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Prototypes and failures Robowaifu Technician 09/18/2019 (Wed) 11:51:30 No.418
Post your prototypes and failures.

I'll start with a failed mechanism, may we build upon each others ideas.
>>14275 Thanks. Looking forward to it. >>14280 The problem with the ball joints is something I should have seen coming, but overlooked it. I'll find another way. I remembered, that my first ideas was to go with some kind of saddle joint anyways. Just went with the idea of ball joints on a whim. There are other options. >What are the threaded rods at the bottom of the torso going to be for? Are they intended to let the whole spine assembly move up and down? They are meant to hold the whole thing in place, till it's pulled in one direction but still restrained by the other stings. Which was a naive idea, I know. Wanted to try it out and thought it was easier to do so than it really was. These rods also represent the twisted string actuators I plan to put into the full scale model. >>14274 Today and yesterday night I worked on some improvements: I gave up on the bad design of the eyes in my test face, and implemented the new approach I mentioned before, based on Bezier splines. It's still not good looking but the underlying technique is way better now, and I can change it more easily. I'm glad I found that way by just trying out something. It only works with creating the Bezier spline in a certain way, otherwise it has more than four points which need to be constrained. Though, the whole idea of the printed face might go nowhere, since printed paper faces of anime characters might look better anyways. Then again, not anyone has a color printer for dead trees or a printshop close by and there might be other benefits. It's slightly 3D for example. The old design was severely flawed, because I made the mistake of picking the wrong layer to build upon. This is something to look out for, happens sometimes to me and can be very annoying. Let's say the eyes and eyebrows weren't really attached to the face in the old design, it only looked like it from the front, but there was a gap in between. That is solved now. For the future I will need to look at some more anime faces to see if and how I can improve the new design. Then I had to add some supports to my shoulder joint design, which I don't even know if it will go anywhere. I have a few other approaches in mind as well. However, the holes for the strings needed some support and I prefer to put such into the CAD design myself. This also proved more tricky than anticipated since it's fairly complex. I printed a sized down model of it and it looks good so far, but the test setup still isn't finished. Then, my elbow joint also made some progress and has been (partially) printed. The photos of my prints are on my tablet, so no photos here but nothing special to see anyways. I hope to focus on the elbow joint and motor holder next, so I can test part of my arm design with the twisted string actuator soon. Also need to cut the tubes and need to make the electronic wire setup less flimsy first, though.
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>>14299 Today was a bit of a dud. Got a clog in my printer. Most likely kind of my fault, I hope, since this is better than a problem with the printer. Fell out of routine during my time without printing, and forgot stuff. I pulled on the filament to get it out, while the nozzle was at 100°C. Should have heated it up to 160-200 first. It broke within the heatpipe, and now I have to disassemble the thing and push it out with a toothpick (again). The upside is, that I'm getting more and more used to this sh...stuff. Like a soldier reassembling his weapon. However, maybe I'll still model something today, so I'll get something done. Days with archievements are just better. The pics are from yesterday. Got my waterbags, for testing my idea with using something alike as a muscle to hold the body bend in some way, without using the motors: Two bags with air, connected in the middle through a valve. Air is on one side through some movement, valve closes, body won't move back to the old state.
>>14312 I had difficulties the last time I tried to design a motor holder mentioned here >>13931 since the holes on the bottom are kind of skewed. I think I found a way of getting around that, by looking at it in a different way. It's important to ignore the openings for cooling, and just focus on the relation of the holes to each other. Also had an idea for the holder of the motor, attached to the arm. I will probably use some slider lanes. I'll put the screws onto the bottom of the motor, sticking out, then it can be hanged into these lanes. Only the heads and some plastic would hold the motor, though. However, I could make the screws longer and plastic thicker, or at some point later make the holder at least partially out of metal. Didn't print any of for now, since I didn't fix my printer yet. But I will, tonight.
>>14327 Is the pic #3 the one with 'slider lanes' Anon? Those look like they will hold another piece that fits into it very securely.
>>14327 These designs are very helpful for visualizing the general support structures inside a robowaifu's shell. Thank you for making these.
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>>14327 My printer works again. I'm really used to disassemble the head by now. It's still stressful, but I won't put it aside for two months again. After printing my elbow design, I found several things to improve, some are already implemented. This includes the issue that I didn't think all things through and I have to do it now. Especially how to exactly holding these part together. No big deal, some more modelling, with try and error. Currently it is way to noisy when moving them around, even without motor. I'll make sure to reduce the friction and let smooth metal run on smooth metal. However, a more general test with a more crude design and the twisted string actuator might come first, since this is what I'm longing for. >>14328 >Is the pic #3 the one with 'slider lanes' Anon? Yes, pic #3 in >>14327, pic #2 should give you the idea. The screws are like a cross, the two screws in the middle need to slide down further.
>>14299 >Thanks. Looking forward to it. Y/W. Here's the little intro project Anon. (>>14353)
>>14349 Several things kept me from maintaining my speed. First of all, I started to think my current approach through a bit more. I wanted to build an arm out of tubes first. However, even a 18 mm tube might be a bit much for the lower arm. I probably should go with something more like picrel 4 from Hamcat_mmq, but with a motor. I also realized that with my current approach the elbow might get too thick, especially since I want to fit in a motor into the elbow later. I realized that if I don't try to get the full tube size from one part of the arm to the other, then I only need something very similar to two shelf holders connected with a pivot. I actually already tried to build something like Hamcat did, though not very good (picrel 5) While thinking about those things, I got back to work at some point and tried to finish the motor holder (picrel 1-3). Well. I had and still have problems, because I don't know how to properly add skewed parts. I need it to be skewed in relation to the arm (picrel 3). Maybe I can do it with two different parts on the bottom, to connect the tube, which I then screw together. Though, the problem also affected my ability to design a hook (picrel 1-3), which I need to test the whole design. I don't even know if that is going to work. I had the idea to make a hook and hang it onto some knob of my drawer, so I can test the motor. Then I also ordered proper connectors for my ESC, since it needs XT-60 connectors and I only have the breadboard connectors to stick into it, which always fall out when the motor moves wildly around. Though, at least so nothing can go to wrong, since it stops automatically. Finally, my printer has problems again. I managed to get brittle PLA, and I think a part is stuck in the extruder. So I might need to disassemble it once again, or twice if the heat break is clogged again.
>>14373 Turned out my printer is fine. It's just that cheap (and a bit old) PLA filament might get brittle if it rests without being rolled up again: https://youtu.be/SvpSxHLotMI - don't have a Boden tube but direct drive, but this is what happened. Gladly, I was able to push out the broken filament without disassembly. I'm currently working a bit on that lower arm, since I looked at it again and think I can do it. Related: >>14397 I could do more, but I'm watching a bit too much YouTube again...
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>>14399 Looks good, but failed for now. I still think this approach to the lower arm is what I want to go with. However, after printing a miniature version I realized that it is harder to do than I hoped for. Ideal would be some simulation with movements, that marks or even subtracts conflicting parts of the design. The white bone needs to be able to role left and right, but in either case it needs to roll over the blue bone. In the best case, these two would touch each other the hole time, so they would support each other. However, since this might not be necessary, that's one ideal that I should better give up. It might have been the reason why it failed. I might be able to do it without such a simulation, but it will take quite some trial and error. So I should focus on other parts for now. I'll try it again at some point. Being able to print a miniature really helps. This whole thing is generally just part of the bigger ideal of her being very human-like. Making humans is hard. So, maybe I should go with something simpler for the start.
>>14474 Oh, I forgot: Picrel one above is something I gave up on already, but I might need to revive later. Cutting out the white bone from the side, using a Bezier spline. I messed up saving the file after I did that, though. Then I thought I don't need it anyways, which kept me going.
>>14474 wow, that looks like a very clever approach. nice one anon.
>>14474 I made progress with my elbow and arm design, but can't test it right now at nighttime. I already connected the motor mount and tested it, including the strength of the twisted string actuator a little bit. I had to change some parts of the "simple" elbow hinge, which took me some time. Also needed to create some mount to attach the whole thing to my drawer, so I can test the arm (picrel 1). I also started to work on a design for a pelvis (picrel 2 and 3). I planed to use a stl file based on a human bone model, slice it, simplify it and make it malleable with parts in parametric design. But now I started a model from the scratch. Don't know if that will work out, but I can do it now and it might be less stressful. It's just important anyways, that the parts which are visible or perceptible to touch through the skin are similar to a human female. Internally I need to use the space differently, since for example the hips should hold two motors with cycloidal drives.
>>14567 > It's just important anyways, that the parts which are visible or perceptible to touch through the skin are similar to a human female. This. Really good insights, Anon. There's little doubt that doing our best to mimic real female body structures will greatly enhance the pleasure and comfort of owning such a robowaifu.
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>>14567 So, technically the first build of the Genera Plattform moved a limb for the first time today. Some minutes ago. I got the elbow moving, also with various provisional arms attached. Of course, I directly ran into several problems, but it still looks very promising. - The motor is not a servo. It can't measure where it is, nor can the arm signal it to the motor where it is, since there are no sensors at all yet. So, the arm goes up, then I have to turn the motor of and the arm goes down. Not a problem. Won't be the only actuator anyways and I realized that it only needs to lift the arm up to 90°, then a weaker but more precise one can take over. I also plan to track the position of the arm of course, and hope the twisted string actuator will be a bit more controllable that way. With no load, I can even not look at it, only give a brief burst and it is up. - Brings us to the other problem, that my holder for the motor isn't very strong, so if the movement goes to far then it takes the whole thing apart and even twists the cables of the motor. - Last but not least, rewinding the strings is a problem. Though, this might be in part because my test controller for the bldc motor doesn't do reverse. Just adding a counter actuator will definitely not work. The strings can twist so hard that it is difficult to unroll them. The arm going down also doesn't mean that it unrolls. Maybe then sting is to flexible and long. Need to learn more about it.
>>14572 Little clarification: The arm might need to go up 90-180° till another (mybe weaker) motor can take over alone. It depends where it starts and if the shoulder moves as well.
>>14572 >So, technically the first build of the Genera Plattform moved a limb for the first time today. Grats! You're making solid progress now, Anon. I also appreciate the improvisational approach for adapting to the environment for you robowaifu R&D lab, whatever the circumstances! :^)
>>14572 Great job but, your motor mount is very thin for an actuator with the kind of power that bldc can give off. The base would also benefit from being able to pivot. You will need to implement a controller that can reverse and an opposing twisted string so the arm can move forward and back as needed. I also recommend using a non backdrivable geartrain to prevent unwanted unwinding.
>>14592 >motor mount is very thin Yes, I'm going to make it stronger. Currently the problem is rather that it is even only sticked together. Not one print nor welded or glued. PLA is very strong, so I'm not worried about the strength of the part, really. >The base would also benefit from being able to pivot. I don't know how you mean that, but I'm going to watch some TWSA videos, which might have similar advice. >need ... controller that can reverse That I already realized. >and an opposing twisted string That you told me before, but I don't know how yet and not sure if I need it (at this point). The arm would fall down due gravity, just by unrolling the string. It even does so, by stopping the motor, but it doesn't unroll completely. >also recommend using a non backdrivable geartrain to prevent unwanted unwinding. Thanks, I'll look into that.
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>>14594 Hi, long time no see I have an idea that aim to resolve the freedom of rotation of joint. It's to use a stainless steel chain and to allow roll axis maybe adding more links will make the roll rotation even better. I am skipping the joint ball prototyping because it's too much difficult to put it in place. Hope I will be able to rework on that project soon, it miss me so much heh. Cheers
>>15293 Hi Evodoll, good to hear from you!
>>15293 Welcome back Evodoll, your idea to use a chain a flexible shaft is pretty clever and I look forward to seeing how it works out. Wishing you the best!
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>>15303 >>15304 Thank you guys, challenges await me !
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Almost done developing a simple easy to print and assemble omni wheel. Most of the ones I found online for printing are not designed to be circular and are harder to assemble. This just requires bar-b-q stiks which are eaily gotten at the Dollar Tree rather then screws. This is the first working protoype with a 4 inch (100 mm) diameter.
>>15686 Brilliant work lad. So question; is this primarily to be a passive 'roller', or do you intend it to be an active 'locomotor' eventually? >This just requires bar-b-q stiks which are eaily gotten at the Dollar Tree rather then screws. I assume some kind of glue or other fastening mechanism is req'd for the stick ends? Or maybe they're tight fit enough? BTW, I greatly applaud your focus on 'cheap & easy' Anon. This is exactly how we'll see robowaifus reach a very broad segment of men everywhere.
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>>15689 Designed to work both passively and actively. >Maybe they're tight fit enough? This is correct, designed to be easily put together by shoving the stick in then cutting the end off. Here's the next result, it works but is a tad big at 2.5 inches thick and 4 inches in diameter though it barely costs anything to make.
>>15695 Curious how the locomotion version is going to, well, locomote Anon? Do you have a clear vision worked out for that yet, prototypes maybe even? I'm really glad to hear the manufacture is both easy and inexpensive Kiwi. Perfect combo! Cheers.
>>15761 By rolling Chobitsu Kun. The friction between wood and PETG/PLA is pretty low. Right now I'm trying to make the mechanism flatter and print faster. PETG/PLA also don't have a high coefficient of friction on most materials. Due to this, I'm looking into materials that will help in the transfer of kinetic energy from wheel to surface. I'm thinking of O-rings at the moment.
>>15765 >By rolling Chobitsu Kun. haha, make sense. I suppose your mention of the O-rings, along with your previous posts about elastic bands as force & rotation drivers pretty much answers my questions. It's going to be great to see unified, modular roller 'feet' available to all our robowaifu kits Kiwi. Drive on! :^)
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Nylon planetary gearset with 78 ring teeth, 32 planetary teeth, and 12 sun for a 7.5 gear reduction ratio. I fucked up the ratio (78-12)/2=33, which is the correct number of planet gear teeth. I also had bad warping on the gear teeth.
>>15890 Looks really cool. But if the nylon is warping why not try printing it in PLA?
>>15890 Looks pretty cool though Anon. Can someone here explain to the uninitiate what a planetary gearset is for? I mean what is the primary purpose/benefit it serves? Can they improve some things?
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>>15894 >What is a planetary gearset (they are also known as epicyclic gearing)? A gear train which relies on three basic element types: sun gear in the center, planet gears which "orbit" the sun gear, and a ring or annular gear which has internal teeth that engage the planet gears. The calculations for gear ratios depend on what element is being driven and which element is used as the output. This website provides a very helpful visual interface for understanding the relationship between the elements: https://www.thecatalystis.com/gears/ This website provides some good general knowledge with helpful explanations on the math involved in calculating gear ratios: https://woodgears.ca/gear/planetary.html >Why use it? Planetary geartrains are legendary in many engineering applications for their high efficiency (generally over 95%) and their ability to create large gear ratios in compact spaces with few gears. A notable advantage they have for 3D printing is the distribution of torque across multiple planets which engage the sun and outer ring. This allows for a higher torque density (the gears can be smaller than other geartrain types for the same torque requirements). Though I would suggest always designing 3D printed gears to be thicker with stronger teeth than is required. They also look cool. (Pic actually related, she is a clock/automata with planetary and many other geartrains)
>>15899 Ahh. So, could the outer, ring-gear be affixed to say, a thigh-strut framework, and the inner, sun-gear be affixed to a drive motor? Sort of as a way to increase the torque for driving the upper leg motions of a robowaifu? Is this a legit way to understand these things or no? >(Pic actually related, she is a clock/automata with planetary and many other geartrains) She's pretty wonderful robowaifu too.
>>15904 >Outer ring as output, driven by the sun gear, with stationary planets. That's definitely an option, would look really cool too. It's really nice to find someone else who appreciates RyuZU, she's been a favorite of mine since the Clockwork Planet anime aired years ago, actually got me into automata and clockwork mechanics. Hidden for off topic
>>15907 Great thanks! That helps me out understanding things quite a bit Anon. >also >inb4 Kiwi is henceforth known simply as the entity 'Y' AnchoR is breddy wonderful too. In fact, scene-related is one of the most touching moments in all animu IMO. Certainly it touches on an incredibly broad swath of topics and interests for us here on /robowaifu/. >
>>15909 Finally starting get the hang of resin printing. It's actually pretty easy, and with way better mechanical accuracy then filament prints. Shout out to RiCODev, his advice saved me a lot of trouble and trial and error. No idea what he was going on about with needing supports, I don't use them and everything is fine. Don't overshake your resin, your prints will have many bubbles like these do. Also, you must be very careful with cleaning the build plate after every print or else your print may end up stuck to the platic on the bottom of the resin vat. The key to successful designs is to shrink the part which touches the build plate to accomodate the first few layers expansion. Also, larger prints should be hollow with holes punched into the shell to releive hydrolic pressure, very grateful to have learned that from RiCODev's warnings. Also, rounding edges to create continuous edges helps, as you can see the overhang is a continuous rounded feature. >Y Very tempting, I've been thinking of changing my name as I do not wish to be associated with KiwiCo and other existing businesses that I'm not affiliated with.
>>15904 You'd usually get your highest gear ratio from having the ring embedded in the robot frame and the output shaft connected to the planetary gears, with an "carrier arm" attached to the bearings.
>>15914 I hate my ender printer and im sure sticking to the bed in the first place would not be as much of an issue with resin printing. What would be a good resin printer to buy?
>>15926 I've only used the Anycubic Photon Mono 4K so, I would have to recommend that. This is a good price for it: https://www.amazon.com/ANYCUBIC-Photon-Resin-Printer-Clear/dp/B09Q93Y374 I too hate my Ender 3, though for bed adhesion resin printers need the metal plate to be cleaned between every print, I use a paper towel to do this. I would also recommend a magnetic plate for the bed like: https://www.amazon.com/Sovol-3D-Upgraded-Platform-Magnetic/dp/B08LYP2VTT/ref=sr_1_2?crid=155V9SBK8WNCS&keywords=photon%2Bmono%2B4k%2Bflex&qid=1650305462&s=industrial&sprefix=photon%2Bmono%2B4k%2Bfle%2Cindustrial%2C184&sr=1-2&th=1 these make print removal much easier. Wishing you luck and success in your printing endevours.
Working on connectors that will work with both resin and filament printers, does anyone know why my resin sometimes creates a large protrusion where a substantial curve meets the build plate? I think it may be my resin, it's Sunlu and seems oddly difficult to work with compared to my friends Anycubic resin. (This failed design can only sustain a few pounds of force before catastrophic failure, oddly always on the left side.)
>>15964 Good shots, Kywy. Nice detail, good focus. May I suggest you add a soft fill light (checkout '3-point lighting') as well? It might give us all a better look at the details on the 'backside'. Just a 'reverse' white placard should be sufficient for a shot lit as in your picrel. No need for a bulb. I'm unable to give you any information on the resin printing issue haven't done any myself yet. However, I want to encourage you again in your goals of inexpensive, easily-mastered construction techniques (and kits eventually?) This will be a tremendous benefit to the unskilled man who wants to create his own robowaifus but doesn't have any clue how to begin at first. >tl;dr Just imagine what the benefits would be to us if we could somehow travel back in time, and deliver our completed designs to our younger selves! :^) Really looking forward to your designs to come Anon. Indeed for all of ours. Onward! >=== -add 'white placard' comment
Edited last time by Chobitsu on 04/22/2022 (Fri) 04:52:13.
>>15926 I would encourage you to look at the larger machines (Elegoo saturn/Anycubic photon x), I know they cost a little more but the extra build area makes the difference between a toy with niche uses and a truly usable machine. Even if you only plan to do small parts, being able to shoot off an entire set at once is a game changer. I was able to make RiCOs arm overnight whereas it would have taken a few days on my old machine. The extra resolution on the small 4K machines only offers a marginal quality improvement. Not worth trading for build volume.
>>15974 Been considering a Elegoo saturn myself as it has a similar build volume to what I already have with traditional 3D printing. Is it really worth getting? Have seen a lot of reviews claiming their units were defective or talking about how it's hit or miss whether resin printing is hazardous material cleaning time or 3D printing fun.
>>14572 Brief update. I'm learning OpenSCAD now. I want to be able to change files with only a few commands.
>>15975 If you need smooth organic features (no layer lines!) then yes. Otherwise, no. See my post in the Rico thread. Yes, the resin is toxic until cured. Read the MSDS for common resins, TL;DR: wear gloves, don't huff it, and you should be OK. Cleaning IS a PITA, you will probably find yourself avoiding resin printing in favor of FDM whenever possible. You will need a dedicated cleaning area.
>>15975 In the 3D printing thread >>94 other smoothing methods have been mentioned. Resin printing might be only worth if you want to print small models which need to be smooth, or for ones which need to be precise and smooth. FDM is the to-go method for a reason. I would rather buy small metal gears from Ali Express instead of printing them out of resin, but for prototyping it might be nice to print some placeholders.
>>15976 Great! Glad to hear from you again, GenerAnon. Good luck with your new efforts, keep going.
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>>15976 Using OpenSCAD for this seems to be quite unexplored, but I had a hunch it would be the right way to go. Some things work quite simple. I wanted to cut out a chest from a cylinder using four half rings, and now I see even quite good results using just one. Other parts are just distorted spheres which are then surrounded by a hull, using the hull() operator. robowaifu-OpenSCAD-tests.tar.gz: https://files.catbox.moe/v8rdf0.gz
>>15993 Neat! Looking forward to your prototype explorations Anon.

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