<s id="A18-3.21.01">21 The nut now is manufactured in the following way.</s>
<s id="A18-3.21.02">One takes a hard piece of wood (bc), whose length is twice as great as the nut and whose thickness is equal to it.</s>
<s id="A18-3.21.03">On the one side we make a screw (d, d) on half of the [piece of] wood, according to the description given earlier.</s>
<s id="A18-3.21.04">Let the depth of its threads be as great as that of the threads on the screw that we want to screw into the nut.</s>
<s id="A18-3.21.05">On the other side we remove by turning the amount of the thickness of the screw grooves, so that the [piece of] wood becomes like an evenly thick peg (e, e).</s>
<s id="A18-3.21.06">Then we draw the diameter of the base of the [piece of] wood and divide it into three equal parts.</s>
<s id="A18-3.21.07">In one of the two dividing points we erect a perpendicular on the diameter.</s>
<s id="A18-3.21.08">Then we draw from the end (points) of this line that is perpendicular to the diameter, on the entire length of the peg, two straight lines (ty, uz).</s>
<s id="A18-3.21.09">We achieve this by putting the peg on a straight board and furrowing it with pliers, until we reach the thread.</s>
<s id="A18-3.21.10">Then we carefully use a fine saw and saw it through to the thread.</s>
<s id="A18-3.21.11">Then we detach the marked third (utzy) from the peg and carve into the center of the two remaining parts a canal-like groove (fghi) on the entire length, half as deep as the remaining thickness.</s>
<s id="A18-3.21.12">Then we take an iron rod (lknm) and turn it according to the screw threads.</s>
<s id="A18-3.21.13">Hereupon we attach it to the peg (ee), in which is the groove, and let its (blunt) end approach the thread (of wood ending in u), after having firmly connected the two pieces (the sawed off one and the hollowed one), so that one adheres to the other and there remains absolutely no space between them.</s>
<s id="A18-3.21.14">Then we take a small wedge (opqrvw), insert it into the canal-like groove and hit it, until it drives out the iron rod and falls between the two parts.</s>
<s id="A18-3.21.15">Having done this, we insert the screw into a drilled [piece of] wood (<z>, <z>), in which is a completely straight hole measuring the same as the thickness of the screw (dd).</s>
<s id="A18-3.21.16">Then we drill into the walls of this wide hole small holes, placed side by side, insert into them small, oblique plugs (<h>) and let these penetrate so far until they mesh with the thread of the screw.*) </s>
<s id="A18-3.21.17">Then we take the [piece of] wood (T), into which we want to drill the nut thread, drill a hole (<ee>) corresponding to the screw peg (ee) into it and connect this [piece of] wood with the one into which we have inserted the screw, by two posts that we fasten completely.</s>
<s id="A18-3.21.18">Then we insert the peg (<g>), in which is the wedge, into the hole (<ee>), which is in the [piece of] wood (T) that is to be drilled to [form] a nut thread, drill into the upper end (<b>) of the screw holes, into which we insert spokes, and turn it, until it (the peg <g>) penetrates into the wood.</s>
<s id="A18-3.21.19">We do not stop turning it up and down and driving the wedge again and again,**) until the nut thread is drilled as we intended.</s>
<s id="A18-3.21.20">Then we have drilled the nut threads.</s>
<s id="A18-3.21.21">and this is the shape, and with its completion the book is completed (TB) </s>
