hey robot fans welcome back to the build last time we got choppers feet motorized
and driving around today we're gonna see if we can get those feet attached to the
body and have the whole droid drive around right off the bat I've updated
the foot from the last video I got some feedback from the Facebook chopper
builders group that I might run into some clearance issues with the bottom of
the foot I decided to drop those wheels down a little bit to give me a full inch
and a half of clearance I also reduced a lot of the bulk of the
frame to make it a little bit easier to print the mechanical guts of the foot
are still identical just the frame has been shifted and reduced a lot of
builders tend to name their foot drive so I decided to name mine the Bluth
stair car if we take a look back at the functionality we discussed in episode 1
I want chopper to be able to switch from two leg mode to three leg mode at first
this decision was strictly for the cool factor and a little bit of Builder cred
but as I was developing the head arms and trying to animate them and working
in the head not animation I realized that those functions will work a lot
better on a fully upright droid also they'll look a lot better on a fully
upright droid so I'll do all of my driving in three leg mode and then stand
them up straight for all the extras keeping this function in mind is really
important while we build the leg this axle here will be fully free spinning so
we need to be able to lock it into place to keep Chopper from toppling over we
also need to be able to keep the foot parallel to the ground as the Droid
transitions from each leg mode if we take a look at the stair car I have a
second axle in place I'm going to connect this to a rigid axle running
through the body using a piece of m8 study we can worry about all the
hardware parts later but for now we just have to keep this channel in mind while
we build the rest of the parts of the leg the length of the leg is going to be
under a lot of stress and since I can't print it all in one piece I want
something solid running through the leg so there isn't as much force being
applied to the joints back in episode 4 I bought some linear slides that I ended
up not using for the head arms I'm going to repurpose those rods as studying
running through the length of the leg to keep everything as sturdy as possible
all the printed pieces will slide onto these rods with the ankle and the
shoulder acting as a cap on each end the channel for the standing rod will run up
through the middle and another channel will run from the tip of the ankle all
the way up through the side to route the wires I purchased some hollow stainless
tubing to use for these little hydraulic rod
shoppers legs so that'll be perfect for housing all the wires while all this is
printing we can start tackling the shoulder side of things continuing right
along with the theme of getting it right the second time I'm going to have to
enlarge the current shoulder cavity from here to here so all of these crossbars
are going to have to go I'm going to take this time to address the number one
frequently asked question I receive when are you going to release the print files
for chopper two which I always reply when I know everything works for sure I
hope this little video of me hacking into my droid supports my case a bit for
holding off on releasing the files after cutting the bulk of the shoulders off I
drove everything nice and flush so I can install our new shoulder this shoulder
gives a little space for a main axle as well as the rigid axle to attach to the
foot and recesses for our rotating connections to the leg the heavy lifting
of the two three two leg transition is going to be done by these two linear
actuators I got them off eBay they are 24 volt actuators with a three inch
stroke they can lift 330 pounds at 10 millimeters per second these will be
positioned inside the body just behind the shoulder and push and pull an arm
which will give us the rotation around that axle this interior arm will attach
to the shoulder using four m12 bolts which will rotate freely through the
holes in the shoulder to print this interior arm I got to employ one of my
favorite printing techniques which is to pause the print at the correct layer
insert the hardware and print overtop to capture that hardware in this case for
m12 nuts into the final printed piece since the end of the arm will be
tracking the circumference of the circle I had to build a piston type mechanism
to allow the linear actuator to push this area as it moves in and out of the
actuators line of travel to add some control to this mechanism I've installed
two end stops on each shoulder these will be triggered by a little dangly
ball attached to the bottom of the arm I can't help but think of butters in the
frig strike episode every time I look at this but having this little chin ball
here allows me to reprint it as needed to really dial in the angle of the
rotation I've built my latest and greatest of temporary control boards
this will be the last temporary one I have
to build I hope it's pretty simple it's just an Arduino controlling to BTS 79 60
motor controllers and receiving feedback from those four end stops I also set up
a little temporary button to trigger the leg transition I'm going to do a couple
quick tests of the end stop code as the legs are getting done on the printer the
code is pretty simple when I push the button it drives the motor until it hits
an end stop that end stop cuts the motor and changes a variable value from true
to false that value determines the direction of the motor on the next
button push now that the legs are done printing I can assemble them while
routing the wire and the eight millimeter standing rod the wire will
have a detached point here at the foot but that's going to be a little bit
tricky to get to once the foot shell is on so the main detached point will be
inside of the shoulder bill this connection will allow me to take the
legs off as needed for both maintenance or if I have to take them off to travel
somewhere this connection will eventually be bullet connectors like in
the foot but I can't do that until after my final post paint assembly so for now
I'm gonna use these walnuts from there the wires get routed through the axle
and into the main cavity via some holes I drilled with my new super-badass
Teenage Mutant Ninja Turtle looking drill bits this is the final hardware
configuration for the standing bolt it's a piece of m8 setting attached to two
different types of loops at each end using some coupler nuts one is an m6 I
loop with an m8 shaft coming out and the other is custom printed I cut all this
down to size and left a little room in my couplers for tightening later on the
leg has a large bearing in the back similar to the one in the shoulder and
this will press up against the bushing to keep it properly spaced against the
body an m12 steadily placed through the length of the body which will act as our
standing bolt anchor as well as be an anchor for the top of the third leg
assembly when we get there with all that installed we can do our first transition
from two legs to three legs obviously we don't have a third leg yet so I'm just
going to have to hold the droid up but we'll be able to see the legs move into
their proper angles okay here we are three leg position not sure quite what
the angle will be with that foot down but probably somewhere in here then when
we push the button again
it returns to two leg position which is great
you
we can also take chopper for his first two-legged spin he's still running
smoothly on some very conservative 12-volt throttle I'm very confident that
this droid will run as fast as I wanted to with all the additional weight that's
gonna be added I think that is gonna do it for this video the next big step to
take here is going to be adding in that third leg but I think before I do that I
may do a quick video on the front utility arm
I want to block out that space before I start designing the third leg so stay
tuned for that if you like these videos please consider subscribing we have to
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a video from my clone build series alright I'll see you next time