X-Git-Url: http://challenge-bot.com/repos/?a=blobdiff_plain;f=curriculum%2Fchallenge-bot.scm;h=1ae84fda5749200cd3f2468639b0c9db87faa513;hb=ca8e4428bad920b3941c1a37d63d823f8046eb12;hp=2284e0e24a4be0b49c809d3ee24b41fe42b1bbc3;hpb=6fc3d47b6cf98c35c63364613bf023f4f882cdd7;p=challenge-bot

diff --git a/curriculum/challenge-bot.scm b/curriculum/challenge-bot.scm
index 2284e0e..1ae84fd 100644
--- a/curriculum/challenge-bot.scm
+++ b/curriculum/challenge-bot.scm
@@ -31,12 +31,21 @@
                   this means the hole needs to be big enough for the
                   screw body to fit through.
                   we want the screw to stay put once it's in place.
-                  the threads of the screw will grip the edges of the
-                  hole it's going through.])
+                  we also want the drill bit to be smaller than the
+                  diameter of the thread.
+                  the screw was chosen so that the hole on the arduino
+                  was bigger than the body and smaller than the thread.
+                  we will choose the biggest drill bit that fits through
+                  the hole on the arduino.])
      (p [here's a diagram of a screw]
         (figure :legend "screw" (image :file "arduino-to-deck/screw.png"))))
     (subsubsection
-     :title [inserting drill bit])
+     :title [inserting drill bit]
+     (p (figure :legend "arduino to deck / insert bit"
+                (image :file "arduino-to-deck/1-insert-bit.png"))
+        [insert the drill bit into the teeth of the drill.
+                insert it far enough that the teeth will clamp on the
+                smooth part of the bit when they are tightened.]))
     (subsubsection
      :title [holding drill])
     (subsubsection