Well to date only 343 people have read John Lucas post on slicing vs scraping and putting the categories of cuts and tools in perspective. This is important stuff. I am thrilled to see it get out there. John, how about an AAW article so everyone can hear the truth. There are options. There are different results. Take whatever path you desire(and the consequences). They all have their plusses and minuses. But that thread clears up the confusion and sheds the light of day on a very complex topic. Not only Johns eloquent dissertation but all who chimed in from differing perspectives show the facts accurately. So often emotions and loyalties can get in the way and cloud the issue.
One of AAW's primary missions is teaching, and IMO the differences in results for various types of cutting and scraping should be at or near the top of the list. ...GG
I am thinking that there are pretty much 3 different cuts. One is a bevel rubbing cut, which does slice. Two is a scraping cut, where the edge is at 90 degrees to the rotation of the wood, generally used in bowls and hollow forms. Three is the shear/sheer scrape, which isn't a scrape at all, but a slicing cut where the bevel does not rub, and the edge is at an angle to the rotation.
Right on!! I think of the sheer scrape as not scraping at all, but slicing with a teent-tinny burr on an angle. The burr acts like a miniature almost microscopic bowl gouge. The angel hair shavings are proof that it is not scraping. It is confused with scraping because there is no bevel support. The next step in getting the best benefits of sheer scraping is to make sure the angle of the sheerness is tilted on an angle that is cutting down hill or supported fibers. Now we get the best results possible from any cutting methods, slicing fibers downhill.
I knock the burr off of every tool I sharpen inside and out, usually with the leather honing wheel of the Tormek with honing compound and followed by stropping on a thick piece of leather also with some honing compound applied. If the gouge flute is too deep to catch with the Tormek shaped leather wheel, I use a very fine curved hone held flat in the flute. For my spindle gouges and skews and bowl gouges (if I have time) I polish the edge and part of the bevel some. This gives me a smoother finish cut, especially in hard, dense wood like cocobolo and dogwood.
I remove the grinder burr on scrapers too, then raise a small burr with a burnishing tool, as we've discussed before.
The sharpest tools in my shop are my carving gouges and carving knives, all of which have mirror polished edges. I understand that these edges don't get the abuse of turning tools but how long can a rolled, smeared burr from a grinding operation stay on a tool with such harsh use? And what's left when that burr is knocked off? - the microscope shows a rough, jagged edge. I don't claim to know what is best, but a edge polished like a scalpel works well for me (when I take the extra time to do it.) It might be my imagination, but it seems like the edge stays sharp longer too.
I was shear scraping today with one such bowl gouge and got wispy shavings maybe 1/16" wide and so thin they floated up in the air around me. Maybe it was the maple.
I have always followed this procedure for my scrapers when I wanted the finest cut. First I polished the top surface just like I would polish and flatten the top surface of a plane blade. I sharpen on the grinder. I remove the burr formed on the grinder with my diamond hone. I roll up a burr using the Lee Valley burr forming tool.
That said most of the time I am not doing finish work with my scrapers and I go straight from the grinder to the wood. If I am trying to get a finely cut surface in the bottom of my boxes I use Hunter tools and forget the scrapers unless I want a square corner.
Mike I get an almost square corner using the #5. I start at the middle of the box doing a bevel rubbing cut. When I get to the corner I rotate the cutter so it's almost flat going from 12 to 6. I'm cutting with the bottom. By rotating the handle out and keeping the cutter flat it moves the cut from about 6 to about 7:30 and I can bump it against the corner cutting it square with just the slightest round. Then I drag the tool up toward the lip of the vessels shear scraping the whole way.
