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Shaping & Sharpening Lidded Box Scraper (Read 370 times)
 
Don Stephan
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Shaping & Sharpening Lidded Box Scraper
Jun 6th, 2016 at 1:10pm
 
Like many, I make turned lidded boxes as taught by Richard Raffan.  To finish the inside end and side grain of the base I use a scraper with a radiused tip that flows into the left side of the tool.  The shape of the tip is asymmetric as the radius blends into the straight left side. 

When I first started making boxes I kept the scraper flat on the platform as I ground the tip AND came through the transition to the straight left side.  The left side transition became a straight line angled slightly and wouldn't let me finish scraping under the rim.  I went back to Raffan's book and video and saw that at some point in the transition he began rotating the tool counterclockwise and pushing up the grinding wheel to take off very little metal.  And the lower part of the left side transition was simply honed to renew the edge without making the scraper narrower.

I'm trying to learn where on the curve (at the end of the scraper) to begin rotating and pushing to maintain the most useful box scraper shape.  The curved end scrapes the end grain and transition at the bottom of the base,  the honed side scrapes the side grain under the rim, . . .

Hopefully my question is understandable, the transition on the scraper is difficult for me to grasp and much harder to try to explain.
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robo_hippy
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Eugene, OR, USA
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Re: Shaping & Sharpening Lidded Box Scraper
Reply #1 - Jun 6th, 2016 at 2:05pm
 
I would have to go back and look at that video, been a long time. It sounds like a shear scrape which is what you call the cut if the tool is at an angle to the spin as opposed to a scrape which has the cutting edge at 90 degrees to the spin, or flat on the tool rest with standard scrapers. By rolling it up onto its edge, you can get a rounder shape into a tighter space since it is skewed rather than square to the form. What and how you do it depends on the shape of the box form and bottom. So, if the bottom to wall transition is almost square, pretty hard to do. If the bottom is more open and round, then a properly shaped nose is easier to get through the transition, you just swing right on through. If there is a small radius transition, then when you get to the corner, that would be when you need to get the scraper up on edge. With an 'inside' scraper, which is swept back to the left side, I would want the nose rounded back a tiny bit to the right, like 1/16 to 1/8 inch radius. This makes it easy to go through smaller spaces, and if you roll the tool up on the edge, and handle is level or slightly down, you can't get high sided (high side, farthest away from contact point on tool rest catches, kind of like the skew chisel spiral dig in). With a more round nose, like Doug Thompson's fluteless gouge, you can pretty easily roll it up on edge, and keep cutting with the lower half of the tool. I actually prefer negative rake scrapers for this now as they are 'catch proof', but I can probably figure a way to get them to catch.....

robo hippy
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Don Stephan
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Re: Shaping & Sharpening Lidded Box Scraper
Reply #2 - Jun 6th, 2016 at 6:59pm
 
Sounds like we are using the tool almost identically, although I'm more often flat scraping the end grain in the inside bottom of the base and doing a bit more sanding.  My puzzlement is grinding/honing through the transition on the scraper tool.

Haven't seen most of the cult movies you mentioned, can't imagine you in Rocky Horror Picture Show, another classic cult movie.
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robo_hippy
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Re: Shaping & Sharpening Lidded Box Scraper
Reply #3 - Jun 7th, 2016 at 10:10am
 
Flat scraper cuts seem to tear a little no matter what. I do need to get back into boxes and containers, and want to learn hook tools. Most likely the finer the burr, the less pull you will get when you cut, so from my 600 or 1000 grit wheels, it will be minimal. Shear scrapes are another way to reduce the pull of the cut. The broader surface of the flat scrape makes it a bit easier to smooth out the ripples. I am doing a lot more experimenting with NRS's (negative rake scrapers).

I did watch the Rocky Horror picture and it was okay, but didn't really like it. Loved the Scott Pilgrim and Napoleon Dynamite too....

robo hippy
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