Documentation
Episode 1 - Brainstorming
Okay I am slightly behind on this project so I am going to start by making the spiral plan There are a few things that I have to design in parallel.
Rough Design
I had my midterm review with my TA and it seems that I might not finish the whole idea of the Project on time so I am doing a simplification. For one making it all fit into something that resembles the size of the purse may be a littleeee too hard to do with the time limit that I have so I am basically simplifying it into an assembly that has the general shape of honey lemon's purse and has a container that drops onto another platform that then has paint mixed in it and delivered out. Before my meeting today with my TA I have to come up with a rough schematic sketch and a timeline. Woo I have two hours and a class that lasts an hour and a half before that so lets get cracking.
Subsystem Breakdown and Timeline
Subsystem 1 - the bigger conveyour belt that is the "strap" of the purse.
The idea
of this subsystem is that it has three circles that drive the belt around maybe connected together with pulleys
and belts. Each container will have a magnet that allows for it to connect to the conveyor belt. the container
will then hit a limit switch which will let the system know to turn off the electromagnet and it will fall down
a chute into the second subsystem
Subsystem 2 - the linear conveyour belt.
This is from the moment the container falls into it. There will be
some sort of touch sensor allowing the system to sense that the container has landed which puts into
play the rest of the machine and will start the conveyour belt. The conveyour belt will turn until it blocks
the phototransistor with the container and then it will stop and transition into subsystem 3. After it
finishes with subsystem 3 it will proceed to move again and drop the container down another chute
Subsystem 3 - carousel
The carousel has four main components including three drippers with colors red,green,blue, and a mixer.
The carousel will have five servos 1 per dripper and then one for a linear motion for the mixer and another
one for the rotational motion of the mixer. Then the entire carousel will be powered by a motor.
Subsystem 4 - Coding
I will have presets for different colors to be made and this involved a lot of testing to figure out the
right combination and amounts of colors.
So i have A LOT of work to do and this will be the breakdown of the timeline.
Week Nov 17-23: This week I will get the overall CAD done and also start on creating subsystem one. I will
also start the coding to make the system work
Week Nov 24-30: I will wrap up subsystem 1 and start working on susbsytem 2
Week Dec 1-7: I will wrap up subsystem 2 and start on subsystem 3 and integrate 1 and 2
Week Dec 8-14 Wrap up subsystem 4 and integrate 1,2, and 3
Week Dec 15-16: Final tweaking and integrating system 4
DECEMBER 17th - FINAL PRESENTATION
Subystem 1 - CAD
I am a huge huge fan of Onshape so that is what I am going to use and start off with a variable studio.
Some of the things I know I am going to use are bearings so I am going to make sure to have variables so
that I don't have to keep changing dimensions. Apart from that some of the bigger dimensions should also
be able to change without affecting everything.
It is always a lot easier for me to start to design something by sketching it 2d with angles rather than jumping
straight into the CAD. So here are some sketches about how this is going to go down
The way it breaks down is three rollers that work with a plastic as the conveyour belt. Right now
I am trying to figure out how to make sure the whole system stands up. The rollers need to somehow attach
to two plexiglass plates while still being able to smoothly turn. Only one of the rollers is connected to
a pulley and that in turn is connected to a motor but then the follow up question is how to connect those
to the plexiglass as well and then overall connect it to the other subassemblies.
I started the CAD and decided I wanted a master sketch in this subassembly that everything else builds off of
and it is so so gorgeous and clean with the variable studio as well.
The only thing is the way I had imagined
connection the roller to the acrylic was by making it fit into a bearing that would fit into the plexiglass
and then I realized if I did that I wouldn't have a way to attaching the pulley to one of the rollers and the
motor as well. So I have to figure out a way to create enough spacing to put the pulley and motor.
I figured it out:
I can just do what i am doing and slice in a pulley into the middle. One thing about the pulley is that
it is an STL I didn't design so it is a little but harder to work with on Onshape but I can just export it
all together and it becomes one object. I also need to design if the case is going to be entirely covering all the subsystems
or if there needs to be some form of separation. Also I am kind of concerned that the bearings will just pop outbut i
can design something that screws onto the acrylic and holds the bearing in place because only the inside needs to rotate.
One of the reasons I love parametric design is because sometime you just mess up with the size and it makes your
life so much easier. For example my bearing holders... are the wrong size
but i can fix them super fast
All done!!
Subsystem 2 - CAD
The subsystem 2 is extremely similar to the first one except that it is not triangular. This means the base is already made so I only have to remake the band and also maybe mess with the distance and the overall positioning. I am a bit worried that I will be using too much acrylic and i dont know if that is something I am tying to fix or if I am just going to try to find more acrylic. I am trying to design the acrylic in a way thatit decides where everything goes instead of vice versa and so far it looks kind of nice. It is actualy coming together really nicely. I think I can fit the motors inside so that theyre snug and don't poke our making it look more clean and together. I am admittedly concerned about how this assembly is going to go... I made steadying braces so it doesn't fall over apart from that I need to make holes to be able to screw everything together. AHHH this is so exciting!! I just realized if the motor is inside then the pulley is outside. Which doesn't work with my current design but it is not a big deal that the motor is on the outside. I was even able to find the CAD for the motor and I am sure I can find CAD for m3 screws as well. this is going to be GORGEOUS. I am finishing up the last acrylic and I love edit in context because I am trying to keep the consistency and It allows me to see how it would actually look. I finally finished up subsystem 1 and subsytem 2 and now I am going to move on to three but I haven't though much about how I am actually going to operate this one. I changed the CAD to make it shorter allowing the radius to be bigger so hopefully the container can pass more smoothly
Subsystem 3 - CAD
I had a few ideas on how I was going to drip the paint at a correct speed and the initial idea I had was something that had a servo attached at the bottom and it would open and paint would fall out. After doing some more research I found a teapot that has a small marble and a magnet which moves the marble to the side allowing tea to flow out. I really like the idea because that involves simplifying the mechanism allowing for less fail points. The only way is I dont know where I would mount the electromagnet so that it is always in the same place meaning it can't be on the carousel but I don't know if that would make it too far from the marble for it to do anything. I am also making the carousel in the shape of a heart to parallel the screen on honey lemon's bag. I keept making adjustments that break things which I really should've thought out before by making small subassemblies that would adjust themselves correctly to any changes. I also have no sense of size so I am making these paint containers without actually knowing how much paint I would need or how big they should be. I fixed all the assemblies so they are now subassemblies and it won't all simultaneously break on me with me having no idea what is actually wrong with it. I've been thinking about how I am going to deal with the dripping paint since I don't want to buy 100 marbles for $10 so I broke open a ball bearing to steal the smaller metal balls but it didn't work because they are too small so I am thinking about putting some sort of nut or something metal inside a 3d printed ball in an attempt to make it act metallic. Okay so update apparently I can put some magnets inside and create a sphere similar to the paint ball one and just glue it shut. I am super excited about this!! Okay so I set it to print and I should be able to see the results in about 10 minutes. Okay so update it didn't print very well because I did not account for tolerance so the magnet did not actually fit inside. I printed it again and it was a bit bigger but it broke off at the bottom. Apart from the electromagnet I think I am almost done with Sub 3 I may just be missing how to attach the paint containers to the heart carousel. I think I might make two hearts and use shaft collars to keep them in place? Or I can 3D print a shaft that maybe might be thick enough for an m3 to be tapped into it with a washer to keep it flat. Fun update apparently my paint containers run directly into the shaft that spins the carousel. soooo i messed up. I am not entirely sure how to fix this. I think I might leave it because since it is technically due to weight it might just hit the shaft and deal with it itself as long as it does not spill paint
Electromagnet Sidequests
So I am trying to find an electromagnet for my subsystem 3 (the carousel) and I emaile anthony and he said I could use a solenoid but caveat I have absolutely no idea how to do that so I guess we're about to find out wooo. I am back and it seems to bre relatively straight forward if you give a solenoid current it turns into an electromagnet so I should be able to connect it to a digital pin and give it high and low signals which would turn it on and off. Let's find out. I am not sure how i can prototype this but I think I can get an arduino nano and stick some wires into a breadboard because prototyping with esp32c3 is very hard on a breadboard because the connections aren't the best. my breadboarding is working with the bare minimum so I have no idea if this is actually going to work apparently there is not enough current without adding more to it. I think I might have to head to OH or EECS today to figure this out. (Follow up in the electronis section)
Pulleys and Belts
One other thing I am worried about is that I need a specific pulley but I think that the pack I bought are all different lengths and so I don't know if i am going to need to calculate so that it works or somehow scrounge up two more belts. So I decided to make a table knowing that my smaller pulley, an 8mm motor pinion, is .315in and my bigger pulley is 3.2 inches with the belts I have only the 280mm,300mm, and 400mm lengths work giving me center distances of 2.298,2.771, and 4.903in. Which I think may actually be really convenient
Some Test Prints
I sent three things to print: the roller with a pulley, the roller without a pully, and the paint container. THE FIRST PRINT CAME OUT. well the first first one just turned into spaghetti but this one came out super clean. I need to make sure the belts are the right scale but it looks gorgeous. My next set of prints is going to be my bearing holders and one more roller so I can hopefully assemble the first system and maybe a container with a bigger tolerance for the magnet.
prototyping
I am thinking about prototyping today using cardboard to see if all my dimensions will work and then maybe doing some small tolerance test cuts on acrylic to make sure I don't waste my special acryilc. I was actually able to cut out in the EE lab of my dorm and to all the tests. After this I am going to go to metropolis and actually cut it. I was actually super lucky with this because it didn't work with my computer because the laser cutter connects with ethernet and apparently macbooks don't really have ethernet. There was someone in metropolis that was able to help me cut it and I started assembling it but I ran into some issues, for one the bearing holders fit in the first two but not the third acrylic, the motor pinion that I bought was 8mm instead of 5mm and that was mostly all the problems. Everything honestly fit together really nicely. I am a bit concerned because the shaft collar didn't really fit that well on the shaft put I did not maufacture or produce that so I don't know how to fix it and unless it's a metal I can drill I am not sure I can fix it at all. I was able to cut out the rest of the acrylic so I can now mildly assemble the full prototype apart from the belt shaft stuff. This is so exciting. The heart seems a little bit small and I am worried about what is going to happen when I put it all together. Apart from that I am a bit worried about how close the holes to the nearing moutns are because I don't really need it to be that close and it is almost cracking. Apart from that I forgot about holes for screws to mount the smaller bearings but heyyyy it is fine ig?
Electronics
So the first subsystem will need battery power, stepper motor, esp32c3, and a motor driver, and a limit switch. The second subsystem needs battery power, stepper motor, esp32c3, a motor driver, phototransistor. The third subsystem needs battery power,stepper motor, esp32c3,a motor driver, and an electromagnet. In my week3 project I worked an a4988 stepper motor driver but I am supposed to be using a DRV8428PWPR motor driver so I hope some of the pins are the same I was able to find the TI datasheet that told me what all the pins were and I am going to go to OH later and see if they can verify my schematic. I made all three of them and hopefully everything comes out good yay! Okay so I went to speak to Anthony and woah buddy was I wrong. Just for starters the breaboarding I was doing for my electromagnet... never going to work. There isn't enough current I have to design a PCB that uses a MOSFET in order for it to work. Apart from all that I have to somehow figure out how to wire three stepper motors and the electromagnet into a cable that will then be plugged in somewhere. I am more than a little bit overwhelmed and I haven't even gotten to the coding part yet so I guess I'll keep you updated. Okay so the general idea I have so far is creating three board that all connect to the same esp32c3 and control the three motors and the electromagnet. I am not sure but then I may as well connect the limit switch and phototransistor as well I think. I made a schematic wooooo let's see if it works. I realized that even though it is one schematic it needs to be about four different physical board which means that I need headers to be able to connect everything together. I am a bit confused as to how to power everything but I figured out I can just make headers that connect to each other. I checked it with anthony and the only thing he said was to flip the A po and A neg pin to make it easier to make the schematic but apart from that it was good so I am excited to bring it all together. Apart from that he showed me how to change the footprints of the drivers because they are too close together and the tool would ruin the traces of the driver so instead of having pads of 0.4 they now have pads of 0.25 you have to go update in footprint editor -> properties -> and then change one pad and set that as defualt and update the rest of them