The next day he made a steel bolt
or blank, tapering, and of the size of the screws he thought would be generally needed, leaving the head square, and sufficient length of steel to hold it by in the vice. The next thing to determine was, the pitch or inclination of the thread, and its size. On the edge of a piece of birch bark he set off quarter of an inch, and drew a line from that mark to the edge of the bark, and cut it off, giving the rise or pitch. It was the time of year when boys make whistles. He cut an elder sprout just the size of his bolt, spit on it, and pounded it on his knee with the handle of his knife till the bark came off; this bark he slipped over the bolt, pounded up and boiled some pieces of moose horns, made glue and glued it on solid, put the strip of birch bark around the lower part of the bolt, its straight edge in line with the lower edge, and glued it on.
There was now a perfectly true spiral round the bolt, the quarter of an inch offset determining the inclination, and also the size of the thread. He now filed out a fork from a thin piece of iron just a quarter of an inch in width, the two points, chisel-edged, one sixteenth of an inch in width each, leaving a space of two [Pg 98]sixteenths between them. Commencing at the narrow end of the birch bark, he followed along its edge, cutting the bark sheath as he went, till he came again to the point from which he started, having cut two spirals through to the steel, with a ridge of bark between them two sixteenths of an inch wide. Putting one side of his fork in the furrow already made, he followed round till he came to the head of the bolt. Placing it in the vice with a three-cornered file, he cut out his thread, the ridges of bark on each side forming a guide for a true thread. With file and cold-chisel he cut out segments in the middle of his bolt, the whole length, leaving the thread on the corners unbroken, thus forming a cutting edge at each corner where the thread was broken. He now hardened and tempered it [url=http://shinshu.fm/MHz/20.39/archives/0000532009.html][color=#0F0F0F]It is [/color][/url][url=http://eopold.shiga-saku.net/e1342072.html][color=#0F0F0F]true [/color][/url][url=http://www.saladblog.com.hk/article/235220-warm clothed][color=#0F0F0F]that[/color][/url][url=http://blog.cnyes.com/My/nsisted/article2407202][color=#0F0F0F] when I[/color][/url][url=http://www.napis.sk/ostatne/acquires/][color=#0F0F0F] am t[/color][/url][url=http://blogg.improveme.se/reveale/2017/05/25/bfrozen/][color=#0F0F0F]here where.[/color][/url].
As the next stage of the process, he forged a steel plate,—the ends terminating in handles,—in which he made round holes of various sizes, corresponding to the size of the two ends of his bolt. Into these holes he put this hardened steel screw-tap with plenty of bear's grease, turning it forcibly round with a wrench till the sharp edges at the squares cut a thread on the inside of the hole, and then hardened the plate. With this plate he could cut a screw on the head of a bolt, and with the screw could cut a thread on the inside of a nut. Seizing his broadaxe, he[Pg 99] hewed a great spot on one of the logs of the shop, and wrote on it with chalk,—
"SCREW BOLTS CUT HERE."