To secure the various parts often used connection, using the so-called lock nuts. However, you can do without it. For this it is necessary to saw through the nut, as shown, and tightening it slightly to hit with a hammer.
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Just note - it's not my idea, I offer only the version of her performance. Came across this idea in some military magazine. The conversation was about the Mat-foam: "...However, such...
CHUCK — NO KEY
A nail and a screwdriver located as shown, will help you out, if in the bustle of work had disappeared the key from the Chuck of the drill and the drill bit must be urgently replaced.
