Stone Flat Chisel: the Marble Lettering Tool, Drawn Very Thin (Holford, 1907)

A flat chisel for cutting letters in marble. Frederick Holford's 20th Century Toolsmith (1907) makes marble tools like granite tools, from 7/8-inch octagon steel, but tempers them a little harder, to a very light straw. The lettering tool is drawn out very thin (his Fig. 69); because of that thinness it must be heated with great care, and the last few blows when dressing it are struck on the flat side only, at a very low heat. He gives no edge width, length or carbon content; those are unknown here. Source: F. J. Holford, The 20th Century Toolsmith and Steelworker (1907), p. 130, pp. 122-123 and p. 21 (the hardening bath). Picture: his Fig. 69.

متوسط

An hour

التعليمات

Read Holford

"Lettering tools are drawn out very thin, as Fig. 69, but owing to the thinness be very careful when heating, and make sure when dressing to always strike the last few blows on the flat side only, when at a very low heat."

Draw out the edge

Forge 7/8-inch octagon steel down to a straight edge, drawn out very thin (Fig. 69). Heat with great care because of the thinness. Strike the last few blows on the flat side only, at a very low heat. Straighten the edge with a very coarse file after hammering. Edge width and length are not given (unknown).

المواد لهذه الخطوة:

قضيب مثمّن من فولاذ العدد1 bar

الأدوات المطلوبة:

كور الحدادة

سندان

مطرقة الحداد

كمّاشة الحداد

مبرد معادن

أبعاد غير معروفة

Harden and temper

Heat no farther back than 1/2 inch, taking care not to overheat the thin edge. Dip at least an inch deep into the hardening bath (p. 21: clean water, best a brine with as much salt as it will dissolve, large and cold) so the temper runs back slowly, and stop it at a very light straw, the marble temper.

الأدوات المطلوبة:

كور الحدادة

كمّاشة الحداد

محلول ملحي مشبع

قفّازات مقاومة للحرارة

History and honest limits

Holford sets lettering tools apart from the tooth and plain chisels used to dress marble, which "are not drawn out so thin"; the teeth of tooth chisels are filed in after hammering (his Fig. 70). Edge width, length and the carbon of the steel are not given; an octagonal tool steel bar stands for the 7/8-inch octagon steel.