C-1.15-8 Nipple Plates, 6-24 pt (1920?)
ATF drawing No. C-1.15-8, "CASTING MACHINE NIPPLE PLATES 6-24 PT." This is a combined operation sheet and engineering drawing. The date of this drawing is not legible; my best guess is "May 2, 1920," but I could easily be wrong. While this drawing's title does not specifically note that it is for the Barth type caster, the information from Theo Rehak accompanying the photocopy of this drawing indicates that it was.
Although it is for 6 to 24 point sizes, it is significant for other sizes because it specifies the alloy used, the heat treatment of the piece, and the characteristics of the grinding wheel to be used on the surface which faces the mold.
In the letter which accompanied the photocopy of this drawing, Theo Rehak indicated that attempts at The Dale Guild to use regular oil hardening tool steel for Barth nipples were unsuccessful (a piece so made "... lasted a whole afternoon (!)", while "the originals never wear out ... well, maybe after 40 yrs or so.") This experience fits the information in this drawing, because the "L-XX" steel specified (with, fortunately, full metallurgical data) is specifically a "high speed" steel. The "L-XX High Speed Brand" was a brand of high speed steels marketed by the Atlas Crucible Company of Dunkirk, NY. ("L-XX" is a brand name for a product line, not a designation of a particular alloy.) The "high speed" steels were developed in the 1890s for what was then high-speed metal cutting on machine tools. Their primary property is so-called "red-hardness" - the ability to retain their hardness at elevated temperatures. This property would make them ideal tool steels for nipple plates.
The "L-XX" brand steel specified is 18 percent tungsten (W), 4 percent chromium (Cr), 1 percent vanadium (V), and 0.70 percent carbon (C), with the remainder iron (Fe). This is the basic composition of "T1" high-speed steel, which was the first patented high speed steel. It is a standard alloy which is still readily available commercially.
Drawing provenance: American Type Founders to Theo Rehak. Photocopy from Theo Rehak to John Hern, 1996-10-15. Hern estate to Schuyler Shipley (Skyline Type Foundry). Skyline to DMM, 2015-01-24. Thanks are due to Theo Rehak, the late John Hern, and Sky Shipley for preserving and passing on this drawing.
The icon above left links to a 2048 pixel wide version of this drawing which has been scaled, rotated and cropped from the original 1200dpi RGB scan. Here is a PDF version of a 600dpi rotated and cropped version of the drawing (11 Megabytes). This is the highest resolution that you probably need to worry about: hern-papers-rehak-1996-10-15-punch-billets-and-atf-barth-nipple-plate-drawing-1200rgb-0003-rot2p0ccw-crop-12928x9264-scale-600dpi-6149x4406-jpg.pdf
Here is a JPEG version of the same (9.8 Megabytes): hern-papers-rehak-1996-10-15-punch-billets-and-atf-barth-nipple-plate-drawing-1200rgb-0003-rot2p0ccw-crop-12928x9264-scale-600dpi-6149x4406.jpg
Here is the original 1200dpi RGB PNG scan (226 Megabytes): hern-papers-rehak-1996-10-15-punch-billets-and-atf-barth-nipple-plate-drawing-1200rgb-0003.png
I am considering the ATF drawings reprinted here to have been published. They are therefore in the public domain as they were published in the US without copyright notice at a time when such notice was required to secure copyright. The digital reprints of them here remain in the public domain.
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