Al Navas
11-26-2008, 8:03 AM
This continues my Woodworking in America series. In this new video episode Christopher Schwarz starts the actual process of sharpening a card scraper.
From my blog:
================
Background:
By the end of Part 1, Christopher Schwarz had covered the history of scrapers, using information from “…12 dead guys and 2 living…”, the literature back to the mid-1800s; he was unable to locate earlier references in the literature. He also covered interesting facts about how wood fails, documented with superb photographs of the types of shavings formed. As Part 1 ended, he was filing one edge of the card scraper on the bench.
It is worth repeating here that this work first was published on the PW blog (http://sawmillcreek.org/url=http://www.popularwoodworking.com/article/A_Better_Way_to_Sharpen_Scrapers) on April 20, 2007; you might want to keep the printed article for future reference. In my opinion, though, it is worth the time to watch Christopher Schwarz go through the entire procedure, in which he fully documents every step, and many misconceptions, about sharpening card scrapers.
Now, Part 2:
In this episode Chris does the prep required to get the edge ready to turn the burr, and covers the following:
1. Finishes filing the edge of the scraper, as indicated by complete removal of the marker ink he used for this purpose.
2. Stoning the edge: It is essential to keep the scraper at 90° to the stone surface. The best method he found to do this is to use the same block of wood he used to keep the file square to the scraper face. In addition, he moves the block of wood after every stroke.
3. Sharpening stones he uses: Shaptons, 1,000 and 4,000 grit. Chris makes the point that a polished edge is more durable, and keeps the sharp edge better than a non-polished edge; thus, stoning with 4,000 grit.
4. Polish the side, or face, of the card scraper, using the ruler trick developed by David Charlesworth to prop up a plane iron on a stone to sharpen a very small area on the face of the iron. This drastically reduces the time required to flatten (and polish) the face of the scraper.
5. Burnishers: Use a polished burnisher, not a cheap one!
6. Use a little oil to burnish the face of the scraper, using rapid movements across the entire face. Doing this creates a specific sound that resulted in burnishers being called “ticketers” in days past.
7. This Part ends with some discussion on turning the burr: How? Slide the burnisher? At what angle? Use the Veritas variable burnisher - he set his at 7.2°! How much pressure to use? How many strokes with the burnisher?
It was only earlier this year I finally found myself able to properly sharpen a scraper with any kind of repeatability. But, if you are still struggling to get nice, thin shavings, this session is for you!
To be continued in Part 3…
================
http://sandal-woodsblog.com/wp-content/uploads/2008/11/scrapers-part2-screen.png
From my blog:
================
Background:
By the end of Part 1, Christopher Schwarz had covered the history of scrapers, using information from “…12 dead guys and 2 living…”, the literature back to the mid-1800s; he was unable to locate earlier references in the literature. He also covered interesting facts about how wood fails, documented with superb photographs of the types of shavings formed. As Part 1 ended, he was filing one edge of the card scraper on the bench.
It is worth repeating here that this work first was published on the PW blog (http://sawmillcreek.org/url=http://www.popularwoodworking.com/article/A_Better_Way_to_Sharpen_Scrapers) on April 20, 2007; you might want to keep the printed article for future reference. In my opinion, though, it is worth the time to watch Christopher Schwarz go through the entire procedure, in which he fully documents every step, and many misconceptions, about sharpening card scrapers.
Now, Part 2:
In this episode Chris does the prep required to get the edge ready to turn the burr, and covers the following:
1. Finishes filing the edge of the scraper, as indicated by complete removal of the marker ink he used for this purpose.
2. Stoning the edge: It is essential to keep the scraper at 90° to the stone surface. The best method he found to do this is to use the same block of wood he used to keep the file square to the scraper face. In addition, he moves the block of wood after every stroke.
3. Sharpening stones he uses: Shaptons, 1,000 and 4,000 grit. Chris makes the point that a polished edge is more durable, and keeps the sharp edge better than a non-polished edge; thus, stoning with 4,000 grit.
4. Polish the side, or face, of the card scraper, using the ruler trick developed by David Charlesworth to prop up a plane iron on a stone to sharpen a very small area on the face of the iron. This drastically reduces the time required to flatten (and polish) the face of the scraper.
5. Burnishers: Use a polished burnisher, not a cheap one!
6. Use a little oil to burnish the face of the scraper, using rapid movements across the entire face. Doing this creates a specific sound that resulted in burnishers being called “ticketers” in days past.
7. This Part ends with some discussion on turning the burr: How? Slide the burnisher? At what angle? Use the Veritas variable burnisher - he set his at 7.2°! How much pressure to use? How many strokes with the burnisher?
It was only earlier this year I finally found myself able to properly sharpen a scraper with any kind of repeatability. But, if you are still struggling to get nice, thin shavings, this session is for you!
To be continued in Part 3…
================
http://sandal-woodsblog.com/wp-content/uploads/2008/11/scrapers-part2-screen.png