This is Part 3 of 3 of the session on Scrapers: History, Preparation and Use, with Christopher Schwarz. Part3 concludes the series on scrapers.
To get some continuity from Part 2 into Part 3, I included the last 3 minutes from Part 2 as the introduction to this episode. This way you can get back to speed quickly.
In Part 3 Christopher Schwarz actually draws the burr on the scraper. This Part starts with some discussion by The Schwarz on drawing the burr, and continues with the rest of his findings on the study he conducted:
- Best way to get a consistent angle at which to pull the burnisher: Adjust the height of the card scraper in the vise, until you find an angle that gives you the best burr. Use this height setting from now on, and lay down the burnisher on the vise chop (the moving face on the vise). This will give you a constant reference angle as you pull the burnisher.
- Use a lubricant when drawing the burr:
– Use a Japanese hair tonic such as Camellia oil (a Japanese hair tonic)
– Other accounts suggest that the Japanese hair tonic is not the best.
– Rather, one should use oil from behind the ear, or from the nose.
- Make several passes with the burnisher, using light pressure. After each pass, “feel” the burr with your fingers.
- Up until today, Chris had always drawn the burr on the pull stroke. After the first pass, someone from the audience asked whether doing it on the push stroke would also work. In the end, it did, and even The Schwarz learned something during this session!
- What pressure to use? “About 12.4 lbs…” <laughter from the audience…>
- Effect of the shape of the burnisher: A tight radius produces a more aggressive burr, i.e., it cuts more at roughly the same pressure; for harder scrapers, use this tight-radius burnisher. But, for softer scrapers he recommends using a wider-radius burnisher. This is the main reason for differences in the shape of the burnishing rod.
- Always buy and use a highly-polished burnisher. He criticizes some commercial burnishers for not being polished enough, which results in jagged edges on the scraper.
- Chris likes to draw the burr while slowly moving the scraper away from the edge. This makes a lot of sense, as it “…keeps the oil moving…”
- Results: Beautiful shavings!
- A huge crowd gathered around Chris and his workbench immediately after the presentation. I am truly sorry I did not leave the camera running to record this!
Approximately the last half portion of Part 3 consists of a Q&A session. Several very good questions originated from attendees to this session, with (what else?) equally good answers from The Schwarz.
I hope you enjoyed this three-part series on scrapers, and hope you will return for more videos from the following sessions I attended:
- Advanced Dovetailing, with Frank Klausz
- Bevel-up vs. bevel-down planes, with Robin Lee, Thomas Lie-Nielsen, and Christopher Schwarz
- Forgotten Workbenches and Workholding, with Christopher Schwarz
- Furniture Design, with Kevin Drake and John Economaki
- My summary and wrap-up, with scenes from the conference.
Not on video, but rather from my own notes, I will have a post on Modern Tools, Tolerances & Myths, with Robin Lee, Thomas Lie-Nielsen, Konrad Sauer, and John Economaki.
I would love to receive your Comments, and any questions or suggestions regarding the Woodworking in America series of videos, and any other content.