For fine finish cuts with a scraper, you can do it a couple of ways. The negative rake scraper is one way. It is a very fine burr, and disappears quickly. I do use a small skew, freshly sharpened, with out honing so that it still has the burr on it for adjusting the shoulder on threaded boxes so the grain will line up. With 16 threads per inch, it only takes a whisper cut to adjust, and this tool is well suited for taking off the thinnest of shavings. It is held flat on the tool rest. The n. r. scraper in your picture won't do that as it can't get close enough to the threads and shoulders to make the cut. I think one of the reasons you can use that tool for finish cuts is as much because of the tiny burr as it is because of the bevel angles. Generally, if you use a scraper flat on the tool rest, it will pull more at the wood fibers, and you will get more tear out. It does take a heavier cut.
For bowl roughing, I use a burr straight from the grinder. Hold it pointing slightly down, and plunge in. I started experimenting some years back with scrapers because I knew that they used to be the primary tool for bowls. I wanted to see just how they worked. After working with them for a while, I came to the conclusion that the main cut you use for roughing bowls with a gouge is a scraping cut, with flutes at 90 degrees or so, and some times you lower the handle a bit. What better tool is there for making a scraping cut than a heavy scraper? It does have one added benefit in that most of the shavings are directed up over the top of your hand, rather than across the top of it.
You can also use it for the finish cuts. Have a fresh burr, either from the grinder, or you can burnish one. Hold the scraper at a 45 degree angle on the tool rest (not flat), and make very light passes, taking several passes to remove tool marks. A burnished burr does make a bit finer cut, but some times it depends as much on the wood as it does the tool.
I do tell people to never use the scraper flat on the tool rest for touch up work on the inside of a bowl, especially near the rim. You will get a screeching/howling noise which is caused by the bowl rim starting to vibrate. Especially on larger bowls, this can go to the point where the bowl edges will wobble so much that you get a huge catch and your bowl explodes. Been there, done that, won't do it again. If you have it at a shear (45 degree) angle, and use your hand as a steady rest on the outside of the bowl, it is a much more manageable cut. Much less pressure on the wood, and I have never experienced any catches this way.
robo hippy
:lol: 
