I guess there can be two different cuts here, one is a shear cut, which implies a bevel rub, and the other is a shear scrape, which is pretty much the same cut but the bevel is not rubbing. This one to me is not a scrape at all, but is called that because the bevel is not rubbing, but I can't think of another name for it. This is a video I need to do, and have some things to ponder before I take it on.
Here is one that is fairly good:
https://www.youtube.com/watch?v=tZ0utpU9Aik
Shear refers to angle. Scraping cut is the scraper flat on the tool rest, and the cutting edge is at 90 degrees to the rotation/spin of the bowl. You can use scrapers, gouges laid over on the side with flutes at 90 degrees, or skew chisels/negative rake scrapers. The idea with the shear angles is like speed bumps in the parking lot. Hit them square on (scraping cut) it can be a sharp bump. Hit them at a 45 degree angle, and the bump gets smoothed out. Hit them at a higher angle and the bump is minimal. With cutting edges, scraping is rather blunt and tends to pull. The higher shear angles are better at gently lifting the shavings off the wood than shaving cuts.
Jimmy Clewes was the one who got me thinking about shear scraping for the finish cut. His comment was some thing like 'if you have a bevel rubbed finish, then when you start sanding, first thing you have to do is cut through the burnishing'. This is why my preferred cut is a shear scrape. My favorite tool on the outside is a swept back scraper. It is easy to drop the handle and get a shear angle in the 70 to 80 degree range. Another benefit to scrapers over gouges for this cut is that with a gouge, you have to roll the flutes over till you can barely see the edge cutting, if you can see it at all. With a scraper, the cutting edge is easily visible. I always do this as a pull cut, and move with my body, which is Thai Chi 101. Now, depending on the wood, the burr can make a lot of difference. On softer and more punky wood, I am really liking my fine CBN wheels, 600 and 1000 grit. Lousy edges for roughing, but excellent for clean up in figured and softer woods. They will clean up things that the 180 grit burr won't. A gouge that has more of an open flute (Doug Thompson's fluteless gouge, or a spindle/detail gouge with a ) nose), and a 600 or 1000 grit grind on it also will really clean things up that the standard more closed flute designs can't do because you can roll them over on their sides for a higher shear angle. You can get close to those angles on the outside of a bowl by dropping the handle, but impossible on the inside of a bowl.
The inside of a bowl is more difficult. Bowl rim, tool rest, and lathe bed can all get in the way. Gouges are totally out as far as I am concerned. You can use a ) nosed scraper, which is my favorite tool here. Drop the handle a bit, and only contact on the lower half of the tool so it doesn't tip over and catch, kind of like when using skew chisels. Again, a pull cut.
Now another advantage of shear scraping is that you can get a piece almost perfectly round. Since you are not rubbing the bevel, you are just taking off the high spots till the piece is round. When rubbing the bevel, you always get a little bounce, part of which is from grain orientation as the cutting edge works differently going with and against the grain. Tool pressure can contribute here as well as a hollowed out bowl being some what elastic, so all of these keep a bevel rubbed finish cut from being perfectly round. Not a problem big enough to notice unless you are trying to go less than 1/8 inch thick.
For tool rests, on bowls I always use a curved rest. One practical reason is that you just don't have to move the banjo and adjust and pivot the tool rest as often. They do make it easier for one continuous cut from base to rim, and from rim to bottom of bowl. The J rests and the 1/4 arc of a circle rests work. I prefer a S shape. The only one out there that I think has perfect shape for inside bowls is a blue cast metal one that Craft Supplies sells. It needs hardened drill rod on it.
I may have been doing hand honing all wrong these last years, but for sure the fine grit CBN wheels took it up a notch or three...
Hmm, I did run on there a bit didn't I???? As I said, getting ready to make a video clip of it...
robo hippy