:title [challenge-bot]
(chapter
:title [mechanical]
+ (p [let's build your robot!])
(section
:title [arduino to deck]
+ (p [let's attach the arduino to the deck.])
(subsection
:title [required materials]
(p [you will need the things in this picture.
(item [alan wrench])
(item [wood block])
(item [arduino])
- (item [#6-32x3/8\", four of them]))]))
+ (item [#6-32x3/8\", four of them])
+ (item [robot deck, the white thing with a grid of holes1]))]))
(subsection
:title [first hole]
(subsubsection
:title [choosing drill bit]
- (p [choosing the right drill bit depends on what job you are doing.
- right now, we are making holes for screws to hold the
- arduino to the deck.
- 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.
- 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 [the arduino comes with holes in it already, so we will make
+ some choices around those holes.
+ choosing the right drill bit depends on what job you are
+ doing.
+ right now, we are making holes for screws to hold the
+ arduino to the deck.
+ there are two constraints between the hole and screw.
+ each hole needs to be big enough for the screw body to fit
+ through it.
+ the holes also need to be smaller than the screw's thread.
+ since there are holes on the arduino already, the screw was
+ chosen to match it.
+ the screw was chosen so that the hole on the arduino was
+ bigger than the screw body and smaller than its thread.
+ we will choose the biggest drill bit that fits through the
+ hole on the arduino, then use that to drill holes in the
+ deck.])
(p [here's a cross section of a screw in the deck]
(figure :legend "screw cross section"
(image :file
- "arduino-to-deck/screw-cross-section.png"))))
+ "arduino-to-deck/screw-cross-section.png")))
+ (p [check
+ ,(itemize
+ (item
+ [what would happen if the drill bit were larger than the
+ screw thread?])
+ (item
+ [what would happen if the drill bit were smaller than the
+ screw body?]))]))
(subsubsection
:title [inserting drill bit]
(p (figure :legend "arduino to deck / insert bit"
[while holding the drill bit, twist end of the drill to tighten
the teeth.
make sure that the teeth end up gripping the flat part of
- the drill bit.]))
+ the drill bit.])
+ (p [check
+ ,(itemize
+ (item
+ [where should the teeth clamp down on the drill bit?])
+ (item
+ [what would happen if the teeth tightened on the recessed
+ part of the drill bit?]))]))
(subsubsection
:title [holding drill]
(p [hold the drill with one hand on the handle and trigger.
the green circle shows where the hole is.
the blue box encloses the arduino hole and two deck holes.
place the arduino hole mid-way between the two
- deck holes.]))
+ deck holes.])
+ (p [check
+ ,(itemize
+ (item
+ [should the arduino be upside-down?])
+ (item
+ [what should the upper side of the arduino align with?])
+ (item
+ [why not place the arduino up along the left side of the
+ robot?]))]))
(subsubsection
- :title [drilling]))
+ :title [drilling practice]
+ (p [strength check]
+ (itemize
+ (item [put on safety goggles])
+ (item [unplug drill])
+ (item [hold drill in one hand])
+ (item [point drill at the ground])
+ (item [point drill at the wall])))
+ (p [steps for drilling into wood block]
+ (itemize
+ (item [plug in the drill])
+ (item [place the drill bit in position])
+ (item [bring the drill up to full speed, and keep it at full
+ speed while lowering and raising the drill])
+ (item [push down until the drill bit has passed through an inch
+ of the wood block])
+ (item [keep the drill at full speed])
+ (item [stop before the drill smashes into the wood block])
+ (item [keep the drill at full speed by holding the trigger])
+ (item [bring the drill straight back up])
+ (item [hold the trigger down to keep the drill at full speed])
+ (item [once the drill is back out of the hole, let go of the
+ trigger])))
+ (p [check
+ ,(itemize
+ (item
+ [should the drill be at full speed while the drill bit is
+ going down into the wood and coming back up?])
+ (item
+ [how do you keep the drill at full speed?])
+ (item
+ [what would happen if the drill bit were not at full
+ speed?])
+ (item
+ [what would happen if the drill were twisted sideways while
+ the drill bit were in the wood?]))]))
+ (subsubsection
+ :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])
+ (item [push down until the drill bit has passed through the
+ deck])
+ (item [keep the drill at full speed])
+ (item [stop before the drill smashes into the arduino])
+ (item [keep the drill at full speed by holding the trigger])
+ (item [bring the drill straight back up])
+ (item [hold the trigger down to keep the drill at full speed])
+ (item [once the drill is back out of the hole, let go of the
+ trigger]))
+ (p [check
+ ,(itemize
+ (item
+ [should the drill be at full speed while the drill bit is
+ going down into the wood and coming back up?])
+ (item
+ [what would happen if the drill bit were not at full
+ speed?])
+ (item
+ [how do you keep the drill at full speed?]))])))
(subsection
:title [first screw]
(subsubsection
: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.
- smaller numbers means smaller screws.])
+ bigger numbers mean larger screws.
+ smaller numbers means smaller screws.]
+ (figure :legend "arduino to deck / #6-32 screw"
+ (image :file
+ "arduino-to-deck/6-32-screw.png")))
(p [check
,(itemize
(item
[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
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
tighten until the screw head touches the deck.
do not continue tightening after that.])
(p [the arduino should still be flat against the deck still, just
- as it was before tightening the screw.]))
+ as it was before tightening the screw.])
+ (p [check
+ ,(itemize
+ (item [why do we insert the first screw partially before
+ holding up the arduino?])
+ (item [which side of the deck is the top side?]))]))
(subsubsection
- :title [assessment]
- (p [does the arduino stay with the deck when the deck moves?
- can the arduino board still rotate a few degrees?
- warning, if you rotate the arduino board too much, you
- will unscrew it from the deck and you'll have to screw it
- back in.
- rotating a few degrees should be ok.]))
+ :title [assessment of the first screw]
+ (itemize
+ (item [,(bold [warning]), if you rotate the arduino board too
+ much,you will unscrew it from the deck and you'll have to
+ screw it back in.
+ rotating a few degrees should be ok.])
+ (item [does the arduino stay with the deck when the deck moves?])
+ (item [can the arduino board still rotate a few degrees?]))))
+ (subsection
+ :title [second hole and screw]
(subsubsection
:title [arduino board move relative to deck]
(p [without any screws, the arduino board can move independently of
- the deck.])
- (p [with the first screw, the arduino can rotate around one point
- on the deck.])))
- (subsection
- :title [second hole and screw])
+ 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")))))
(subsection
:title [third and fourth hole and screw]))
(section
projects / challenge-bot / blobdiff