+ the deck.
+ it can translate and rotate freely.
+ with the first screw, the arduino can rotate around one
+ point on the deck and can no longer translate much.])
+ (p [the second screw limits rotation a lot.
+ it also makes translation even more difficult.
+ it might even be too small to be detectable by directly
+ looking at it.])
+ (p [to choose where the second hole and screw should go, we should
+ keep in mind that the goal is to attach the deck to the
+ arduino.
+ this means minimizing rotation and translation.
+ the picture below shows that the second hole should be as
+ far as possible from the first hole, since that minimizes
+ rotation.]
+ (figure :legend "arduino to deck / keep holes far apart"
+ (image :file "arduino-to-deck/keep-holes-far-apart.png"))))
+ (subsubsection
+ :title [drilling and attaching second screw]
+ (p [to drill the second hole, follow the same steps as drilling the
+ first hole.
+ hold the arduino down as before, and drill through the hole
+ furthest away from the first hole.
+ then insert and tighten the screw as before.])))
+ (subsection
+ :title [third and fourth hole and screw]
+ (p [even though the arduino is pretty well attached with just 2
+ screws, we will add a third and fourth.
+ this gives practice drilling and tightening screws.
+ it also keeps the arduino fixed even more rigidly.]))
+ (subsection
+ :title [assessment of arduino deck attachment]
+ (itemize
+ (item [you should now be able to grab the deck and shake it.
+ the arduino should stay firmly in place while you do.])
+ (item [the arduino should be close to but not touching an edge.])
+ (item [there should be no warping on the arduino.
+ this could happen if the screws are too tight.]))))