Burnishing a Scraper

Why wait. I use a heavy Phillips head screwdriver - round shank - clamp scraper in vise and burnish. Getting the proper angle is what the LV tool gets you. Patience and practice can get you that.

if that burnishing tool is the aluminum plate with a couple of pins sticking up, it works, but you could save $$ by just driving a couple of concrete nails into a board and using them - you don't need that tool to roll an edge on your scraper

And, you should probably avoid a scraper on the inside of bowls - it's a great way to get amazingly spectacular catches - much worse than using a gouge

I have tried both ways, and get more catches using a burnished hook. Maybe I need more practice.

Or not.... The key to scraping (inside or out) is a single, small point of contact. Real easy to get a long contact point (or even two) when inside (just like scraping the inside of a hollow form)

Personally I also often shear-scrape the final cuts

Well, I really wasn't asking about the product so much as the practice.

Is there much of a difference in how the tool cuts?

Yes, Burnish.

I borrowed one for a couple of weeks and wasn't impressed with the burnished "burr/ hook" produced.. Maybe if that was the way I learned to sharpen and use a scraper it would be very cool, but I'm back to my old method..

I've dedicated a 1" belt grinder to the scrapers... It's set at a negative angle so that I can put the scraper on the table "upside down" and rotate it across the belt.. This seems to put a bit more burr on the edge than doing it "right side up".. As always, YMWV

I find it a bit grabbier. I also will hit the grinder after burnishing a number of times. Just seems to cut better after being ground but the burnish is a quick way to get a burr/hook back on.

As mentioned, you don't need the Lee Valley device - try it w/a screwdriver or something first. If you like it, buy the Lee Valley burnisher. If not, nothing lost.

Test on a piece of scrap, or early on when you still have enough wood to recover if it misbehaves...

FYI (following up myself and replying again to Bill),

As I noted above, the key is a controlled point of contact. Yesterday I finished 5 bowls, all of them using gouges and scrapers, but scraping Not one catch in the process

and finished with shear-scrapes

Just musing,

I'm too lazy (read have forgotten how) to bother doing the math, but I wonder how many linear feet of wood a burr scrapes per sec. when it touches a bowl turning at any reasonable rpm. I doubt a fragile hooked burr lasts long on a wood-turning scraper, but there's no doubt that a burr seems to work for a period longer than expected. I wonder if the effects of a burr that last any time at all are really due to improving the edge and not the burr.

Anybody ever put a burr on the edge of a reversed ground bevel (on the concave side) of a gouge (preferably an unused cheap carbon steel spindle gouge) placed upside down with the wings resting flat on the tool rest. Should provide a fixed angle of attack and a small point of contact?? Much safer to do a thought experiment from my armchair and let somebody else try it ....or not.

Turn to Safety, Arch Fortiter

On Fri, 30 Sep 2011 13:07:59 -0500, Arch wrote (in message ):

snipped the other part of Arch's query

Let's see, now. We're dealing with a round thing, so that means we have to use pi and either a radius or a diameter. I always struggle with the choice, radius or diameter, so I get a little silly. One possible formula is Area equals pi R squared. (Or is it Area equals pi D squared?)Then I say to myself, "but that is silly, as everyone knows pie are round." In my world, then, I know the formula is correct, A=pi x R squared.

That means for me, then, that circumference is pi times Diameter, and now my dimensional choices are sorted out, and I can continue.

Surface speed will be an expression of the number of circumferences that pass by the tool rest in a second. Consider then a spindle 4 inches in diameter, turning at 300 RPM. In one second that spindle makes five turns (300 divided by 60). The circumference of a 4 inch diameter spindle is 12.56 inches (3.14 times 4). It is too bad that a key number for round objects is not a round number, itself. It makes things messy.

I digress.

At a rate of five circumferences per second, that means then, that the surface of the spindle is moving at 62.8 inches per second, or just a tad over five feet per second.

I'm a fairly sturdy guy, and can push a cabinet scraper with gusto, but I can not scrape a five foot board in one second. Depending on the species of wood I am scraping, and how much effort I am putting into that scraper, I might have to re-do the edge of the scraper a couple of times before I am done, and I am moving much slower than 5 feet per second. I am afraid that a hook edge scraper tool on a lathe will not have a long life before needing a re-do.

One of the advantages of a cabinet scraper in "flat" woodworking is its relatively broad area compared to a smoothing plane, for a final surface. In wood turning, the contact edge of a hook scraper will be short, and I think there is a likelihood of an uneven surface - a bunch of very fine and very smooth grooves, side-by-side.

Respectfully submitted for your consideration, tom koehler

I figure the burr lasts 10 or maybe 15 seconds, thats all

I know a demonstrator that advocates something like that. He takes a 2 inch SRG, grinds it to a finger-nail. Then, with the flute down, grinds a 70 degree bevel. When he is doing the finish cut on a bowl, he puts a fresh burr on the gouge (only the left side, with the flute faces down). He keeps the SRG level and cuts at a single point of contact

What's an SRG?

Spindle Roughing Gouge