 grit wheel. No idea about honing as my main stone is 600 grit. I did take it to the flat side of my 1000 grit wheel once, and need to try some more. I turned a piece of wet ambrosia maple, and like all soft wood and any type of scraper, it didn't cut as cleanly unless I used a shear cut/scrape, but I still got a nice 'off the tool' finish. The burr did tend to clog up, and if I turned it down, then back up, it didn't seem to cut as well. I did try a nice piece of madrone and got a smooth as butter finish. II kind of think I need a production run and then try all the different techniques.

My carbide tipped burnisher is looking polished now just from use. I do think it does a better job of burnishing than the standard burnishing tool.

Not sure on comparisons on actual time used for burnishing. Straight off the 600 grit wheel, turn the grinder burr down, burnish the burr back up is fairly simple. Biggest question for me is how much time does it save in sanding. Thus far, it has been 1 to 3 sanding grits, so rather than starting at 100, I am at 120 to 180 for first grit. The wet wood turned to final thickness will tend to oxidize, and hard to figure out if I need to sand off the 'patina' which almost always requires 100 grit, or leave it kind of splotchy, which can be done with 120. Again, dry wood cuts cleaner than wet wood.

robo hippy

 

[Odie]

I haven't tried burnishing but it seems like it would take significantly more time no? I just recieved a can of yorkshire grit and it says you only have to sand up to 220-240 then use the paste and it takes it to the equivalent of about 1000 grit sanding. haven't tried it yet as i'm in the finishing stages of the new lathe stand featured in http://www.popularwoodworking.com/projects/ultimate-lathe-stand by alan lacer. It is to replace my giant bulky frankenstein stand that I threw together when I got my lathe. as soon as it's done I'm looking forward to trying this yorkshire grit out.

Chris......I've never heard about Yorkshire Grit:
http://yorkshire-grit.com/Product-Page/
http://www.thewalnutlog.com/yorkshire-grit/

I am interested in evaluation from those who have used Yorkshire Grit........

Is this something that will leave a residue on, and in the wood?

 

[chrisdaniels]

it is a mixture of waxes and oil with pumice and rottenstone in it. Has basically no smell at all. you rub it on and with a clean paper towel you turn the lathe on and basically work it in like wax which wipes off any residue as you go then they say you can apply your finish of choice over it. I'll post pics and everything when I get a chance to use it. I have a couple of pieces of dry platter blanks that I can try it on.

 

[MarkAndrews]

Chris, I'm really interested in your impression of the Yorkshire grit, not only it's effectiveness, but did it present any issues when finishing? I'm curious what finishes you have tried after using it.

 

[Fred Belknap]

You know, I've never played around with NRS to any extent, and I've been doing all my finest cuts with a standard scraper with a raised bur produced on the Veritas. Tell me if there is something I'm not getting......because it sure seems to me like the presentation of the NRS can be exactly the same as a standard scraper, by simply adjusting the presentation a little. It seems like the same cut can be done either way, but the NRS is a little more complicated, with it's two bevels.

Odie I use NRS and one of the biggest advantage is that it is almost impossible to get a catch. I don't use them to rough out or to do the initial cutting on a rough out, but use them to finish almost every bowl I do. The can be use flat on the toolrest or above center or below center with a little pressure or a lot of pressure. I do mostly NE bowls and you can take extremely light cuts on the wings. It cuts slow but I would rather use them than sandpaper.

 

[robo hippy]

Look up Mike Waldt on You Tube, he really likes it. Nice gent. Welch. Good videos.

robo hippy

 

[Bill Boehme]

I haven't tried burnishing but it seems like it would take significantly more time no? ....

No. Maybe five seconds if you you aren't in a hurry.

 

[Jon Murphy]

I just fell into this thread (couldn't resist the word "experimenting" in the title). I don't use a scraper very much, although I do shear scrape with my fingernail gouges. I don't understand the difference in the mechanics of the NRS vs. the standard scraper, particularly when you add the burnishing.

Allow me to describe my thoughts. First may I say I use the Veritas burnisher rather than a hand burnisher. All the instructions I've seen for hand burnishing of a standard scraper say to burnish at a "back angle" of about 5 dgs., while the Veritas makes a "forward angle" of 5 to 10 dgs. (depending on the pin used). I agree with Robo that it is the refinement of the burr that makes the difference, but must point out to him that Waldt is Welsh, not Welch (welcher is an unfortunate word from when the English looked down on the Welsh <g>). For that reason (the refinement) I always hone off the grinder burr and go to the burnisher.

Oops, also for Robo.The Veritas pins are 1/4", but they are tapered above the socket so the effective diameter is closer to 1/8" (it varies by the thickness of the scraper).

Now to the question. It seems to me that the fineness of the "cut" should be related to the angle of the burr to the bevel - assuming you work the tool with the bevel close to "rubbing" - rather than the angle to the flat of the tool. I can see no reason for a difference between the standard scraper and the NRS as long as the tool is presented to the work piece with regard to the bevel. Oops, just though of one difference, but it only involves a Veritas type burnisher. On the Veritas, where the tool is flat on the plate, the burr on an NRS will be a "back angle" to the plane of the tool - while on a standard scraper it will always be a "forward angle". With hand burnishing the angle is the one you choose (but not as consistent, unless you have better hands than I do).

I'm confused, without a lot of experimenting I don't know what I'm trying to accomplish (aside from a smooth result).

 

[john lucas]

Jon The difference in a NRS and standard scraper is more than the burr. It's how it reacts with the wood. A negative rake scraper puts lets pressure against the wood. I thought for a while that a regular scraper tilted up so the top surface was the same angle as a negative rake scraper would cut the same way. However when you play with thin natural edge bowls you get less chatter with the negative rake scraper than a flat scraper held at that same angle. My guess is that it's the tilt on the tool rest. The wood must pull the flat scraper into itself where the negative rake scraper has the forces pushed straight down on the tool rest.
If I use both tools in a shear scrape position there isn't any difference that I can feel. Probably because the burr is presented at the same angle and the forces down on the tool rest are the same.

 

[Emiliano Achaval]

Why would you want to rough turn with a NRS??I can think of several better tools to rough turn, where I'll be cutting... I have several NRS, all sizes, they are all for finishing.