Reg Sherwin Shear Scraper

"Rod" skrev i melding news:oU2Kd.136735$ snipped-for-privacy@news-server.bigpond.net.au...

Why not try a sharp gouge, and _cutting_?

Bjarte

Any edge can scrape, presented either broadly in the traditional definition, or narrowly. The various tools named scrapers only remove one unknown from the equation by providing a stable orientation for the edge.

You say soft, which can mean merely soft, like willow, poplars and others, or it can mean coniferous. Neither respond particularly well to the scraper, as its action depends a lot on the support from the surrounding fibers to keep from pulling rather than severing, with conifers adding the problem of differential softness, where the denser late growth breaks and collapses into the softer early.

Try the edges you have first, making sure to get the toolrest as close to the work as possible, and at a height which will put the part actually scraping almost at centerline. You're looking to get an edge almost 90 degrees to the work and 45 or less to the rotation. DON'T push on the tool beyond gaining contact. Let the wood come to it. If the wood responds to an angle maintained by the scraper under consideration, you might want to purchase it.

I find shear cutting preferable to scraping, but if it has failed you, perhaps you can salvage the piece with scrapers or sandpaper.

Shear scrapers are okay, and I have had decent results with Sorby's, but you can save yourself a lot of work with razor edges and, if that fails, ie. if the wood is just __too__ soft, you can try stiffening the fuzz with either paste wax, or cellulose sanding sealer cut 50% with turpentine. After either of them dries, the fibers will be much more prone to cutting, providing you use the sharpest edge you can manage.

Hi Rod

Real soft wood you say ?, well as far as I am concerned if you can not cut it you certainly can not scrape it, don't matter who's name is in front of "scraper. However there might be ways to improve the ability of cutting or scraping the wood, you could use sanding sealer, CA, thinned white glue, shellac, etc. to stiffen up the wood so you can cut the wood or scrape it, also it does help us if you give more info when asking a question, there is a lot of expertise out there, but they do need basic info to know the what and how.

Have fun and take care Leo Van Der Loo

Rod wrote:

Hi George. My impression is that you're darned near the closest participant we've got to Mike Darlow with his technical view of turning. So, in that light I ask this question:

Would the bevel angle on the underside of a scraper affect the surface quality achieved? The bevel acts as support for the edge as well as establishing the clearance angle behind(under) the edge. In other words, would it make any difference to the surface finish scraping with an edge formed by an 85 degree angle vs. a 60 degree angle?

Remaining in this line of thought, consider a bench plane and the mouth opening for the iron. The front of the mouth supports the wood and helps keep the cut from becoming a tear in the grain and running ahead of the iron's edge. I wonder if some sort of scraper design could be devised such that there's a hood just above the scraper edge that might serve the same purpose. (Something along the lines of the Proforme or other shielded hollowing cutters.)

Edge is an edge. For the type of scraping we do, the bevel is just a sharpening phenomenon. Some scrapers are ground at 90 degrees to the face and still scrape when turned on edge. I'm a clean edge scraper fan, but some leave the wire edge from sharpening on the tool, and old Frank Pain turned his carbon steel with a burnisher. Means their edge is entirely independent of the bevel.

As far as devising a turning plane, I think you need to remember that rotation is changing our stock presentation to us even as we bring the tool to it. Try to figure the optimum type of shaving from one presentation, and it changes with the curve and rotation. For instance, I prefer to shear the outsides of my turnings, producing full twisted shavings , but there is a certain point on the curvature where I take almost no shear, to avoid picking out tiny pieces of side grain. Those who have turned ring porous wood will recognize that effect. For inside you'd need a double curve, (like a gouge?) to have a chance to get a stable shaving, which of course would only be of one type based on exposure, clearance, and bevel angle, and would be entirely unsuitable in some grain orientations.

Though I have used planes on the outside of spindle turnings to good effect, I think the best thing you can do for your surface is to take the thinnest shaving possible. Won't be perfectly suited to all circumstances, but it'll give the best overall results. If you're forced to scrape, so be it. Also take the thinnest as best compromise.

Here's one scraper I use all the time

to scrape the button at the bottom, and the last of a tenon, when I use one. Also the bowls of spoons.

Scraping soft wood is always a problem. The angle of the blade to the wood causes tearing out of grain. If you increase the angle the tool will often become un-manageable. The guarded hook tool system (look at it on our site) gives the user a slicing cut but with the advantage of a limited amount of cutter exposed to the wood. Scraping is fine for hard wood although the short high speed chips comming off the cutter can be annoying and a face shield is helpful Ken Port

Hi Lyn, "....modest price far exceeds its utility" ....typo or damning with faint praise? :) After your's & George's posts, I bet there will be a run on them at L.V.

I know you both sigh and await another of my 'not quite as good thrifts'. :) For the generosity deprived. I find sharpened small engine valves make good scrapers for getting into far away places. Their hardened stems also make good burnishers, but if anyone grinds the stems, make sure they aren't sodium filled.

Ron, What is different about Reg's scraper? Should I try to make one? :)

Turn to Safety, Arch Fortiter

That is embarrasing, it should have been "far exceeded by its utility."

Got to get back to you on the other stuff.

Lyn

Arch wrote:

Lyn, just COC banter with no intent to embarrass. You long ago earned the right to invert speech on rcw when and if.

Turn to Safety, Arch Fortiter