add overview of tightening first screw in 2 parts

[challenge-bot] / curriculum / challenge-bot.scm

diff --git a/curriculum/challenge-bot.scm b/curriculum/challenge-bot.scm
index e9c4d916cfa5e9a824464a865789eacf88a00acb..a51f5472401c4ec12f8aeb7dd62b81cbc9dff596 100644 (file)
--- a/curriculum/challenge-bot.scm
+++ b/curriculum/challenge-bot.scm
@@ -148,7 +148,7 @@
             [what would happen if the drill were twisted sideways while
                   the drill bit were in the wood?]))]))
     (subsubsection
-     :title [drilling screw hole]
+     :title [drilling the first screw hole]
      (itemize
       (item [place the drill bit in position])
       (item [bring the drill up to full speed, and keep it full speed])
@@ -177,7 +177,7 @@
      :title [fastening arduino to deck using #6-32x3/8\" screw]
      (p [the "#6" part of "#6-32x3/8\"" is how big around the bolt is.
              it is related to wire gauge.
-             bigger numbers mean larger screw.
+             bigger numbers mean larger screws.
              smaller numbers means smaller screws.]
         (figure :legend "arduino to deck / #6-32 screw"
                 (image :file
@@ -188,8 +188,8 @@
             [in the motor assembly, there are #4-40x1.25\" screws.
                 are those fatter, thinner, or the same thickness as the
                 #6-32x3/8\" screws?]))])
-     (p [the "32" part is a measurement of how close the threads are to
-             each other.
+     (p [the "32" part of "#6-32x3/8\"" is a measurement of how close
+             the threads are to each other.
              this is related to the angle of the thread, which is also
              called pitch.
              it is a count of how many times the thread wraps around one
@@ -202,14 +202,24 @@
                       the screw body?])
            (item [what about 2 inches?
                        how many times will the thread wrap around two
-                       inches of the screw body?]))]))
+                       inches of the screw body?])
+           (item [where can a tool exert turning force on
+                        the screw?]))]))
     (subsubsection
      :title [fasten the arduino board to the deck]
-     (p [push the 6-32 screw into the deck from the underside and at the
-              same time, spin the 6-32 screw clockwise while looking
-              down on its head.
-              twist until the bottom of the screw is
-              about to stick out on the top side of the deck.])
+     (p [first we'll put the screw into the deck just enough so the deck
+               holds it in place.
+               then we will hold the arduino up to the screw and finish
+               tightening the screw down.
+               with the screw partially in, we do not have hold it as
+               rigidly while we are also holding the arduino and
+               the deck.])
+     (p [push the #6-32 screw into the deck from the underside.
+              the underside is the brown side.
+              at the same time, spin the 6-32 screw so it rotates
+              clockwise while looking down on its head.
+              twist until the tip of the screw is about to stick out on
+              the top side of the deck.])
      (p [hold the arduino board flat to the deck and line up the arduino
               hole so the screw can come up through it.
               continue tightening the screw into the deck, spinning the same