Star Wars Rebels Chopper Build – Part 8- Legs and 2-3-2 Conversion

|0 Comments |11:45 pm

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
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alright I'll see you next time

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