A needlessly long musing about finish scraping. Right? Wrong!

Many of us came to woodturning by way of 'flat work' and had used cabinet scrapers on a relatively soft material. Also many of us came from the machine shop and had used hand scrapers on a relatively hard material. The softer wood required a small angle edge tool, the harder metal a large supporting edge angle, but both scraped not cut. The woodworker might follow his cuts with scraping then sanding & buffing, the metal worker by lapping & polishing, but both were abrasions.

Furniture and metal craftsmen are likely to consider a scraper to be a fine sensitive tool used to smooth & flatten the inevitable imperfections of _cutting. Not so for many woodturners. Some will consider my statement as heresy. Don't we all 'know' that a proper _cut will produce a superior turned surface? Well sometimes, as in hollowing end grain or gouging out a bowl's insides, but right or wrong, I'm musing about _finish scraping.

YMMV, but a timeworn analogy that explains my concept of cutting vs scraping: Carving roast beef on a board with a carving knife blade held relatively parallel to the roast is cutting --- cleaning up the grease and scraps off the board with the blade relatively perpendicular is scraping. In neither is the bevel really riding; it wouldn't cut. The same tool was used, but with different presentations. The former produces large thick slices of meat, the latter wisps of garbage, but I think the scraped board is left smoother than the cut roast.

I had these misguided thoughts while learning to spot scrape an old lathe bed somebody (not me ,G,) had used as an anvil. I scraped very thin layers off the high spots. The spots were revealed by very gently rubbing the bed with a piece of plate glass covered with a very thin coat of bluing . Finally after repeated rubbing & careful scraping the high spots were spread all over the bed resulting in smoother flatter ways. Mercifully, I'll spare you the details of my poor attempts at 'frosting' the ways. :)

Is that a little like what is or should be done with a woodturner's scraper? I mean after cutting with a gouge or skew and before sanding and buffing should we _very gently_ scrape off the high spots?

Scrapers look thick, flat and simple and we think they cost too much for what they are, but actually they are fine turning tools, more like a reamer than an axe. They are for paring off fine wisps or powder, not thick shavings. We shouldn't make do with files, glass shards or whatever is at hand for our scrapers. We don't dis our gouges like that.

For the sake of newbies I'm casting (not trolling) for your thoughts about scraping and I'm asking if there's a need to scrape after even the best cut in order to get the smoothest surface possible. Thanks for reading this far. Hope you figure out what I'm trying to say. Not everyone can agree nor should they. :)

Turn to Safety, Arch Fortiter

formatting link

Reply to
Arch
Loading thread data ...

Arch

I pretty much agree with you. looking at it from the viewpoint of a bowl and vessel maker. A finishing scrape, usually done in the shear scraping mode as taught to me by Del Stubbs is generally my last step prior to sanding. When making a long grain hollow thing-say a vase from branch wood, I may use a skew in the planing mode. This gives a nice surface, but I sometimes get some burnishing (perhaps from bad technique!). It seems to me that Ihave fewer finishing problems when I shear scrape to clean up the burnished areas.

I don't do enough spindle work to male any worthwhile comments on it

Kip Powers Rogers, AR

Reply to
Kip

I considered an opposing view just to stir the pot, but I use scrapers too much myself to make a meaningful contrary position. Joe

Reply to
Joe Fleming

Arch, I think if your scraper is producing mostly dust, you should touch it up on the grinder. In my opinion, a scraper is a cutting tool the uses the very fine edge of the burr for cutting. A properly sharpened scraper will peel off very fine shavings leaving a smooth surface.

When I think about it, I believe that all tools cut. Even sandpaper uses the tiny sharp particles to remove a shaving.

Harry

Reply to
Harry Pye

In Flatland, I was taught that you flatten, use the smooth plane, use the scraper, then finish. Not sand. Not that I religiously follow what I was taught - :o) - but you do get better finish if you Don't sand. Pores don't get clogged.

I'll second Harry on this one. If you are getting powder - flat or round

- you need to sharpen your scraper.

Reply to
Lobby Dosser

Have to add my agreement to all that is being said. I was taught some fine turning techniques by Christian Burchard. He used a freshly sharpened scraper for finish turning and got the wood silky smooth. But as others have said, you have to have a good burr on the scraper and take very, very light cuts and the wood curls off in thread like ribbons.

Flat wood workers know what they are talking about and it's no different with wood that's spinning.

Earl

Reply to
Earl

snip

Finally after repeated rubbing & careful scraping the

Shades of Betty Crocker!

Reply to
Gerald Ross

Your concept of what happens with a cabinet scraper is off. It actually cuts wood using an edge so thin and fragile that it can produce shavings to match. Said edge is secondary to the visible edge, being produced by the burnisher at a greater or lesser angle to the face, depending on desired aggressiveness. Since we have horsepower pulling the wood for us, we don't need or want so fragile an edge, so a lot of people don't burnish a lathe scraper, preferring a edge with a very short bevel, honed to minimize tearing and held so it cuts across, or nearly across the fibers. That said, any edge can scrape, such being described in lathe work as work done with the edge more than 45 degrees from perpendicular to the fibers. You can demonstrate what happens when the force is more downward than forward with a scraper in flat work to gain an understanding of what scraping at high angles does to wood.

You should also rethink that "no bevel rubbing" while cutting business, as I've mentioned more than once. As soon as the edge is below the former surface, that bevel's rubbing on the newly produced surface as the cut continues. It's riding on the beef, too.

Reply to
George

Interesting. I have a friend who uses a 'whisper' cut with a scraper for his finixh cut. It could be my sharpening, but a whisper cut works better on harder woods (locust, osage) than on softer woods (walnut, soft maple). I still get a better cut with a gouge than I do with a scraper. I do have one scraper that has a quarter round grind that is one of my bottom of the bowl finish tools, that I do a shear cut with. I am now doing most of my heavy removal and shaping with my bigger scrapers. I have found it easier to do than with a gouge (perhaps the mass of the steel), and it seems to be a bit faster, perhaps because I am removing a 1 inch wide shaving rather than a 1/2 inch wide shaving. I do think that the gouge shavings are thicker than the scraper shavings so it may be a tie. On another note, I have thought for a long time that scrapers are misnamed. You can take scraping and shear cuts with any tool out there, it is just a matter of how the tool is presented. robo hippy

Reply to
robo hippy

Sort of off the topic, but I keep seeing sharpening tools to add a "burr" to the scraper edge.. I must of missed wood shop that day, what the heck is a burr (usually something that you DON'T want, right? ), and why would you want one on a scraper? I'm assuming it's on a cutting edge, but not sure..

Mac

formatting link
formatting link

Reply to
mac davis

Yep, It's actually _the_ cutting edge. It's that thin secondary that's fragile because of its form, but capable of taking a shaving you can see through. Or, you can turn a more robust variety for scraping glue. Also vulnerable to heat, because the smaller section doesn't move it as well as a thicker edge. Not as anyone who's used one in flat work would say, of course. They heat up the main piece of metal and burn your thumbs.

formatting link
formatting link
You can see by the diagrams why the scraper is held fairly close to vertical. Some just leave the sharpening burr - that sort of rough edge that you feel, and mostly hone away after you remove a tool from the stone. Very aggressive, but tears things up worse than a finer-toothed edge.

Reply to
George

Having used scrapers a lot for flat work (probably signifigantly more than on the lathe) It's interesting to note that on the lathe, the scraper is flat by nature, but using cabinet scrapers on flat work is best done by bowing them in the center with your thumbs (or scraper holder) to make them more like a shallow gouge. Given that ?most? (at least as far I know) turners leave the grinder burr on after sharpening gouges, it seems that that fresh off the grinder cut is almost always the work of a "scraper", regardess of the tool's profile. (with the possible exception of the skew- I usually hone those.)

Reply to
Prometheus

=====================

Mac, The "burr" they're talking about is purposely added to the edge of the scraper by use of a "burnisher", usually a piece of round tool steel that can roll the leading edge of the tool upward. If done properly, this can give an amazingly agressive cutting edge, or give you those wispy little threads that look like wooden angel hair. It is almost invisible, but you can feel it with your finger (possibly bloody finger if not careful). If you have a Lee Valley catalog, they have a tool for adding the burr to a cabinet scraper. It will give you an idea of the process. HTH

Ken Moon Webberville, TX.

Reply to
Ken Moon

Mac,

You get a burr from the grinder, but the grinder's burr is very uneven and fragile. I usually hone this off, then use a burnisher to press in a good burr. Joe Fleming - San Diego

Reply to
Joe Fleming

Exactly, Ken...\ and I'm pretty sure that the LV catalog or web site is where I saw it..

Mac

formatting link
formatting link

Reply to
mac davis

Joe.. any links or anything to a burnisher like yours? trying to continue my webucation and further my addiction to scrapers.. *g* Mac

formatting link
formatting link

Reply to
mac davis

Think about it, Mac. The cabinet scraper and its burr are RC 52 at the high end. Generally they're in the forties, with lower numbers less brittle.

formatting link
Check the verbage. Your turning tools are generally M2 steel, of RC 62 minimum. That's a bunch more brittle. The burr you turn may not be as smooth as you want, and is going to break easily.
formatting link
Pure speculation, but I'd say the powder types are going to be a bit worse to try and turn a burr on. All of which is probably why the manufacturers of scrapers for hollowing and such recommend an edge only - sharpen with a flat diamond stone on the face. I like the way the TaW steel on my Stewart tools hold an edge, though they're not magnetic when it comes time to retrieve a loose one from inside a hollowing, which happens too often for my taste.

With no burr you "shear scrape."

Reply to
George

Hi Mac Here's a link to the burnisher, for the lathe tool scraper, you can read up and make up your own mind.

formatting link
However

My normal way is to turn on the grinder sharpen the scraper and leave the grinder running, scrape and before I even see a difference in the scraped surface I am back at the grinder and sharpen.

I do have a burnisher for my scrapers, but I'm not impressed with the results, it's maybe me, but I learned to turn,(bowls,boxes,plates, and everything else) with scrapers, they are not the best tools for a lot of turning, but they were all I had in those days, and yes they cut, the edge last only a very short time, depending on the kind of wood and the way you present it to the wood, it can be really nasty and grabby and it can slice just real fine shavings, it is trickier to learn than the skew in my opinion, but on a skewed angle it is much more forgiving than a flat presentation.

It will rip out grain if you give it chance to dig in and crush it if you force a dull scraper, it also can take off the tool ridges like a razor blade taking the whiskers off of your face.

Even after more than 48 years I am still very careful when using a scraper, and it is mostly a tool for cleaning up a sharp corner blending an interrupted cut, and anything like the inside of and the flat bottom of boxes or similar. It is a very versatile tool, even if not the best for a lot of turning, but I would be up the creek so to speak if I was without.

formatting link
Have fun and take care Leo Van Der Loo

Reply to
l.vanderloo

Thanks, Leo... that's exactly the one that started me wondering...

I've only realized in the last year that scrapers are for more than rounding or squaring the bottom of a box...

It seems that when I just can't quite get the bowl gouge to make the shape I want, the scrapers do it well..

At this point, I think the "burr" is beyond my skill level, but I'll definitely store the info.. (and save the $33.50)

Mac

formatting link
formatting link

Reply to
mac davis

Hi Mac, The less skilled often make the biggest burrs, but we all know that burrs are not beyond your skill level. FWIW for others, a junked engine valve's stem makes a good burnisher. This rubbed firmly, but only once across a scraper's edge or by holding a scraper upside down against the grinding wheel can make useful burrs.

Turn to Safety, Arch Fortiter

formatting link

Reply to
Arch

InspirePoint website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.