PLASTIC LIVING HINGES that NEVER BREAK with 3D Printing!

you were probably told that you need to make your 3D printed plastic leaving hinges thicker with a minimum of two layers but what if thicker living hinges actually break maybe you were also told a 3D printed living hinges cannot last for more than 50 Cycles but what if they can be designed to last for hundreds maybe even thousands of cycles look around why are all the living hinges around us really thin how do you design a plastic living hinge that can last for hundreds of Cycles even when 3D printed let's design the case and find out we will start by keeping things really simple and small to save time and reduce material waste the case will be 25 by 25 by 8 millimeters and the case will split down the middle now we need the top and bottom halves to align to each other as they close but these halves are free to slide side to side in front to back we'll add a lip to the bottom half and a cutout to the top half to locate the halves to each other great the bottom and top halves fit nicely together but they don't stay closed so we'll add a little tab to the bottom half to add some friction that will keep the halves together now the halves are hard to separate adding a little cutout on the bottom half will give room for the finger to grab the top half and separate it from the bottom half finally it's time to add the living hinge but where do you start the bend radius is the best place to start why a bigger hinge bending radius means you can make the living hinge thicker and a thicker hinge gives you more options for example you can use a more stiff material such as PLA and you might be able to print the case in two or even three orientations more on this later in contrast a small Bend IN Radiance means the livid hinge thickness will need to be small you might have to make the case out of a more flexible material such as unfilled nylon or TPU and you might get cornered into 3D printing the case in only one orientation to make it worse the living hinge will get very sensitive to the 3D printing settings you use and might even need to add extra feature to reduce stress in the hinge so let's just have the hinge located Midway in the case and see what results we will get now we want the plastic living hinge to bend easily and last as long as possible so we need a material that is flexible but we also want the case itself to be rigid so we don't want the material to be too flexible like this TPU so we will skip pla abs and TPU and go straight to ptg but wait there's this tough pla filament on paper it's 2.7 times more flexible than ptg I also happen to like tough pla more than petg so tough pla it is so Health takes should the hinge be but before we answer that if you need to restock your filament check it our affiliate links below whether you're looking for the lowest cost or high quality filament from vendors I had great results with in the past it's all there we may receive a small commission if you purchase from those links now back to the living hinge thickness my calculations show that the thickness should be a maximum of about 0.2 millimeters which also happens to be about the thinnest hinge I can reliably 3D print and I should be able to get close to 100 Cycles from a nice uniform hinge without any gaps and here's a 0.2 millimeter thick hinge it actually works although it does have some positional memory which means portions of the hinge are getting too much stress unfortunately the hinge quality is not that great the hinge is not uniform and there's lots of open space that wasn't meant to be there this is because the hinge is 3D printed in mid-air with no supports below to hold the shape of the hinge this is just a matter of the limitations of my fdm 3D printer adding supports will not help in this case either because the hinge will still sag due to the required small gap between the hinge and the support material without a gap the hinge and support material will fuse together and the support material will break the hinge the only way to get around it is with removable or soluble supports which I can't do at this time so let's increase the hinge thickness to 0.3 millimeters and see how it goes to my surprise it actually turned out pretty nice the hinge is fairly uniform with no gaps but there is one problem the actual hinge thickness is 0.4 millimeters which means more stress in the hinge so the hinge probably won't last for many cycles and the hinge broke on the 21st cycle obviously 20 Cycles is not good enough so let's look at the different ways to 3D print the hinge to see if we can come up with something better one option is to 3D print the case on the side so that the hinge is built up vertically this creates two problems one I have a 0.4 millimeter nozzle so the hinge thickness will need to be a minimum of 0.45 millimeters thick as we just saw 0.45 millimeter thick hinge will be too thick second the slicing software extrudes the hinge as a short line between the bottom and top case then it extrudes the top and bottom case outlines that touch the hinge line unfortunately this results in the hinge having a weak bond to the case resulting in a failure at the connecting points the second option is to 3G print the hinge directly on the bit which has two great benefits one it's possible to get a very thin uniform and flexible hinge and in fact I had a good success with getting down to 0.1 millimeter thick hinges although at 0.1 millimeter thick the hinge itself is very fragile second moving the hinge to where it can be printed on the bed results in a larger hinge Bend radius larger Bend radius equals less stress which means more Cycles so let's cycle test a 0.2 millimeter thick living hinge printed on the bed since it will be more durable and see how many cycles it will last for and I got you 300 Cycles without any signs of damage so I stopped the cycle test so yes 3D printed plastic living hinges can last for hundreds and probably even thousands of Cycles when designed in 3D printed correctly so skip the thick leaving hinges instead design thin living hinges and make sure to print them directly on the bed and make the bend the radius as large as possible to learn more about mechanical design watch this video

Channel: Engineers Grow

Views: 287,482

Keywords: plastic living hinges, plastic living hinge, living hinge, living hinges, 3d printed living hinges, design living hinges, design a living hinge, how to make a living hinge, make a living hinge, plastic living hinge design, what are plastic living hinges, plastic hinge concept, making a living hinge, living hinge minimum bend radius, 3d printing, plastic hinge, moving parts, hinge basics

Id: E2CqXgaQsyI

Length: 6min 6sec (366 seconds)

Published: Sat Mar 18 2023