Well, thanks a lot folks. Now I burr envy. And possibly kangaroo envy. I can't look at my burrs straight in the eye now and have added the veritas burnisher to my Christmas list.
"Burr", the non-productive waste metal left on an edge after a bevel grinding process (this could be on a bench chisel, plane iron, meat knife, etc.) You can feel this ragged surface with your finger. It's deformed metal that is not completely ground off yet, or (possibly, as the internet once told me) sparks that travel back around and seize themselves to the tool surface. Either way, it's junk.
If someone missed it before, this picture shows a few of the curved hand scrapers I can't be without. I rough shape the curved card scrapers on a belt or disk sander, final shape and preliminary sharpening with a 600 grit CBN, then go through a few steps to prepare for and create the burnished burr. Note: while some recommend creating the curve edges with a grinder, in my experience a belt or disk sander creates MUCH less heat.
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The two at the upper left are 1/8" thick hardened steel StewMac scrapers, often used by luthiers. These are sharpened in an entirely different way, used without any kind of a burr. The depression machined in the middle makes them very easy to grip.
StewMac Ultimate Scraper - StewMac
The best tool for smoothing and shaping archtops, and a great all-around scraper.www.stewmac.com
If you haven't tried card scrapers like this, you may be quite pleased. Just say "no" to power sanding! Here is one in use on one of my pieces. After scraping these curves smooth, the wood usually doesn't need sandpaper coarser then 400 or maybe 320. (This sanding is done by hand - no power sanding.)
Here's the link to Lost Art Press/Crucible Tool, maker of that card scraper. All the tools Crucible makes are USA-built. At the bottom is Chris Schwarz's (company owner) video showing his scraper sharpening method, and his thoughts on his scraper profile. He admits, you should shape them to fit your purpose. There certainly are a hundred different ways to sharpen them.I threatened to report back about the Crucible hand scrapers I linked to earlier.
Gouges - To Deburr or Not to Deburr, that IS the Question!
I've been on a little journey to clean up and make usable an oldish rusted(ish) out hand plane. First hand plane, and its been a fun little project getting this thing ready to go so far. In my journey, I've been learning how to sharpen the iron, and deburring is a key part of the process (Paul...www.aawforum.org
I ordered a couple to evaluate and they came today. The steel seems good and the starting curved shape is reasonable. First thing I did was reshape one end of one to the way I prefer. I sharpened and burnished and it scraped well.
Here are those I got; the end of the one in the front is what I rounded. I shaped it with a coarse disk/belt sander followed by a 600-grit CBN wheel. (I'll probably reshape shape one or both sides later.)
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These seem to be made with quality steel. The "bluing" is not quite perfect. I'm sure they will be fine. I'll probably reshape the other and give it to a friend.
For hand scraper fans, the little block on the right, combined with the diamond hone, is an idea I got from, I think, a Fine Woodworking magazine article. The diamond hone fits crosswise in the bit slot on the top, held firmly in place with my finger - the scraper slides in the narrow slot. The combination makes a nice, smooth 90-deg edge without resorting to hand filing as usually recommended for cabinet scrapers.
The Arno burnisher is at the upper left in the photo. It easily put the needed burr on the scraper.
From what I've seen so far, I'd recommend them to woodturners for bowls, platter, and more. Having the sides pre-rounded sure saves a bunch of work compared to what I'm used to: starting with a rectangular cabinet scraper.
JKJ
I might be misunderstanding you, but the burr is what does the cutting on many edges. I saw a guy from Montana Knife Company on a podcast talking about sharpening knives. He said that the very fine burr created by sharpening is what actually does the cutting. You can't feel the burr on a knife, but it's there. His words (paraphrased) not mine.
No problem, that makes a difference. Thanks for running it down. Now I have something else to watch and learn from!Here's the video cued up to that bit. He said, "fine serrated edge" not "burr". My bad.
No problem, that makes a difference. Thanks for running it down. Now I have something else to watch and learn from!
(But first gotta go feed the peacocks, llamas, and horses and change the cutoff solenoid on a diesel engine....)
I'm not knocking the Montana Knife guy but I'm inclined to disagree with that, based both on my observations and testing of knife edges after shrapening on my knife sharpening (belt based) machine. Skipping the final honing belt which removes any trace of a burr makes a difference, and not for the better.
We usually test by 1) how easily and cleanly the knife can be drawn through a consistent piece of paper held in the air between finger and thumb (paper is from a yellow sticky note pad - an uncalibrated subjective test but which has proven over the years to be relatively consistent), and 2), with the Edge On Up PT50 tester which measures the force needed to cut through a calibrated strand. They suggest testing with a razor blade. I like to compare my sharpened edges to a new #11 scalpel blade (which I buy 100 at a time - never know when you might need to do surgery on something on the farm).
A third test is seeing if it cuts arm hair as well as a razor blade, but that's also a subjective test best used after honing lathe tools at a demo. The edge under the microscope does show if there is a tiny burr or not.
However, the podcasting Montana Knife guy, like everyone, is certainly entitled to his opinion. But having worked on a variety of R&D projects, given the choice, I tend to respect opinions better when backed up something verifiable. Maybe one person's "sharp" is another person's "almost sharp."
There is no knife that I know of that benefits from a burr
There is no knife that I know of that benefits from a burr, but knives that are used to slice benefit from micro-serrations at the very cutting edge and honing and buffing that edge can reduce its performance as a slicing knife.
The definition of a burr is the real problem. My definition is the thinnest leading edge of a blade which has been deflected from a straight line from the spine. Cooking knives we steel to push the burr back inline with the blade, or if it's thin enough, break it off leaving the remainder of the steel inline with the spine.
Cooking knives we steel to push the burr back inline with the blade, or if it's thin enough, break it off leaving the remainder of the steel inline with the spine...cooking knives we steel to push the burr back inline with the blade, or if it's thin enough, break it off leaving the remainder of the steel inline with the spine... Generally 'cutting/slicing knives' can be sharp, but the burr is so extreme the edge is rounded over. Steeling the otherwise sharp knife brings it back to top performance in seconds.
I’ll have to try the cigarette paper. Where do you get it? I used to know back in the ‘70s…
I’ll have to try the cigarette paper. Where do you get it? I used to know back in the ‘70s…
I did a test some years ago with my bowl gouge. The first is straight from grinder with 180 gr CBN. Second is honed on the inside. Third is honed on both inside and outside. As I always power sand I settled for only honing inside.
Talk about "Duh!" moments. I'm hacking up a little chunk of ash with a scraper, thinking it was time to dress it up with a fresh hook edge from the Veritas burnisher. Then I thought to myself, I should mount it to a block to set in the bed gap, like Bill did. I turn to my right to scrounge a lump of wood to make a block, only to find my bench vise staring at me 3' right of the lathe. Problem solved, no need to look for that block of wood now.I bought a Veritas Carbide rod and made the rest. It sits snuggly in the ways of my lathe for immediate use as needed. You can press a fairly large burr if needed with it mounted this way.
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Underside.
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You don’t need to. The copies, like the Wen version, will do just as well when used with tormek jigs. Been using the tormek jigs on the Grizzly version for a dozen yrs.I don't think I could afford the Tormek system. Would LOVE one, but its just out of reach right now.
To build upon this visually, Tomislav Tomasic has a great piece of video where he uses his method of raising a hook edge on the scraper with a burnisher (he still calls it a burr...). His burnisher is hand-held (and I've not seen his method, I'll have to try it) vs jig mount like the Veritas. In the end, they both get you to the same spot. This u-toob link should get you within a few seconds of where he explains it (around the 25:30 mark)-"Burr", the non-productive waste metal left on an edge after a bevel grinding process (this could be on a bench chisel, plane iron, meat knife, etc.) You can feel this ragged surface with your finger. It's deformed metal that is not completely ground off yet, or (possibly, as the internet once told me) sparks that travel back around and seize themselves to the tool surface. Either way, it's junk.
"Hone", the process of removing said waste metal by alternately stroking an abrasive honing device flat across both bevels, which define the edge, until the waste is gone.
"Hook", sometimes mistakenly called a "burr edge", which is the result of using a hardened steel burnisher to deform (or "roll") an edge into a new micro bevel plane. You can feel this very uniform raised hook with your finger. Careful not to cut yourself.
When a scraper has no burnished hook on it, you are scraping (tearing) the wood fibers away from each other. When a scraper has the burnished hook at the line where the two bevels meet (the edge), you now have a new cutting edge and you are shearing (cutting) the fibers away from each other as the micro bevel rubs the wood and supports the cutting edge of the hook. A cabinetmaker's card scraper depends on this hook edge, resulting in surfaces that require no sandpaper.
Ground burr edge= sawdust.
Honed and burnished hook edge= whispy shavings that just float away.
Sure, you can "cut" with the grinding burr on a scraper, for a couple seconds until the wood breaks away that waste metal. Or, you can actually cut with the rolled/burnished hook edge for a much longer time (relatively speaking), and when that hook "dulls", or gets bent back down to the original edge shape, then your burnishing tool can quickly re-establish the hook with a few strokes.
None of this is new science, it's the way scrapers (in particlar, and skews just to remove the burr waste) have been properly sharpened... forever. Probably more typically done in the days of plain carbon steels vs. today's super steels. None of this is really necessary with today's super steel gouges. Most just take the gouge from the wheel to the wood, because that tool has an "adequately strong and sharp" edge for gouge cutting the wood, even if the burr waste is momentarily present. Scrapers and skews benefit from burr removal.
Burnishing historic carbon steel (and even M2 HSS) is quite easy for the Veritas burnisher, and others, to accomplish. But a burnisher shall be harder than the steel being burnished, or it can't work. If you have a scraper made from super hard space age steel, any burnishing tool will have limited to no effect on reshaping that edge into a hook.
(Ring goes the bell...) Okay, Class, there will be a quiz on Monday covering this material. Ha!
After experimenting with various methods, for years now I’ve always burnished a burr by hand: conventional turning scrapers, NRS, and (mostly curved) hand-held scrapers. For me they work well and hold up longer than either the grinder or honed burrs.His burnisher is hand-held (and I've not seen his method,
John when you are burnishing, are you using a jig device like the Veritas plate burnisher, or holding a burnishing rod freehand like Tomislav demonstrates?After experimenting with various methods, for years now I’ve always burnished a burr by hand: conventional turning scrapers, NRS, and (mostly curved) hand-held scrapers. For me they work well and hold up longer than either the grinder or honed burrs.
JKJ