rsser
25th January 2009, 03:25 PM
A recent American Woodturner mag reported a test of how cleanly various scrapers treatments left end-grain poplar.
The winner was one with a lapped top and a burr or hook turned up with a diamond hone. 2nd place went to one lapped with a hook turned up with a burnisher. A dry ground burr performed poorly.
I had a play with a dry English Ash spindle blank comparing the second two in cleaning up the cylinder which had been trued with a forged spindle gouge. (Which btw left a cleaner finish than a roughing gouge). The scraper was 3/8" thick Record steel 1 1/2" wide, initially square-end but now slightly radiused for this kind of application.
The Ash as you'd know has distinct spring (wide) and summer (narrow) rings.
The summer grain ran somewhat unevenly through the piece, with some forming an elongated oval at the surface, while the rest ran in planes parallel to the spindle axis. The first I'll call unsupported grain and the 2nd supported.
So the result was this: the dry ground burr left a cleaner finish on the supported grain and a worse finish on the spring wood adjacent to unsupported grain compared with the burnished scraper.
It may be that a finer burnished hook would change this result. On this occasion the hook was distinct and produced with 3 swipes on the Veritas turning tool burnisher, and there was some evidence of the 'self-feeding' noted in the instructions with that unit.
I've still to do the planned tests on the durability of edge treatments.
Hope you find this of some slight interest :rolleyes:
The winner was one with a lapped top and a burr or hook turned up with a diamond hone. 2nd place went to one lapped with a hook turned up with a burnisher. A dry ground burr performed poorly.
I had a play with a dry English Ash spindle blank comparing the second two in cleaning up the cylinder which had been trued with a forged spindle gouge. (Which btw left a cleaner finish than a roughing gouge). The scraper was 3/8" thick Record steel 1 1/2" wide, initially square-end but now slightly radiused for this kind of application.
The Ash as you'd know has distinct spring (wide) and summer (narrow) rings.
The summer grain ran somewhat unevenly through the piece, with some forming an elongated oval at the surface, while the rest ran in planes parallel to the spindle axis. The first I'll call unsupported grain and the 2nd supported.
So the result was this: the dry ground burr left a cleaner finish on the supported grain and a worse finish on the spring wood adjacent to unsupported grain compared with the burnished scraper.
It may be that a finer burnished hook would change this result. On this occasion the hook was distinct and produced with 3 swipes on the Veritas turning tool burnisher, and there was some evidence of the 'self-feeding' noted in the instructions with that unit.
I've still to do the planned tests on the durability of edge treatments.
Hope you find this of some slight interest :rolleyes: