Sharpening scrapers up-side-down

[Norm Zax]

I use a regular grinder for sharpening my tools, on an 80 grit white stone, using home made jigs. On a video by Jimmy C (nice guy, isny he?), he mentions sharpening scrapers up-side-down to create a bur. As much as I tried, turning the scraper around forces me to introduce the tool to the stone at such an angle that it will most probably be snatched from my hand and zoom off. Its about 70 degrees to the table.
Am I doing something wrong? Anyone have a solution for a homemade jig?
thx,
Norm

[David Walser]

Try this: Assume you've sharpened your scraper the regular way (right-side-up) with a bevel angle of whatever you like. Then, flip the scraper over and just barely kiss the top edge (now the bottom edge) against the grinding wheel. You'll create a small micro-bevel. It'll be at the "wrong" angle, but you shouldn't care -- you're just after the small burr that'll be created by the wheel rotating towards the top edge (now the bottom edge) of the scraper. You can readjust the grinder's tool support if you like, but you shouldn't need too. All you're after is the grinder just barely touching the cutting, err, scraping edge -- not the entire bevel.

Note: I just attended a demo by Bonnie Klein at which she said she no longer uses a burr on her scrapers. Instead, she hones off the burr created by grinding and claims she gets better results with fewer catches. Tormek also claims a scraper without a burr cuts more cleanly on end grain. Like all things in turning and most things in life, YMMV.

Hope this helps.

[Ben Gastfriend]

I agree. I got rid of the burr on my scrapers, they were causing me too much trouble. They work just as well (if not better) without it.

Just my 2c.

[Dale Gregory]

In a recent demo by Professional turner Alan Stirt he also removes the burr with a fine diamond sharpener, but then gives it a few swipes from the other side to put just a very tiny burr as he calls it back on. I guess it all comes down to what you prefer, best to experiment for yourself.

Dale

[Jim Becker]

I use the grinder to sharpen a scraper, but don't worry about a burr most of the time. When I do want one, I use a Veritas burnisher that is mounted on the surface of my grinder stand and designed for the purpose. It will curl a consistent burr which is harder to get right off the grinder and since you can vary pressure, you can also varry the aggressiveness of the burr.

[Gordon Seto]

According to Stuart Batty:
Burr or not depends on material, no burr for hard dense material. Burr works better with soft material.
I believe Chris Stott also said the same thing.

[robert hainstock]

I place my burnisher straight up in a vise, and holding the tip of the scraper firmly against it, drag the tool tip across the burnisher. This usually creates a nice edge.
Holding a tool upside down against a grinder is arecipe for a big Oweeeee. :eek:
Bob

[Reed Gray]

I have always used a burr for cutting with my scrapers. I prefer them for all the rough out and shaping on my bowls. After all, when you use a gouge, you are using a scraping cut. I have found out that you can sharpen the scraper face up, face down, or even sideways and raise a burr. For some reason, the face up seems to raise the best burr for me, and the face down raises the weakest burr. Don't really know why, but in my experience, this is how it works for me. I have been using CBN (cubic boric nitride wheels) which last forever, and leave a finer edge than an comaprable grit aluminum oxide wheel, which could play a part in this result. I have tried to burnish a burr on my scrapers and don't like the results. I don't have the burnisher thing from Veritas. I tried a round burnisher that I use on my card scrapers (I do flat work), and didn't raise much of a burr. I tried the triangle burnisher, and raised what feels like a good burr, and it didn't cut as well as the one I get from grinding. When I refresh the burr, I first put the scraper upside down on a diamond stone to remove the old burr. I then put it right side up on a tool rest platform that is set at about 80 degrees (rather blunt, and I have never measured the exact angle). I apply pressure towards the wheel, and not down on the tool rest. This raises a good burr for me. I really need to try to remove the burr some time and see how it cuts for me, but I have to do some flat work for my next show in 2 1/2 weeks, so can't get to it for a while. How smooth of a cut you get, depends on the wood, and how much pressure you are putting on the tool. Softer woods are much more prone to tearout than denser woods. If I am really hogging off material, then there is more tearout. As I get closer to the final shape, I take lighter cuts. By the time I get to final shape, one pass with a gouge, removing about 1/16 of material will clean up all the remaining tearout.
robo hippy