Burnisher

[Captain Pete]

At a recent demo by a very prominent turner, he removed the burr on his scraper raised by the CBN wheel using a hand-held hone, then raised a new burr on the scraper using a bench-top burnisher. He told us that one of the reasons he does so is that a burr raised in that way lasts far longer than one raised on a grinder. Is that your experience?

[robo hippy]

I not sure about that one. The burrs I get straight off the wheel, from the 80 and 180 grit wheels are really heavy duty, and I use them for heavy stock removal when turning bowls. Way faster, for me, than gouges. They also do an excellent job of shear scraping, and the burrs from them work a bit better on wet wood than on dry wood. For the dry wood, I use the finer 600 grit wheel (I have a 1000 grit wheel too), which makes an excellent burr for tiny angle hair shavings from dry wood and leave an almost burnished look to some woods. I have not used that particular burnisher. I have hand burnished using the traditional card scraper burnishing tool. That does a good job of raising a burr, but I don't really know how that one compares to the Veritas set up which uses carbide rods. I saw one demonstrator who said flat out that it is impossible to hand burnish a burr on M2 steel because it was so hard... I do some times use the burnishing tool to turn down the burr before putting a new one on, as I like to remove the old one before refreshing. Some times I burnish the old one down, then burnish it back up, just to see what it does. Without honing it off and starting fresh, it works once or twice, but some times I think it is better to start new. A burr on my scrapers will last through one big bowl no problem. Maybe a bit better than any gouge I use. Like the gouges, I do like a fresh edge for finish cuts. Now, the Big Ugly tool, I can do all the roughing on several big bowls without needing to resharpen.

I guess that the 600 and 1000 grit wheels could almost be considered burnishing. When sanding wood, the really fine grits do more polishing and to some extent burnish the wood surface, but those wheels do leave a good finish cut burr, but not a good heavy roughing burr.

robo hippy

[MichaelMouse]

From the grinder, bits and pieces form the burr, sort of like a file, for analogy. Lots of little sharp edges to cut wood. A continuous edge, turned at a consistent angle can be used as a scraper or as a microplane, like a cabinet scraper. Its versatility certainly favors the burnished edge. An edge with no burr can also be used to scrape, but it may not be its best act. .

[robo hippy]

There are huge differences in the burrs from different grinding wheels, especially between more standard wheels and the CBN wheels. Main difference is a much more uniform and consistent burr from the CBN. It gets better the higher grit you use to sharpen them.

robo hippy

[AHill]

I use a CBN wheel for my grinding. There's not a discernible difference between burrs raised on my CBN wheel compared to the Lee Valley burnisher I have.

[robo hippy]

I was out playing with some myrtle/California Bay Laurel today and it was giving me fits... One piece works great with the big ugly, the next, not at all. One cuts great with a gouge, next, not at all...... I have found out that the 600 grit burrs do make for a much better cut if the burr is fresh. They seem to have about as much durability as a negative rake scraper. Oh, some times the NRS cut beautifully, some times not at all, and fresh, 600, or 1000 grit wheel, no difference... All of the pieces cut from the same log section too. Some times the big ugly in a shear scrape would do it, some times not. For sure though, I get much cleaner cuts on the dry myrtle than I do on the green... Just because...

robo hippy

[Wildwood]

I cannot tell the difference after using my Veritas scraper burnisher, hand burnisher and coming right off the grinder. Prefer using my grinder for my heavy duty scrapers. Do not have a CBN wheel.

[Arlin Eastman]

With the tools I have tried I am thinking it is true. A wheel bends over thin wire over the edge but when I use a carbide burnisher and I can make a thicker wire over the edge or thinner whichever is my choice. Matter of fact I have bent them way to much and broke off a piece before.

Arlin

[MichaelMouse]

He's right. As a couple posters here have mentioned, even grinding burrs left by finer grits - approximating a continuous turned edge - make finer cuts. Of course, the included angle between face and bevel determines some of the durability/usability of the grinding burr, even with the same grit in the grinder. You can turn the burr lightly, or heavily, sometimes so heavily that you break continuity on the edge, as Arlin mentions, then start over.

http://www.docgreenwoodturner.com/scrapers1.html
http://www.docgreenwoodturner.com/scrapers2.html
http://www.docgreenwoodturner.com/scrapers3.html

Pretty good throughout, though a few places may have you shaking your head.

[robo hippy]

Doc Green's stuff is a good read, and I have chatted with him a few times. For sure, this is from BCBN (before CBN wheels), and a bit outdated. The burrs from the CBN wheels last far longer than 15 seconds, and excell in removing huge amounts of material quickly when roughing bowls. I didn't rewrite the book on scrapers, more than anything, I rediscovered old ways to use them. Part of what I liked about seeing Fred Uggla and his use of the Big Ugly....

robo hippy