hey robot fans welcome back this is the second video in my chopper build when we
left off last time I was spinning the lazy susan round and round after a
successful mounting test since then I've gotten a lot of work done I assembled
the rest of the frame I didn't want to make a whole video about the frame
assembly since it's pretty straightforward all these parts are
printed to sit together and then once they're fitted together they're just
solving welded in place using some ABS plastic mixed with acetone there's any
Builders out there unfamiliar with this process please leave a comment in the
description to the video I'll happily do a separate tutorial about solvent
welding I also printed out the skirt it's printed in four pieces I assembled
it and screwed it onto the base using the pre-printed holes there's also a
couple design changes that came up between the first video and now most
importantly in my original design I planned on using these 12 millimeter
bolts inserted into each side of the top ring to support the dome but as I began
planning out some of the motors and electronics I found it would be a lot
easier to install a 12 millimeter piece of Steel studying across the entire span
of the droid this will give the head a lot more stability and ultimately give
me more room to mount things another issue that came up during the frame
assembly was some difficulty getting some of the pieces to grab on to each
other well enough I added a few of these triangular pieces at some of the joints
to give it some extra substrate to the solvent weld too and finally the top
ring has changed quite a bit originally it was going to be a full
ring but as I began playing around with the head rotation and how it was going
to nod and Bob I found using this cutout here gave me more room to let the head
nod and gave me a few extra degrees of rotation that pretty much brings us to
where we are now and you can see I've already made those changes that we just
talked about in the digital file here's the triangles on the frame and I made
the top ring modification I plan on releasing these files soon once I know
everything works for sure and when I do all of these changes and any changes
that come up in the near future will already be incorporated into the file so
there'll be no need to retrofit anything alright with all this out of the way we
could focus on the main purpose of this video which is getting the head
mechanism motorized so let's start with the dome rotation there's two main
thoughts I've had on how to do that the first is just a wheel inside of a wheel
with it driving along the interior rim of the lazy susan
and the second idea is pretty similar only instead of a straight-up wheel it
uses a gear and a toothed track I'm definitely leaning more towards this
idea I'm not sure how well a 3d printed track will hold up over time but I
definitely want to give it an honest go out of the chute I found this website
which generates gears and you can export your drawings as CAD files and import
them right into my 3d program so it worked out perfectly
I made a 12-2 302 attach to the motor and a 96 tooth track to attach to the
lazy susan so eight motor rotations will make one full-dome rotation that will
help when deciding what rpms to use I imported the files and extruded them to
be a little bit taller than the lazy susan you can see here in this section
this is how it's going to look throughout the entire part so having a
little extra height will help me spread the load off of each tooth a little bit
I plan on printing the 12 to 3 lat of semi flex if you've ever printed with
semi flex before you know that it's basically solid it'll just have a little
bit of give to it which will hopefully help mitigate any print warpage or
imperfections in the gear itself also the texture is just a little bit softer
than hard plastic so hopefully it'll be a little bit quieter than two pieces of
PLA rubbing up against each other so we'll see how that works
okay here's what those parts look like printed out but before I install them
there's a little bit of a maintenance issue I wanted to address this lazy
susan has never really spun super smoothly as I would like it to it was
always a little grindy and when you combine that with the fact that I
probably got some metal shavings in there when I drilled all of those holes
I thought it was probably a good idea to take it apart and clean it out a little
bit while I was researching how to do that I also found that replacing the
stock metal ball bearings with Derlin acetal resin bearings could really go a
long way so I purchased some of those from mcmaster-carr and I emptied out all
the stock metal ball bearings there was 282 of them total I wiped out the stock
grease that came with the Rings and I applied some white lithium grease in its
place which you can grab on Amazon after that I closed it up with the new Durland
ball bearings inside and I have to say the difference in the rotation was night
and day this was a really inexpensive mod it took me about a half an hour to
do and the results are really fantastic you have any issues with your lazy susan
I would really consider doing this log okay I've mounted the track onto the
lazy susan using some one-and-a-half-inch number ten screws I
also mounted the 12 to 2 it's a Pitman 24 volt motor with a 19 point seven to
one gear ratio and it spins at about 200 rpm the shaft of the Pitman motor is
d-shaped so I recessed the matching cavity into the semi flex gear to fit I
also left a three millimeter channel so I can insert an m3 set screw against the
flat portion of that D shaft that should keep the wheel nice and secure as it
rotates now we have to figure out how to mount these pieces to the frame my main
design is all based off the idea of having a ring mounted to the bottom of
the lazy susan as I began playing around with the design I came up with this
interior ring structure that I really liked I added in the Pitman motor to the
right side of the droid and I wanted to keep the motor as close to the axle as I
could so the weight would affect the balance as little as possible from there
I started refining the design and removing sections I didn't need until I
came up with these two shapes they will both mount to the outer ring and have a
bearing installed to spin along the axle they also each have a step in them to
allow the gear to rotate freely so this is what all that looks like installed
like I mentioned there's a bearing in each one of the mounts which the axle
will slip through the mounts are attached to the outer ring of the lazy
susan using some self-tapping wood screws and then the whole assembly is
threaded through the axle along with two nuts and to lock washers which are used
to set the horizontal position along the axle this is still a very free spinning
assembly so I attached some zip ties at the front to keep it level while
everything was getting installed I also installed the semi flex wheel so now we
can test I have a 12-volt lipo here which we can use just to test the
rotation so there's that I can see right off the bat the semi flex wheel is
pretty wobbly so that's why I'm going to need to be replaced or rethought but for
the most part it looks pretty good it's way quieter than I thought it was going
to be this is only running 12 volts at the moment it is a 24 volt motor so
we'll see what happens when we add in the full power the next step is going to
be adding in a control panel so we can start controlling this thing with the
micro controller I want to use the shadow Padawan system for this which
uses the ps3 nav controllers so I'm going to build out that control panel
and putting some code in the Arduino so
here's the control panel if we go through it starting at the batteries we
have two 12-volt batteries wired in series giving you 24 volts those 24
volts go to a blade fuse that has a 25 amp fuse in it just for a little
protection from there goes to Power Distribution I have a 24 volt rail here
which gets split into two places the first place it goes to is to the voltage
regulator which steps the voltage down to nine volts and that nine volts then
powers they Arduino the other place the 24 volts goes to to this motor
controller this is a BTS 79 60 motor controller and that will send a PWM
signal to the motor to rotate the dome alright we're all set up and ready for
our first test I took the liberty of updating the semi flex wheel
I bought a motor coupling off Amazon and reprinted the part to fit that it has
four screw holes in the bottom and two recesses for em three set screws on
either side of the D shaft this will help ensure that that wheel is really
locked onto the motor and is spinning as true as possible now we're ready to do
our first shadow based code test so if we use the ps3 controller we can move to
the left and to the right so we know the codes doing well it's using PWM so we
could really slowly move it and speed it up stop on a dime also go the other way
and we really have some good speed control here based off of the stick and
how much I'm moving it left to right
we're also now at 24 volts before we were running this at 12 volts so this is
the full speed of the dome okay great I think that works awesome the next step
is going to be getting rid of these zip ties by installing the nod functionality
that will keep this entire assembly level and give us the ability to move it
up and down and give chopper his nod so let's take a look in 3d studio max and
how we're going to do that okay so this little servo installation is what's
going to control our nod the servo is a high tech HS 805 B b-plus servo it's
super beefy and it should be all we need especially with how little travel this
function actually needs it's mounted to the frame using the pre-printed mounting
holes and it sits on a little printed plate the other end of the mechanism is
another one of my ring structures attached to the outside of the lazy
susan connecting the two pieces I have a simple lever type deal in these little
circular recesses will be two bearings so that the ends can rotate freely that
as the servo rotates it pushes the head up and down at this point I'm going to
add in that revives top ring to the frame so we can start testing the
expense of the nod to do that we'll also need the bottom portion of the dome so
I'm going to start printing a test head at least the bottom part for now so we
can see this thing in action I do plan on building a full test head for the
next video so I can figure out all the electronics mounts and start working on
the head arms so this will just be the first piece of that test head if we look
at the rotation from the side in a section view we can see that we get
about three degrees of rotation in each direction before it hits that doesn't
sound like a lot because it isn't but I think that subtle nod will really go a
long way on the final Droid okay all that set up we can test out the
servo controls and we still have the rotation okay I think that's working
pretty good okay I added in the bottom ring of that test heads to see how it
looks with a nod you can see even though it's only three degrees of rotation it's
quite a bit of tilt and as the head gets taller that tilt will be accentuated
more and more you can see in the rotation that the tenth heads a little
bit wonky I probably could have printed it a little bit better but for the
purposes of this test that they gets perfect I took the liberty of printing
the rest of the Ted Ted that's because I'm going to need it for the next video
anyway I figured our added in so we can see what the entire head structure looks
like with a nod in the rotation
there's definitely a lot more wobble in this mechanism that I would like that's
definitely coming from the plate that the Chevelle is mounted to it's only
attached to one crossbar with two screws so I think if I flesh that out a little
bit I can reduce that wobble quite a bit and it'll look a little bit more stable
okay so we have a functional nod and a functional dome rotation I think that's
where we're going to leave it for this video next time I'm going to stick with
the head and try to tackle the head arms so that should be a lot of fun directing
videos please subscribe and also check out the links in the description to my
social media accounts and I'll see you next time
Oh