Radius Scraper Questions

Re: Radius Scraper Questions

Ezekiel Holliday

>Unless you are a professional turner that turns bowls day in and out, the Sorby's are great and a lot cheaper.

Zeke

Re: Radius Scraper Questions

Fred Holder

>I've been using a Robert Sorby Left Hand Bowl Scraper for 10 or 12 years. It does the job very well. This is a 1-1/2" wide by 3/8" thick tool that sells for $89.99 from Woodcraft at this time (Woodcraft Item number is 06092). It is my feeling that the harder ASP tool steel of the Hamlet tools is very useful on gouges and skews; i.e., cutting tools. I would think that the burr on the scraper with these tools would be more brittle and therefore would not last any longer, if as long, as that on the M2 High Speed Steel of the Sorby Scarper.

Re: Radius Scraper Questions

Russ Fairfield

>To add to what Fred has said....

The scraper cuts with the burr that is raised at the cutting edge of the tool.

The M2 HSS such as found in the Sorby and similar scrapers is easier to sharpen into a sharper burr with either a grinder or a burnishing tool than either the 2030 or 2060 steels.

Because the steel is harder, a burr on the edge of a 2030 and 2060 steel is more difficult to form with a grinder, and almost impossible to form with a burnisher. The burr is formed with a burnisher by displacing the metal at the cutting edge, and the harder steels are more difficult to displace.

The choice is between a scraper with a sharper burr that is easy to grind or burnish into shape, or one with a lesser burr that is difficult to form, but lasts longer. I do a lot of turning with a scraper and will always take the sharper edge, even though it requires sharpening more often.

My opinion.

Re: Radius Scraper Questions *LINK*

Mark Kauder, Phenix City, AL

>If you are willing to turn your own handles, you might consider the Serious Tools scrapers. These are not HHS, they are A-2 Carbon steel, but certainly addequate for Scraping. The 1.5" is Scraper is .44" Thick.

I have considered getting one for years, but have not yet.

Mark


Serious Tools

Re: Radius Scraper Questions

Whit Ballantine

>I, too, will opt for sharper over long lasting. It's interesting to note that a carbon steel tool will get a sharper edge than HSS and the HSS tool will get a sharper edge than the powdered tools. Durability is just the other way around. Powdered tools will hold whatever edge they can get longer than HSS which will hold an edge longer than carbon steel. INMHO the trade off between carbon steel and HSS sharpness is relatively small compared to the difference in durability. Therefore, I use mostly HSS scrapers (when I use scrapers at all, which isn't that often). The added cost of the powdered tools plus the difficulty (impossibility?) of getting a really sharp edge rules them out.

Whit

Re: Radius Scraper Questions

Joe Millsap

>I have turned bowl and closed forms for many years and I find the Sorby 200kt combination tool the best. The scraper blade is sharpened at 90 degrees and the burr will cut as clean as anything that I have used.

Re: Radius Scraper Questions *LINK*

Jerry Whitaker

>I have seen Joe do some fantastic work with that Sorby 200kt scraper and can attest to the fact that it responds beautifully to a pair of skilled hands such as his. Joe, I am looking forward to seeing your demo at the SouthWest Association of Turners (SWAT) Symposium on Oct. 1-3, 2004 in Temple, TX. Anyone interested in attending the second largest symposium in the U.S. can visit the website at: www.swaturners.com.


http://www.swaturners.com

Re: Sharpness and Alloys

Lyn J. Mangiameli

>I know statements of this nature are commonly made and repeated, but it is not consistent with my own investigations and I have never found any objective evidence that alloy steels, even exotic alloy steels are unable to be sharpened effectively and comparably. I find such assertions all the more incredulous when they often come from turners who think an edge off a dry grinding wheel of 60-120 grit is "sharp."

I have consistently achieved results that demonstrate that good sharpening technique and equipment can take any commonly available steel to a comparable level of edge refinement, relative to the abrasive particle size of the sharpening medium. I regulary have sharpened and compared plane blades (which are brought to far more refined edges than any turning tool) that have been of materials that have included 02 carbon steel, A2,M2, M4, CPM10 (A-11), and even Japenese laminated carbon steel, and found that edges can be brought to equivalent sharpness. All of these steels can brought to a CONSISTENT scratch pattern brought out to .3 micron using Aluminum Oxide microfine films and diamond slurries and powders. You can go even farther with diamond slurries.

Simply, if any blade edge irrespective of commonly available alloy can be brought down to a .3 micron level of abrasive scratches (and this includes A11 hand plane blades Jerry Glaser provided me), and the geometry is precise, then any turning tool of commercially available steels, regardless of its alloy can be brought to the same level of "sharpness" given an adequate abrasive (i.e., one that is of appropriate particle size and hardness).

It seems to me that this mythology got its start in the early days of carbide tablesaw teeth that were made of cheap carbide formulations that were minimally sharpened. Those conditions are simply not found in modern hand plane and chisel blades, nor in modern turning tools.

If you haven't been achieving the same level of sharpness for your own turning tools, consider investing in a 4x to 8 x hand lens and examine your edges, then adjust your sharpening techniques (which may mean using a finer abrasive or spending more time abrading the edge) to give you the edge you desire. For me, I regularly take all my turning tool edges to at least 1000 grit, and some I take much finer than that, irrespective of alloy. For chisel blades, I always go to at least 6000 and for smoothing plane blades, go out to 12000 (Waterstone) or .3-.5 micron.

Re: Radius Scraper Questions

Peter Teubel

>I have a Sorby 3/8" thick scraper. I also have several Crown 1/2" thick scrapers. The difference is extraordinary. The 1/2" thick scrapers have absolutly NO vibration even at the maximum overhang over the tool rest.

Re: Radius Scraper Questions

Arch

>Lyn, I agree with the argument from your actual experience debunking the myth about getting softer stels sharper. Concerning scraping tools _only, I wonder if a burred edge is easier to put on softer steels and the myth has to do with a burred edge scraping better and merely seeming sharper. But then, my HSS scrapers cut just as well as carbon steel ones. ?? Anyway, so many turning myths--so little time!

All best, Arch

Re: Radius Scraper Questions

Jim Putnam

>Thanks everyone, for your responses. I will drop by a couple of my local woodworking stores and check out the scrapers mentioned. I hadn't thought about the 1/2" ones and the extra strength makes sense to me.

Lyn's suggestion of examining the edge closely seems to be a good idea for learning about the sharpening process, being consistent and effective. I currently use a green 120 grit stone with the Sorby jig, leaving a more refined edge than the coarse stones but with less of a bur. Again, I like an edge that is sharp, more like a plane iron is sharp and this seems to work for chisels.

The bur used on scrapers seems to be a different matter. I suspect that sharpening techniques, varying types of steel and, of course, the type of wood turned. all add up to a fairly wide variety of successful, and unsuccessful methods. Getting control of the sharpening process would seem to be the key to functional sharpening with a scraper.

That being said, which type of scraper should I get? It doesn't make sense that Hamlet would make a $150 scraper that can't be sharpened to cut as well as those of HSS. While I am not a production turner, my grinder has a single wheel and changing the jig from chisels to scrapers is a bother, so a tool that holds it's edge is handy for me. And for those times that I'm turning more CA glue than wood, the tools dull quickly.

I'm not sure that I'm closer to an answer, but I feel better prepared to continue the search. Thanks again for your thoughts and suggestions.

Re: Creating burrs

Lyn J. Mangiameli

>Do keep in mind that there are several methods to raise a burr. I believe Russ has an article on this, but I've never had access to it, so please forgive me if I am being redundant.

Raising a burr on a grinder is probably the most commonly considered, in part because it usually comes automatically as part of the sharpening process. Such a burr is quickly formed, but except in experienced hands, is less controlled that most other methods. Regardless, it is often quite suitable for rough work.

For finer work and greater control, stroking a slip stone upward along the forward bevel of the scaper will allow for burr that can be either fine or course, and located precisely where you want it along the scrapers perimeter.

Finally, and the method I most often use, I scraper burnisher--either hand held or mounted--can allow for a very refined burr (again either large or small in size) that provides a smoother, more consistent and almost always longer wearing burr. For many of the "exotic" steels like is found on the Glaser's, a mounted burnishing peg, such as the Lee Valley turning scraper burnisher, allows the leverage and pressure to form the burr. I get great life of out the burrs I put on the Glaser scrapers.

There is more to be said, but I just wanted to offer a quick reminder that there are alternate methods of forming a burr, and by considering and gaining experience with all of them, you can have a lot more control of the performance of your scrapers.

.....and that's the truth!

TDaniel

>

Re: Creating burrs

Jim Putnam

>While I looked at a variety of scrapers today, I wound up at Boeing surplus buying a piece of tool steel, 1/2 x 1 x 8, that is labled "Latrobe Steel, TATMO COBALT". I thought that by making my own scraper, I'd learn about the sharpening process and, maybe, come out with a usable tool.

Thanks for the additional information about forming a bur.

Re: Radius Scraper Questions

David Linnabary

>The best one I've used was made by King Heiple, it was a 1 1/2" wide Dewalt jack hammer bit fixed in a piece of 3/4" malable steel pipe as a handle that was filled with lead shot. I think he had maybe $25 in it total and probably weighed around 15-20 lbs. The fluffies just rolled off that tool and it was so smooth.

David