Combining PLA and TPU in 3D Printing

Welcome back everyone. In this video I'm going to be covering different ways you can utilize combining TPU and PLA into one print. This is something I've been working on for quite a while and it has a lot of room to grow. Remember that I would definitely not consider myself a designer, so I just wanted to get this information out there to all of you more creatives out there to see how you can take this and run with it. Remember that most or even all of these tests do require multi-extruder printers, something like an Idex. I've been using the Sovol SV04 recently for these tests and think it works perfectly for this application, and it comes in at a pretty reasonable price. My review for that printer is linked to down below, but there are many other Idex options now available at consumer prices. Before continuing onto some awesome combinations of TPU and PLA, let's take a look at this video's sponsor. This video is sponsored by JLCPCB. JLCPCB is an industry leader for PCB boards, but they actually now offer a wide array of 3D printing services as well. This includes access to SLA, SLM, SLS, MJF, and FDM 3D printing. This means you can now have access to an affordable way to get the parts you require 3D printed, and you can get it done with the exact material and process you require, including very strong nylon, or even have it metal 3D printed. Getting a quote for a 3D print is extremely simple with their Instinct online quote tool. For this example, I'm just using a generic Benchy, but look how reasonable these prices are. To get this SLA resin printed is only $2.23 each. From my own experience, both using printers and working at a print farm, I have to say that these are some of the best prices I've seen for a 3D service. Most companies won't even start a job unless you're spending $100. And then I can even get a metal 3D printed Benchy for under $54. This might sound expensive, but anyone who's worked with metal 3D printing knows that this is extremely reasonable. And what is crazy is that we can get this SLS nylon printed for just $5. And these parts have really fast delivery. The printing normally takes 24-96 hours, depending on the technology and the size of your print, and then they ship right out. It's completely possible to get your 3D print delivered to you within just one week. New users can get a $54 coupon as well, which you can get by clicking the link in the description down below. Get industrial quality prints for the best price at JLCPCB. Alright, so I first started down this path when I was attempting to create a bulletproof print that was less than one inch thick. I have two videos on that that are now on my other channel, which are linked to down below. But my thought process was to try and create a composite 3D print similar to how bulletproof glass is made. Bulletproof glass is made by having layers of glass that shatter interwoven with flexible resin. This creates a composite that takes the high tensile strength from the glass and the high impact of the resin and combines them to make something that can stop a bullet. My thought process was to do the same thing with TPU and PLA. Standard PLA has a very high tensile strength, but has a very low impact resistance, as shown when I shoot the standard slab of it, or as I'm sure many of you have noticed when you accidentally drop a print. TPU, on the other hand, has an extremely high impact resistance, but very low tensile strength. You could chuck TPU-95A at the ground as hard as you can, and it'll just bounce. So during these tests, I utilized my Idex printers to do different combinations of thickness of PLA with thicknesses of TPU, all enclosed in TPU. None of these prints shattered, but rather bullets traveled straight through them as they would if it was entirely printed in TPU. I did have one test that I thought was a major success, where a 9mm bullet was stopped in its tracks and was actually stuck inside of the print that was less than 1 inch thick. Unfortunately, on this test, I didn't use a backstop, meaning that a lot of the energy was lost in the print by it being thrown backwards, and my retest with a backstop didn't end up working. That said, there is clearly something going on here that is making this composite print stronger than the individual PLA or the individual TPU. I'm still doing many more tests on this, and hoping I can figure out the right combination of amount of layers of each material, infill patterns and densities, and just overall patterns, but I sincerely think that we might be of creating some composite 3D prints with strength properties otherwise thought impossible. I'm hoping to have a part 3 to that video series within a month or two, so make sure you subscribe to that other channel. While I'm in the middle of doing these bulletproof tests, I also wanted to show off how we can combine TPU and PLA in other methods than just creating composite materials. We can actually create parts that are hard in one area of the print, and flexible in others. We can think of this like creating a flexible joint surrounded by TPU. Now, TPU and PLA does stick decently well together, at least to the point you can print them every other layer and they don't separate. That said, they don't stick perfectly, so if you do have a part with TPU in the middle of two PLA sides, it'll probably rip apart easily. This means that we'll require some sort of mechanical way to get them to stick together. As I mentioned in the beginning of video, I'm no designer and don't claim to be, but I thought of one simple method is to have these two materials bond together is to create a hook-like shape that goes from one material and hooks into the other. Here is my Mickey Mouse designing on Tinkercad, where I create the center slab of TPU that has hooks on it that go inside of the two PLA slabs so that they don't have a chance to come apart. I then bring it into my Sovol slicer for the SV04 in dual printing mode. I assign the right extruder and the two side slabs to be in PLA and the left extruder and the center slab to be in TPU and then merge the models together. Now this is when I think I screwed up because I decided to resize the large slab to a reasonable dimensions. I think that the hooks ended up not fitting perfectly inside one another when I resized the slabs, but these tests do prove the point that it's working as I thought it would. I ended up getting five failed prints due to clogs since I think one material was actually printing on another at the same layer height. I thought it might be because I was printing too fast or too cold, but I'm pretty sure it was the resizing that gave me this issue. Regardless, we can see that these parts combine two PLA slabs with a flexible slab in the middle and this is strong. The two side slabs just won't pull apart from each other no matter how hard I try. Now you can make this center slab to be as small as you want on your print and it'll just add a flexible joint to wherever you need on your particular print and the two materials won't come apart. Remember you can likely come up with a much smarter way to combine these two materials rather than just creating hooks on Tinkercad. I did want a successful print in this video though so I went ahead and created a new design without any rescaling. I used the legs from the Captain America with Mjolnir design by Kong on our Patreon and just made it so that the parts from the knee and below are in TPU and the thighs are in PLA. I do the same thing by creating hooks that mechanically attach the two materials together. Bring them both into the slicer and assign each their own extruder and then merge the models and this print didn't have any clogging issues or anything like that because I didn't rescale it. It did unfortunately take over 24 hours because it's pretty large, has a decent percent infill, and has a lot of layer swaps but I mean it overall came out great. Now I likely could have used a better print to split but this definitely shows off the possibilities. This connection between the black TPU and the white PLA is extremely strong. I actually broke the white PLA when bending the black TPU around but where the TPU and PLA are connected they just won't pull apart no matter how hard I try and that's from those hook connections. The PLA supports fell off of the black TPU without any effort and I've seen plenty of times that PLA and TPU can peel apart easily so it's definitely because of this internal connection for why they stuck together so strongly. I am sure you have projects out there that would benefit from a flexible joint and this is definitely a method you should consider. Now even though these two applications of a composite and a flexible joint will hopefully spark some creations out there for you guys, there are even more applications of combining TPU with other materials that can be pretty awesome. For instance take a look at these pistol grips. The stippling on the outside is in TPU and the bulk of the print is in PLA. Now if you use Prusa Slicer I believe you can just color each section that you want and in the material that you want to use but for these tests on Hoffman Tactical he was kind enough to separate each into their own STL for me to use on the Sovol Slicer. I mean this is actually really useful. It has a stiffness of PLA or PLA Pro depending on what you use and then the stippling has a little bit of give when in TPU. The blue is in TPU 90A and black is in TPU 95A and I think the softer 90A is even nicer. I am sure there are some cosplay items out there that would severely benefit from a bit of flex maybe something like a helmet where the inside is cushioned or I really don't know what you would think of. Overall I think that not only is TPU underutilized but combining two different types of materials is extremely underutilized in 3D printing. We can create any geometries we want so don't be thrown off by the fact one material has difficulty sticking to another material. I would love to see some insanely impact resistant stiff composites or flexible joints and applications I would never think of. If any of you are inspired by this please tag me in your creation so I can see it and maybe even make it for myself. Got a design that you are confident can be bulletproof? Also send it my way to shoot. My email is in my YouTube about section. I have already unsuccessfully tried a couple of people's designs but I'm still confident that it is possible. Thank you all for watching. I'll see you soon with more tutorials, reviews, news, and fun prints. Before you leave I wanted to show off the brand new version of my book 3D Printing Failures 2022 edition. It has been two years since I updated this book and this time not only have I made sure all of the chapters are relevant to today's market I also made sure the paperback version has full color photos. This should really help since the photo quality was the number one complaint from my past editions. I made it so that the first 120 pages or so are meant to be read in order so that you can get a full grasp of 3D printing especially if you're new to the hobby and then I have a diagnosing failure section. The goal is for you to compare my photos to the issues you're having and then direct you to the chapter that will help you fix your issue. Best of all Amazon for some strange reason has decided to mark off the price of my book by $11. I cannot promise this will last forever since Amazon couldn't tell me why they're doing it but this longer full color book forced me to charge $35 so Amazon listing it at only $24 is a great deal. Grab it now while you can all links will be in the description down below.