Incredible Folded 3D Printed Mechanisms

i am a huge fan of foldable 3d printed designs but here's the thing 3d printed hinges suck so i've spent the past week prototyping and experimenting with a new approach of foldable 3d printer designs with hinges built in that are actually durable and lightweight it involves some wins a heck of a lot of fails and a dangerous amount of ice lattes let's get started [Music] how's it going guys angus here from makers muse so why do i say 3d printed hinges suck well to explain there's really three ways you can do hinges with 3d print designs the first way is to print the parts separately and assemble afterwards that way you get quite close clearances and you can get quite decent accurate hinges but obviously you need to do the assembly afterwards the second way is quite clever and that's to employ a print in place approach with clearances between each element of the hinge so it prints without fusing and welding together but you take it off the print bed and those those details can pivot and hinge around each other that works pretty well for some applications but it means you have quite large clearances between the parts so the hinges tend to be fairly floppy and loose and the third way is to create a live hinge that is a piece of thin plastic between two details that actually can bend and life hinges are used in all sorts of products and packaging in the real world for example this box from a bluetooth speaker uses a large life hinge in the back there of thin plastic and it creates this really lightweight cheap durable hinge but the issue when you 3d print this sort of thing is that pla for example doesn't make a very durable live hinge and if you want to use a more durable material like a polyamide or a semi-flex 3d printing filament then the rest of your part is going to have those characteristics that's unless you have a very fancy multi-material printer that could print the hinge in a semi-flex and the rest of the print in a more rigid material most of us don't have that so we need to find other alternative methods and i've been doing my research 3d printing on fabric is a really cool technique that dates back quite a few years ago now a lot of the really cool kids in the 3d printing space were doing this sort of thing to create details for cosplay like making chain mail and dragon spikes and that kind of thing and the process is actually quite straightforward you need this nylon mesh material i had a few off cuts in my fabric bin and what you do is you design your print in such a way that it pauses after a few layers then you insert the mesh material into it and then continue the print and because it's got these large gaps the plastic melts in between the mesh and fuses it in place and although the technique gives you these really flexible join components i don't think it's gonna work very well for a live hinge in some sort of mechanical assembly because the fabric itself is a little bit stretchy and it's although is fairly compliant it's also quite fragile and it's not really what i'm going for in designing a print that can fold up together with living hinges good technique to revisit but not really what i'm after so what else can we try well the next logical step was to take some thin plastic like this high impact polystyrene and then insert it into a print mid way as sort of like a hybrid approach to the inserting of the fabric so i tried to design these little posts that i could slip the high impact polystyrene over but it just touched the nozzle and would just instantly move out of place and even if this did work it's only a small contact area where the post star and then you've got to print on top of the hips so it's not going to be as strong as for example the fabric whereas fully bonded but then i thought to myself why am i trying to insert the plastic into a plastic print like the fabric when i could probably just print directly onto the thin plastic and then use that as my live hinge and luckily i have some sheets of 0.6 millimeter pet that i use for my vacuum former and i thought i'd try printing directly onto it with a very simple sort of track pattern that should allow me to make a piece that's rigid in one direction then flexible in the other bit like a caterpillar track but one of the hurdles we have to overcome is the fact this is very thin plastic how do you hold it down to the printed surface and can we heat it because normally i print petg with a heat bed around 80 70 degrees celsius i found very quickly that when i heated the bed up the plastic would deform it would crinkle and warp and go wavy so i tried to hold it down initially with glue stick which i had on hand it's water-based so i can wash it off but i found as i warmed up the bed that even with the glue stick it would warp off it just kind of wanted to bow but anyway not deterred i still tried to print on it and i got this result so getting the nozzle height was a little bit hit and miss and i was way too close so it was for the first half it was way too close and i was dying on the fly but the petg filament did bond really well with the pet sheet and it stuck down reasonably well enough it didn't warp up as much as i expected though it does have a large surface area and the result is pretty good but it's not as flexible as i would have liked uh it's 0.6 millimeters thick so like you do have to really try to get a bend going but once you do it's not too bad it's actually a really durable live hinge which is exactly what i want uh but just a bit too thick so i wanted some thinner plastic but we're in lockdown right now where can i easily get thinner plastic to try out iced coffee cups so i love my iced lattes i'm not much of a fan of hot drinks but i do like cold coffee and i happen to have this iced coffee cup on hand from macas so i thought i'd have a crack at printing on that now it does say it's pet but even after preparing it the same way i prepared the thicker sheet and laying down a what i thought was a really good first layer the parts didn't stick now for this test i was trying to make this sort of offset uh triangle shape that would fold up into a like a sort of like a radar disc or truncated cone kind of thing but it didn't stick and i don't really know why my only theory is that the the cup must be coated with something else because it says it's recycled plastic so they must coat it with something that makes it food safe and i think whatever they coat it with is not allowing the plastic to stick at all which is interesting but then i went to my local coffee shop and i noticed that their cups their ice latte cups were pla which is a good wit like a big win so by this stage i discovered i didn't want to heat the bed at all but the cups uh have like a when i cut the sheet of plastic out of them it's curved it's not dead flat so it does need something good to hold it down and the glue stick wasn't good enough i did find this spray can of spray adhesive which i had since university to you know attach posters to foam board and that sort of thing it's really nasty stuff it's not water-soluble it's like smells horrible only ever use it in an outdoor area spray that onto my print surface basically ruin it in the process and stuck the sheet down i will say it stuck the plastic down like nobody's business it stuck really hard and flat and awesome and i started printing but here's the thing i was lazy and i just turned off the heat bed for the first layer manually and i didn't edit my g-code but you guys will know that you can set different bed temperatures after the first layer so it started heating up again and the plastic came away and the glue failed well you know what the solution to that is so we're onto our last piece of iced coffee play sheet with the plh print on top made sure it didn't heat up at all and this was the result i trimmed the excess away and it actually adhered so good to the pla sheet no no issues at all and it folds together really really nicely it's quite durable and i quite like it now the spray adhesive kind of rubs off it's not water-soluble it's really nasty stuff but this is very viable and i would love to revisit this but i don't have any sheets of super thin pla plastic lying around the best i can get right now is the iced coffee cups but i want to keep testing because i want to see how far i can push this idea into a mechanical linkage and this is the concept i came up with i want to do a ackerman style steering mechanism so it's a really simplified version of one the idea is that there's a joint and as you move one of the joints the wheels on each side will rotate on that parallel linkage thereby making a steering mechanism that can be used in a very lightweight robotics platform like a little tiny remote control car something like that and i designed it using the sheet metal functionality in fusion 360 and then completely bastardizing it because i don't think it's designed to export like nets for sheet metal production but with 3d geometry modeled on top that's the concept but obviously this will only work if the design is accurately cut out afterwards the fabric stuff look you can just sort of trim it with scissors and get around it and you could be a bit more careful than i was but otherwise it's not too bad but with this design it's quite detailed there's holes for example that need to be punched out of the sheet so i thought about using the laser cutter i have this is the flux beambox pro i've had for quite a while and it's a really good laser cutter but in my testing to produce this model i uncovered some of its shortfalls which uh come down to repeatability between each laser run so for this design to work it has to be printed on the pt sheet then transferred to the laser for it to then cut out around the outline accurately and in the past what i've done is i've put a piece of paper down and then laser cut an outline or like reference holes then use those marks as a reference to then run another laser job and cut it out but what i found with the beambox pro is the homing sequence isn't as accurate as it could be so when it went to cut out the outlines it missed by quite a bit like one and a half millimeters or so i still tried to fold up the design it's uh it's stinky because it had some of the glue on it and that but it's really like it's seriously missed especially where the holes are it just doesn't work at all but i still folded it up and it gave me some hope in the mechanism working there is definitely something here it's just needs to be a bit different to this but what if instead of going from the 3d printer to the laser cutter to create our shape we go from the laser cutter to the 3d printer and then assemble the linkage and that's what i ended up settling on to start with i finalized my net in fusion 360 but then i exported into illustrator and this is important because i need to mark where my reference points are that i can use to align my laser cut net on my 3d printer to then print the details onto it so there was a few things i had to figure out with this for example if you just cut out the shape from a sheet it would fall away and then i couldn't reference it so i had to figure out how to do dashed lines in illustrator so it would have like these little tiny tabs holding in place that i could then break away afterwards and this final net had several layers including an outline the the holes for the reference points and then all the different layers including score marks because i found with the 0.6 millimeter plastic i wanted to actually score where the fold lines were and i had to fine tune the laser power and speeds so it wouldn't just blast right through the thin plastic and this is a separate layer as well in my dxf document this is what the net looks like after being laser cut it's got those reference holes as well as the detail of the score marks in there as well but the parts held in place with those tiny little tabs around this outline with that dotted line which means it's held in place well enough to be 3d printed on on the printer now the printing side of things is a bit complicated as well what i had to do is figure out how to print my reference marks first and i did this with pla so i just printed those down those four points and then for the details i want to print onto the plastic i wanted to make sure that i didn't move anything so i inserted a z offset of 0.6 millimeters so it would automatically start printing 0.6 millimeters up from where i printed the pla reference so it wouldn't dig into the plastic too much and i found at this point that double-sided tape that i had on hand works way better than spray adhesive it's way less messy and the cleanup is a lot easier but it's still really strong did initially make a rookie mistake of not scaling the posts to be smaller than the laser cut holes and there's obviously still a little bit of scaling and accuracy issues so it didn't completely go down the posts that didn't really seem to matter the z offset worked really well and the layers looked like they were going really well down onto the pt sheet when i pulled it away though they started to come away and i don't know why i think with my previous test it might have been dug in a lot more or maybe i had more heat i don't know i'll do a little bit more testing but the ptg on this just won't come off at all but the ptg on this test was starting to come away so i didn't want to throw away this project so far into it so i got my soldering iron out and i just dotted around the details with little points of contact to melt it together and that turns our little frog into a very grumpy toothy looking frog abomination but it held really well together after that and i could assemble the mechanism and this is the final part i know it doesn't look like much but this is a culmination of a lot of trial and error this week to figure out a method of making a very lightweight but quite strong compliant mechanism uh for something that could be quite useful like in this case um a ackerman style steering mech after a while the life hinges really do loosen up but they're not getting weaker like life hinges do have a lifespan as the plastic bends it's going to slowly deform and slowly lose strength over time but for a small movement like this in a lightweight platform it's it's a trade-off that's totally worth it compared to having to use a fastener or hinge on every single corner i don't see that being possible in something like this so i'm going to take this idea forwards to make a little remote control car thing to really properly test it and i'm going to make a tutorial in future of how i did the whole final process because it is quite involved and there's a few things i want to finalize and tweak again making the ptg stick really well to the pt sheet i need to do that but again going back to the the coffee cups i really like this pla sheet that they're made out of and i'm going to try to track some down because this is a better and easier way to do it and the plastic's thinner so it's like 0.2 millimeters thick it might be better for some live hinge applications than the thicker pt but i don't know i'm going to have to find some and if you found this video interesting then maybe consider subscribing to makers movies whereas i aim to empower your creativity through technology and i look forward to seeing you again very shortly catch up to guys bye

Channel: Maker's Muse

Views: 361,422

Keywords: 3d, printing

Id: pMA7aWCoWJ4

Length: 15min 40sec (940 seconds)

Published: Sat Jul 24 2021