<h1>3D Scanning and Printing</h1> <h4>Wednesday February 21, 2018</h4> <div style="width:45%; float:left"> <div style="width:100%; float:right"><video width="100%" autoplay loop controls><source src="https://i.imgur.com/AUHopXG.mp4" type="video/mp4"/>Your browser does not support the video tag.</video></div> <legend>"Mini Maker-Faire Eve! Launching one of the world's largest FabLabs tomorrow!"</legend> </div> ##The amble before the storm (a.k.a preamble) Ok, sorry I'm late with this one it's been a pretty hectic week! One of the most rewarding and in the top ten for lowest sleep-to-work ratio ever recorded in the history of under-25's. It was 3D-Printing week, we had the Mini-Maker-Faire event as the grand opening for the Super FabLab, and the two FabAcademy teams took out both 2nd and 3rd place in the Innovation Hackathon. Interestingly the locals allege that summer is coming up and this week we actually had clouds, wind and rain! In the desert?! Highly unlikely, but definitely a relief this week being crammed in a marquee and swamped by kids for most of the days. It was also super nice to chat with the kids exhibiting their science projects, and meeting the guys from OriginBase and TechShop - two maker spaces in our neighbourhood. The FabAcademy team took a few Ultimaker2+ and 3 Extended machines out to a) exhibit 3D printing to the crowd, and b) finish our assignments for that week. We were all very impressed with the work done by Francisco and the FabLabUAE team in preparing for the event, I watched as they last-minute CNC machined and painted the maker-robot (pictured right) and programmed Fiore's "Largest Arduino in the world"! <div style="width:45%; float:right"> <div style="width:100%; float:right"><video width="100%" autoplay loop controls muted><source src="https://i.imgur.com/9VzUHGZ.mp4"/>Your browser does not support the video tag.</video></div> <legend>"Mr. Red having a fun day."</legend> </div> ###Hackathon - Saviour Bracelet One of events to close the main event week was an innovation hackathon where six teams from around Dubai would compete for a <strong>20,000 dirham</strong> prize. Naturally, Wendy encouraged us to take part and I personally am going through some creative budgeting at the moment. There was a good representation from the Dubai Womens' College and others, then, conveniently residing in the Fab Lab, our class decided to participate as well. The hackathon's 'solutions' had already been selected from a precursor innovation competition where kids "no bigger than this here chair (points at chair)" submitted drawings of their technology ideas (Francisco, 2018). So the point of the hackathon was actually to <em>build</em> the solution as opposed to traditional hackathons where you would also be measured on the value proposition of the concept. The six ideas from the children were - <ul> <li>A prayer mat for the blind </li> <li>A traffic light system for children lining up at a water slide (yeah, what..)</li> <li>A bracelet with GPS for sending emergency distress signals</li> <li>A boat that eats up floating trash from a water body</li> <li>A camera that detects if someone has a disabled sticker on their car and blocks them from parking in a disabled bay if not</li> <li>An automatic animal feeder</li> </ul> From my interpretation, teams would be judged based on a) how close the implementation looked like the drawing, and b) how close the prototype was to production. <div style="width:33%; float:left"> <img src="media/week6/saviour-challenge.jpeg" style="width:100%; float:center; padding:5px 5px 5px 5px;"/> <legend>"The kid's original drawing for our hackathon team."</legend> <img src="media/week6/saviour11-design.png" style="width:100%; float:left; padding:5px 5px 5px 5px;"/> <legend>"Renders and original print tests for fitment and lighting."</legend> <img src="https://i.imgur.com/Q7XPS3N.gif" style="width:50%; float:left; padding:5px 5px 5px 5px;"/> <img src="media/week6/lights-test.jpg" style="width:50%; float:left; padding:5px 5px 5px 5px;"/> </div> The FabAcademy team was made up of 7 people and there was a team limit of 6 for this event so we ended up having to split into two groups, three and four in each. We ended up drawing names out of a box of pre-programmed FabISP boards (literally, we had all our boards sitting in a discarded chocolate box Wendy found) and the split became Salama, Abdulla, Zahrah and Eidha on the prayer mat idea and Darshan, Zubair and myself on the water slide idea. This was awesome, because each team had at least one dedicated mechanical person (Darshan, Eidha, Abdullah), electrical person (Salama, Carl) and then Zubair did software for our team and Zahrah did textiles for the other team. Two things I really **didn't** like though were getting handed the water slide idea and that our team were only a team of three. In other hackathon events I've participated in I've always enjoyed working with other people (especially local people if the event is outside of Perth) and so we decided to solve both problems by joining with one of the undersized Dubai Womens' College teams on the emergency bracelet. <div style="width:33%; float:right"> <video width="100%" autoplay loop controls><source src="media/week6/saviour-test-happy.mp4" type="video/mp4"/>Your browser does not support the video tag.</video> <legend>"Me, quite happy about the fitment and 'hella flushness' 👌 " </legend> <img src="media/week6/formlabs-form-resin-print.jpeg" style="width:100%; float:left; padding:5px 5px 5px 5px;"/> <legend>"Print test of the clear face component."</legend> <img src="https://i.imgur.com/VE9YQ0O.gif" style="width:100%; float:left; padding:5px 5px 5px 5px;"/> <legend>"Watching the Form2 print is so much more satisfying with clear resin."</legend> </div> They weren't able to contribute as much but since they were all app developers they did try to build an android app to interface with the bracelet. Plastics Engineer Darshan suggested we use the Formlabs resin for this print given how tight the packaging was going to be. And only after two days of Zubair and I mucking around with an ESP8266 and an Arduino mini, Hashim (one of the FabLab staff) showed us a secret weapon in the local inventory - An ESP12 dev board. These both turned out to be awesome pivotal moments for our design. Also, the most interesting thing about this event was that it wasn't FabAcademy, so we were allowed to use pre-fabricated boards and do anything we like! Also we could divide the tasks up according to our strengths unlike in FabAcademy where each person was required to demonstrate each skill. So initially I was against the idea of using the Formlabs resin because last time I had checked we only had black. But a secondary investigation miraculously yielded clear and white resins available! (Like checking the fridge when you're not hungry vs. when you are..) Over that weekend I produced 12 different CAD models, 6 prints, 4 prototypes with circuits and two presentation-ready devices. One of the incredible moments that happened for me was when I figured out you can reprogram the ATtiny85 microcontroller chip on a Lilypad Twinkle USING OUR FabISP PROGRAMMER! (Actually, I used Wendy's just to be sure). It was unbelievable - I soldered the programmer jumpers directly to the chip legs and I was absolutely gobsmacked that it worked! This whole time I thought I'd never need to use the FabISP ever again but there it was, rainbow cable and all, uploading the lights control and button activation program I had written! I can't believe I didn't realise what it was for 😅 With a light sand (800-grit, and next time would use a dust mask) the surface finish of the resin prints felt almost like a rubberised surface, and the part was flexible enough to feel comfortable on larger wrists. <div style="width:33%; float:left"> <img src="https://i.imgur.com/MJQPX2F.gif" style="width:100%; float:left; padding:5px 5px 5px 5px;"/> <legend>"Programming the Lily Twinkle (ATtiny85) with the FabISP we had literally JUST built and then forgotten about!"</legend> </div> I also added a few nice touches I've learned from designing and interacting with wearables like a magnetic clasp that wakes the device, a dual-activation alarm to prevent accidental activation, and a subtle fade with the battery indicator just so it doesn't look like I cut corners (even though I certainly did cut the corners off SOME circuits just to get it to package right!). Without boring you with the details here's a whole bunch of images illustrating our design process, and you can see the <a href="https://docs.google.com/presentation/d/1zQ-OF-HM72RiXzySnOiwnSxdkoTPWbXDjE-wnW53JLQ/edit?usp=sharing">presentation slides here</a>. The design files are included at the bottom of the page. We were super proud that both our FabAcademy teams made it in the top three, and definitely gave us a mixed up experience from what we were expecting from working as a team! The extra coin is going to come in handy also 😉 <div style="width:100%; float:left"> <img src="media/week6/inside-saviour.jpeg" style="width:33%; float:left; padding:5px 5px 5px 5px;"/> <img src="media/week6/soldering.jpeg" style="width:66%; float:right; padding:5px 5px 5px 5px;"/> <img src="media/week6/isp-esp.jpeg" style="width:33%; float:left; padding:5px 5px 5px 5px;"/> </div> <div style="width:100%; float:left"> <img src="https://i.imgur.com/r13pdhG.gif" style="width:33%; float:left; padding:5px 5px 5px 5px;"/> <img src="https://i.imgur.com/VFaJM1Q.gif" style="width:33%; float:right; padding:5px 5px 5px 5px;"/> <div> <img src="media/week6/in-circuit-programming.jpg" style="width:33%; float:right; padding:5px 5px 5px 5px;"/> <legend>"Programming and soldering the circuit within the bracelet was pretty adventurous. Also loving the glow and fade effects I added to the LED's."</legend> </div> </div> <img src="media/week6/second-place-carl.jpg" style="width:100%; align:left; padding:5px 5px 5px 5px;"/> ##What's this week about? <div style="width:50%; float:right"> <img src="media/week6/abs-3d-scale-print.jpg" style="width:100%; float:right; padding:5px 5px 5px 5px;"/> <img src="media/week6/3d-print-scale-test.jpg" style="width:50%; float:left; padding:5px 5px 5px 5px;"/> <img src="media/week6/3d-print-dimension-testing.jpg" style="width:50%; float:left; padding:5px 5px 5px 5px;"/> <video width="100%" autoplay loop controls muted> <source src="media/week6/3d-print-silver-filament-cropped.mp4" type="video/mp4"/>Your browser does not support the video tag.</video> <img src="media/week6/abs-brittle-cracking.jpg" style="width:50%; float:left; padding:5px 5px 5px 5px;"/> <img src="media/week6/3d-print-scale-test-2.jpg" style="width:50%; float:left; padding:5px 5px 5px 5px;"/> <img src="media/week6/nylon-3d-print-filament-abs.jpg" style="width:100%; float:right; padding:5px 5px 5px 5px;"/> <img src="media/week6/cura-ultimaker-only-just-fits-3d-print.JPG" style="width:100%; float:left; padding:5px 5px 5px 5px;"/> <legend>"The large box sections only just fit on the print bed when angled 45' x 45' "</legend> </div> So this week's tasks were to: <li>Characterise the 3D printers</li> <li>Print something that couldn't/shouldn't be made using a subtractive process</li> <li>Generate a model using a 3D scanning utility</li> Although I may not have really mentioned it, I'd actually been doing a bunch of 3D printing all throughout the <a href="assignment03.html">previous weeks</a> and in <a href="project01.html">making progress on the final project</a> . I had evolved from simple shapes, printing in ABS, printing in different orientations to improve surface texture and features, using the Formlabs machines (see the bracelet above) and now printing in Nylon. ###Nylon-plated box Because of my prior experience, I wanted to do something really special this week (but not too special). Making shapes is fun and all, but it's still quite basic and limiting. The art(s) of 3D printing only BEGIN at temperatures, speed and adhesion settings. There's plenty of development in the commercial 3D printer industry and I kinda felt the need to push these new developments to the limit. I'd been testing out my box designs since <a href="assignment03.html">Week 3</a> and <a href="assignment05.html">Week 5</a>, and had been working on solving a couple problems. I did this in 1/2 scale to save material and I'm also really impatient and want to see (and touch) the fruits of my hard work quickly and repeatedly. In a nutshell: <li>There was only limited orange ABS material and I was worried about running out/using it all up</li> <li>The ABS was delaminating like fresh pages in a book</li> <li>The ABS wasn't actually very strong at all around the bolt holes and when stressed <em>torsionally</em></li> <li>The weight of the part had to be kept low, but the strength needed to be very high (yeah, I know. I want high performance everything and I'm determined to have it)</li> <div style="width:50%; float:left"> <img src="media/week6/cybertech-sciaero-drone.jpg" style="width:100%; float:right; padding:5px 5px 5px 5px;"/> <legend>"Apparently not strong enough for my flying style though.."</legend> </div> <br> I'd just found a huge stash of Nylon filament in the cupboard and also read that it was the toughest stuff to print with. That is in both senses of the word - the most difficult, but also the mechanically most resilient. I've actually used 3D printed nylon before in unmanned aircraft I used to work on in Western Australia, where they used a Nylon SLS method to build their highly durable airframes. Pictured left, this is an airframe I repaired (comprehensively) after crashing it into a warehouse shelf (again, comprehensively) during initial training. Even though I needed to rebuild some parts of the shell, most chassis constructions couldn't survive an incident like that to fly another day. I initially did some tests to get the settings right for the new material - I figured higher temperature because it's stronger and stickier. Turns out it cools suuuper fast, absorbs a lot of water from the air, and is actually stickier when it's hot! So counter-intuitively, I had to drop the temperature slightly and turn off cooling fans. There wasn't much I was prepared to do about the water though, so that meant the settings continued to drift as I tested. One thing that most certainly definitely 💯% absolutement didn't help was printing outside. I mentioned in the preamble that we took the Ultimaker machines outside to print demonstrations during the Mini-Maker-Faire, and this most likely introduced condensated moisture from the grass in the marquee into the filament reel. When this happened, the most obvious thing I noticed was the surface finish and transparency of the nylon was a lot more 'frosted'. That's kind of annoying for a part that's got to look cool! Nylon as a printing material however, is.. like, impressively... elastic! It bends a long way before yielding which makes it perfect for this impact application! It's certainly not as stiff as the other materials, but it will take a beating before breaking permanently. It also adheres to itself REALLY well, meaning layer separation is never an issue. So much so that, even the support material is difficult to tear off. Be careful of this! For these reasons, Nylon is actually a great complementary material to ABS. When I put two and two together I realised that the solution to all my problems above was to dual-print a multi-material part out of ABS and Nylon. If that was possible it would basically be the holy grail of 3D prints as I know it. I would basically stop buying anything that wasn't Nylon and ABS. (Actually, I just love ABS because I've never been able to do it in my home labs, but a PLA and Nylon composite print would probably perform quite well too!) <div style="width:30%; float:left"> </div> So being in the Super FabLab is the first time I've even considered doing a dual-head print. We have maybe 10 Ultimaker3 Exteded machines all with dual extrusion and extra Z-height! To be honest I kinda wanted to stay away from it as I figured it was a gimmick for using soluble supports. However, since I'm here I figured let's go with it. To do this I had to run a couple tests to confirm some things: <li>How does Cura handle a multi-material model?</li> <li>Will the two materials play nice, and bond together in a deliberate way?</li> <li>How much longer does it take to print, seeing as we're swapping heads every layer?</li> <li>How on earth do I design a multi-material model for printing with two heads??</li> <br> I did a quick <a href="http://lmgtfy.com/?q=how+to+print+dual+extrusion+ultimaker">Google search</a> to find out how Cura likes it's models when performing dual extrusion. Then to do the first test I started with a rectangle with two materials. I used the split tool in Fusion 360 to turn one rectangle into two bodies. However since I was pretty interested in a variety of angled interactions, I made the split line angled and disjoint to see if there was any noticeable stress distribution difference when I performed destructive testing. Exporting *.stl files from Fusion is a breeze - you just use the 3D-print utility and select the body you want to export. You have a couple of settings available like mesh resolution, but generally you just click and save. Chucking the *.stl into Cura for slicing was a breeze too, there's a bunch of basic default settings and some rudimentary tools for resizing and rotating your part. Then you export the g-code slices to a USB or SD card depending on your printer and start the print. I was sitting in the marquee at this point and got pretty bored so I didn't wait for the print to finish and took it out after a few layers. Unfortunately because of the different stiffnesses in the two materials the two bodies separated after giving the composite part a simple twist. <div style="width:50%; float:right"> <img src="media/week6/printing-with-abs-nylon-multi-material.jpg" style="width:50%; float:left; padding:5px 5px 5px 5px;"/> <img src="media/week6/print-bonding-separated.jpg" style="width:50%; float:right; padding:5px 5px 5px 5px;"/> <video width="100%" autoplay loop controls muted><source src="https://i.imgur.com/7fvlK7N.mp4" type="video/mp4"/>Your browser does not support the video tag.</video> <legend>"The second print, or first part of the second test, if you will. The prime tower fell over so the snot from alternating extruders made a mess."</legend> </div> Looking closely at the joins in the failed part (and by applying some obvious plastics engineering fundamentals) the two bodies hadn't actually merged at all - they simply printed next to each other like a cold solder joint (bad). I had to figure out a way to get some good overlap going on so the next two parts were made to test some theories. The first of these secondary tests I designed was like the first (of the first test), but instead of simply dividing the body from the vertical view I used a second split line (of a similar style) from the side views. This would create four bodies but with adjacent adhesion planes in the x-, y- and z- axes. This part actually came out quite strong, as it wasn't possible to twist the shapes enough to get them to separate. The layers also overlapped in the parts of the volume that were slanted and I'm fairly sure this would have helped the surface adhesion. The second part (of the second test, or more formally the third test part) was just a curiousity experiment to see whether or not Cura was stupid enough to print two meshes if they coincided through each other. I drew two prisms, one entirely intersected with the other and set the larger one to ABS and the smaller one to Nylon. <div style="width:25%; float:left"> <img src="media/week6/overlap.jpg" style="width:100%; float:left; padding:5px 5px 5px 5px;"/> <legend>"Being a man of high science I endeavour to perform tests in a methodical but befuddingly continuous manner."</legend> <img src="media/week6/overlap-squish-test.jpg" style="width:100%; float:left; padding:5px 5px 5px 5px;"/> </div> Turns out Cura is ABSOLUTELY stupid, which is a great thing when it comes to automation because it did exactly the thing I instructed it to do and the overlapped meshes printed layer-by-layer on top of eachother. This meant that a volume of my part now had alternating layers of ABS and Nylon and naturally I would formally test what effect this has. On the 23rd of March at exactly around 1825h I performed a <strong>Squish Test</strong>* on part number two of test two. The Nylon and ABS alternating layers demonstrated significantly better elasticity and layer adhesion than the straight ABS, though no discernible changes in stiffness were observed. <em>*a particular form of compression failure test using a bench vice</em> This gave me confidence that what I had in mind could be done and with that I left it there to focus on the hackathon. The print time was also considerably higher - the extruder assembly moves to a corner of the printer where a lever actuates the riser for the second extruder. It does this so the secondary extruder doesn't crash into the part when it's not being used, which has always been a classic problem for most machines that were released with dual extrusion. This process, and the use of a prime tower (I'm not that fond of it but I also haven't given it that much time) adds considerable time to each layer and so I would expect prints to take 20-30% more time. I feel confident with this edition of Ultimaker however, to be left unsupervised for a large number of hours so I deemed that this wouldn't be a show stopper. After the weekend I discovered that Cura actually has this awesome setting for <em>Merged Meshes Overlap</em> for this exact job. What it does is alternate meshes that overlap, so instead of printing (interlacing) one part over another it finds the boundary between the two meshes and alternates each layer by x mm in each material. I was intent to try this out on a 1/2 scale print of a box corner which led me to my last question: <em>How in frickin' heck do I split the part in Fusion 360 to make a multi material model?</em> I <a href="http://lmgtfy.com/?q=How+in+frickin%27+heck+do+I+split+the+part+in+Fusion+360+to+make+a+multi+material+model%3F">consulted a friend</a> from way back and they gave me absolutely nothing useful. At a loss, I had to settle for an extended series of split operations shaving the beautiful orange ABS faces from the nylon skeletal structure. The first two images were successful enough tests on a print where I accidentally set the extruders the wrong way around. Ideally I'd want the nylon where the higher stresses were (in the skeleton) but it did demonstrate the successful bonding of materials. The third image is a print in progress of the correct configuration with the ABS as the presentation skin. It was still going at the time of writing. <div style="width:100%; float:right"> <img src="media/week6/dual-extruder-merge-setting.jpg" style="width:30%; float:left; padding:5px 5px 5px 5px;"/> <img src="media/week6/merge-multiple-materials.jpg" style="width:30%; float:left; padding:5px 5px 5px 5px;"/> <img src="media/week6/nylon-support-material-composite-print.jpg" style="width:40%; float:left; padding:5px 5px 5px 5px;"/> </div> <br> ####Update: Carl's radical print settings for ABS and Nylon and also just generally I'm gladly at the point with Cura now that I understand how and when to push the machines, having had a suite of Robo R1+ machines previously and now access to Ultimaker 3+ Extendeds and Ultimaker 2+'s. My objectives when printing are a little different (sometimes heretic) to the majority of others in the community. If you want fine quality prints, they can be done adequately with the default settings. However, my focus is speed, strength and efficiency. My rationale is that if you print fast you will learn more, and you're able to achieve larger and more functional prints quicker. I also hate wasting material (which also has a proportional relationship to time) and when it comes to strength - a part that fails is a waste of material. It's a convolved mindset, but it's taken me this far. There are a combination of settings that contribute to these, and the following are my learnings about settings. I'm glad to hear from anyone who has a different opinion too - I can only speak for what I've found. Also, I'll talk about a few of the materials I've used all at once - I think it helps to understand what physical properties affect how you should think about your settings. I have to put a disclaimer here - the settings here may not work for you, or the *may* work for a while and then one day they won't. I push my machines **HARD** and many print issues arise from being near the limits of the machine. Please only try this stuff if you're experienced, since you'll want to be listening to your machine, feeling it, watching the bead and generally keeping an eye on everything that's occurring. It's very common that I'll be with a printer for the first 10 minutes, adjusting settings and levelling out the fractional deviations in build plate angle (I spend a lot of time basically inside the printer while it's printing). Use this advice carefully, but mainly understand that in the right conditions you *can* cut down a 19 hour print into 5-ish hours. **Layer height** - Generally I use 0.3mm, and if I *really* need to I'll use 0.2 or 0.15mm. Going to 0.15mm literally takes twice the time (twice as many layers) and if I need accuracy I would work more on the speeds than on layer height. Usually people worry about the 'runout' on the extrusion bead but that is very rarely a problem mechanically when talking about 0.1mm, and especially in light of other issues like shrinkage and warping. Update: I found that for the Ultimaker 2 the optimum layer height is \*probably\* 0.24mm. It's a nice flat bead but still quite fast with no tearing at higher speeds. **Line width** - I try around 0.4mm for the outer and 0.3mm for the inner walls, but haven't done a lot of experimentation. It largely depends on the extruder that is fitted. I use a 0.4mm nozzle, and have tried it with varied types of that sized nozzle. This doesn't actually save any time, but the strength of the part is greatly increased by avoiding voids in the skin of the part. **Extruder temperature** - For PLA I will usually be printing quite fast, so I don't mind going all the way up to 250 deg for this. There is quite good layer adhesion but can sag a little on slender features. People often think 250 is crazy but PLA doesn't start to get brittle until 260 deg, and I'm running quite fast. In order to have the viscosity low enough to travel the speeds I do I need the highest stable temperature the material will handle. This isn't so much the case with ABS and Nylon however, ABS tends to dry out above 265 and Nylon gets too sticky causing draggy blobs of material. They recommend 240 and 260 for ABS and Nylon respectively. I run ABS at 245-250 depending on the aircon in the room and Nylon around 265, but slow down the surface speed for Nylon because of it's stringiness. Both materials I have to have the buil plate around 80 deg just to minimise warping and the risk of separation. PETG is one of my favourite materials, being a compromise between the properties of ABS and PLA. However, it's quite similar to Nylon in that it's sticky, so usually I'll print around 230-235 deg still quite a bit higher than the recommended 220. Once again this doesn't directly save time, but it does allow you to achieve higher speeds (thus saving time) and having excellent layer adhesion behaviour. **Outer Speed** - Nylon has good layer adhesion with itself when travelling slowly so generally I'll print around 10-20mm/s for good surface quality. ABS can go a bit faster at around 25mm/s, because it doesn't string up and loses heat less quickly than Nylon so it can form a nice bead even after the extruder has passed. I've never actually worried too much about outer speed with PLA - I'm often cranking the temperatures and manually winding up the speed of the machine after the first few layers anyway. I imagine I'd be printing somewhere around 50-60mm/s on the outer layer. PETG being sticky like Nylon usually prints well around 35-40mm/s. This is the single biggest contributor to your print speed, so if you're going to paint, bog or otherwise re-work your printed part afterwards (not sure why you would, but hypothetically) then you could afford to crank this up a little more. **Inner Speed** - The inner walls are not nearly as important as the outside, but you still need skin adhesion. So I'll generally crank this around double+ the outer wall speed. From memory, anything except Nylon can handle over 80mm/s wall speed at the right temperatures. Nylon I might run from 40-60mm/s depending on how important it is and how the machine is feeling that day. The major limitation to the inner wall speed is how good your feeder is at providing pressure and effective retraction. Too much feed rate will cause your feeder to skip and eat into the material, and at the speeds I usually operate at things go wrong very quickly. This is why I'll sit and listen for a while on at least the first job of the day. Inner wall speed also has a marked effect on your print time, but not nearly as much as outer wall. **Infill % and Speed** - I've never cared much for infill (I know, treason), and here's why. For majority of parts the mechanical load is transmitted through the skin and in bending. Hopefully, if you've read my <a href="assignment03.html">How to fillet parts and learn how to transmit other loads efficiently too</a> you'll get the idea that the loads going through the skin are *at least* an order of magnitude higher than any loads travelling through the part. I once had a customer complain to me that his part wasn't printed at 100% infill. Unfortunately for the complaints department I wasn't there to point out that the part actually failed at a stress raiser, as a crack formation propagated through the skin. Once a crack forms it doesn't matter HOW much infill you had. The part HAS failed. It's going to come apart any minute. So my recommendation is that for strong parts (obviously after you have filleted as much as practical) you should look first to increase the wall thickness. Maybe between 3-4mm for something ridiculous. If a part with 4mm wall thickness fails you were never going to solve the problem with infill. After all that ranting, the infill settings I use are around 10%, but I've gone as low as 3% and as high as 20%. This would probably apply to all materials. Except for Nylon (it's always Nylon) since it exhibits incredible shrinkage, sometimes wall thickness can get too thick causing the part to contract itself off the build plate. You let me know if you have a solution to that one, but Nylon is generally durable enough at 1-2mm wall thickness. I do have to give credit to infill though, where your part undergoes *direct compression*, or *twisting*, where I might print a test at 20% and see how it goes. The infill *can* somewhat significantly transmit load through the part in these loading conditions, but wall thickness first. As for speeds, since it's not a presentation layer and the skin doesn't *usually* undergo significant deflection I tend to print anywhere between 80-120mm/s. Faster for PLA because I'm always overriding the machine and cranking (sometimes 200% speed) and once again less for Nylon because it beads and then slingshots unconnected infill material around the internals of the part.. :/ Obviously if you're printing in a transparent material, or if you have lots of thin features I might slow this down a touch because the retraction doesn't really mean anything to the machine at these speeds. Infill can have a huge impact on your print speed. Consider that most of your part is going to be infill volume, a difference of 20% to 10% is hugely beneficial. Your part doesn't suffer that much for it, so do think about it next time you get to experiment. **Support % and Speed** - I feel a bit the same about support material as well, if you can't completely eliminate it then it's just the tiniest bit at the top of your part that needs it anyway.. For this I'll do maybe 5-12% support material at 100-140mm/s. Support doesn't need to be strong, the filament just needs to rest on it while it's waiting for something to connect to. So you might notice at these settings the support comes out as a see-through web of tiny filament strings but most of the time this is effective. One situation your support may need to be stronger is if the adhesion to the build plate isn't good. However the latest Ultimaker Cura release has an experimental feature to block support generation in certain places so perhaps that could be beneficial! **Travel Speed** - Most of the time I'll be travelling at 250-320mm/s. One time I ran an Ultimaker2+ with a loose belt at 250mm/s and then forgot about it and cranked the speed up 50%. The machine itself limited to whatever it decided is a good travel speed but it didn't skip the belt at all which was interesting. I also ran a Robo R1+ (the one with the moving build-plate) really fast and the next morning the build plate belt had skipped a tooth. I have also had tall, top-heavy parts fall over from moving the build-plate too fast. My first printer was a Replicator 2+ that would shake itself off the table. Three cases where travel speed *could* be an issue. Generally not though. Your bearings will long outlast it's machine, so I wouldn't be too worried about moving very fast. Sometimes, machines don't have an internal speed limiter and so they can skip their own belts. Watch out for that, especially if you're like me and manually dial the speed multiplier! Other times the travel time doesn't actually make up too much of the overall build time so it can be safer not to bother turning it up too fast. This setting I'm not really giving advice on, but you can see for yourself how much it impacts you if you hover over the time estimation in Cura. **Retraction** - I don't play too much with the settings, but generally YES unless you're using flexible filament. With flexible filament retraction doesn't do anything other than jam your feeder after the first minute. It's better to just go slower with the flexible filament because you're going to have ooze everywhere anyway. Otherwise, I generally put the retraction back about a millimetre from the default setting. I haven't noticed much of a difference. **Build-plate Adhesion** - I make on-the-fly adjustments to the build plate most days because someone could so much as *fart* near the machine and the build plate goes awry. Wendy once recommended that I use "brim" for tall or upright parts and I now swear by it. I've done between 8mm and 20mm of brim depending how insecure I was feeling about the machine that day. I'll also crank the build plate temps up on a job-by-job basis. I've used up to 80 deg for PLA which suffers a bit of sag but not catastrophic, and 100 deg for ABS and Nylon. Interestingly, even though Nylon shrinks like a sausage in a pan it sticks to the build plate incredibly well without assistance. It could be the way the plastic flows when it is bedded, I am unsure. It just stays, so long as the bed isn't cold. **Initial Layer Speed** - The single most significant indicator to print success. If I remember to do this, I'll set the speeds to about half the speed of the rest of the print. The slow adhesion layer really makes a difference, and prevents pilling or peeling up at the corners. I also won't manually crank up the speeds until this bedding layer is done. This step can be the single biggest time saver in the print process because if your print comes up half way through there's no saving it. You've just wasted a few hours and if you're lucky someone else's material. --- Hopefully this has given you a few ideas of how to push your machine to it's limit - probably the power supply unit if I'm honest. Your bearings and extruder will easily handle aything else you can throw at it. **Fail fast, fail hot.** <div class="row"> </div> <div style="width:40%; float:right"> <img src="media/week6/airplane-food.jpg" style="width:100%; float:right; padding:5px 5px 5px 5px;"/> <legend>"What is the DEAL with airplane food?" <br>-The OG Jerry Seinfeld</legend> </div> ###Dessert-scanning To have a play with 3D scanning technology we had two Sense sensors available in the lab. They were a little annoying to set up, I tried to plug in the first one I found and it didn't work. After about 40 minutes and many stern words about the software I hypothesised that that it had to do with the fact that there were two sensors in the lab. Since each unit has a serial code, perhaps the first scanner I picked up wasn't registered to the computer I was using. It turns out they'd been messed up while moving between the old FabLab to the Super FabLab so it wasn't a huge deal in the end, it just meant I had to get out of my chair and find the other sensor. Inefficient. Already having seen what 3D scanners can and can't do (at least for Wendy, Darshan and myself), we were at a loss for useful things we could scan. The FabLab had been feeding us some overly decorated airplane-style meals - each morsel packaged individually and presented as if it were _actually_ delicious. In a moment of boredom we were inspired to take some desserts back to the lab area and see what they would look like under the scanner. To my dismay, it was only after we had scanned the assorted confectionery that I realised the STL format doesn't preserve colour. But you'll have to believe me they looked delicious in full RGB! Also, since the mesh was raw from the scanner there's not much compression. Some came out at 10mb per model. I had to host these files externally on <a href="https://www.thingiverse.com/thing:2850376">Thingiverse</a>. The Sense scanners were made by 3D Systems and were shipped with a somewhat primitive educational-style software package. They are well known for being easy to use, so you just pick the rough size of the object you intend to scan and then scan away! To do this we made a turntable out of a painting stool, and performed it inside for even lighting. We also used a spotted fabric underneath the specimens to assist the scanner in visually recognising fine rotation. for smaller specimens we rotated the turntable from below, but for human specimens it proved rather hazardous standing on a rotating chair so we instead tried to move the scanner around the subject. The scanner didn't require precise movement, just so long as it was slow. You could also go one way around a person and then come back around and do the other side. The software seemed to adjust the mesh on the second pass so potentially with more experimentation we could have achieved sharper models by making multiple passes of the objects. <div class="row"> </div> Here's what we came up with: We started with my personal favourite, Spiky Dessert. Sweet spiky pastry with a dribble (drizzle?) of dark syrup. If you pick it up carefully enough, it even comes with some kinda crunchy macadamia-style nut on top. Delish! <img src="media/week6/spiky-dessert.jpg" style="width:30%; padding:5px 5px 5px 5px;"/> <legend>"Eidha looking quite keen for me to be finished with the Spiky Dessert"</legend> <img src="media/week6/spiky-dessert.png" style="width:30%; padding:5px 5px 5px 5px;"/> Next up not technically a dessert but it had an interesting pattern we weren't sure how it would turn out. "Chuck it in the scanner" we said. <img src="media/week6/scanning-quiche.jpg" style="width:30%; padding:5px 5px 5px 5px;"/> <legend>"Darshan just can't contain his excitement about this quiche."</legend> <img src="media/week6/quiche-scan-feat-table.png" style="width:30%; padding:5px 5px 5px 5px;"/> <div style="width:30%; float:right;"> <img src="media/week6/desserts-incomplete.jpg" style="width:100%; padding:5px 5px 5px 5px;"/> <legend>"Assorted desserts (some missing). Almost escaping in the top right is the strawbs specimen, and centred is the square pudding."</legend> </div> For those with a cream craving this was a cream-cheese-filled sponge topped with strawbs. Also one I enjoyed a lot. <img src="media/week6/cream-cheese.png" style="width:30%; padding:5px 5px 5px 5px;"/> Lastly for those who like tesselating desserts meet Square Pudding. Prefers late night conversations and staying refrigerated below 5 deg C. <img src="media/week6/square-pudding.png" style="width:30%; padding:5px 5px 5px 5px;"/> Before I leave it there, here's two special models you can download and use as maybe DnD or Monopoly figurines or something. <div style="width:50%; float:left;"> <img src="media/week6/wendy.png" style="width:100%; padding:5px 5px 5px 5px;"/> <legend>"Instructor Wendy Limited Edition."</legend> </div> <div style="width:50%; float:left;"> <img src="media/week6/zubair.png" style="width:100%; padding:5px 5px 5px 5px;"/> <legend>"Al Zubair Majestic feat. Artificial Plant."</legend> </div> <div class="row"> </div> We tried these scans two ways - the first time trying to maintain the subject on the turntable, and the second time just manually orbiting the subject. The second way proved safer and more steady, however the length of the cable for the sensor was an issue. There were anomalies in the mesh of course, especially after stitching and enhancing. Also when Wendy was standing the volume of the sensor didn't quite catch all of her so her hair is extrapolated. But I like to think she's just wearing a piece of paper 👍 --- ####A bit about Scanning using the 3D Systems Software Credit: Thanks to Wendy and Darshan for pulling out the old files from the computer back in Dubai after I left! <div style="width:50%; float:left;"> <img src="media/week6/scan-large.PNG" style="width:100%; padding:5px 5px 5px 5px;"/> <legend>"The software starts out asking what type of item you want to scan."</legend> </div> <div style="width:50%; float:left;"> <img src="media/week6/scan-size.PNG" style="width:100%; padding:5px 5px 5px 5px;"/> <legend>"There's three sizes for objects, like in that book about Goldilocks."</legend> </div> <div class="row"> </div> <div style="width:50%; float:left;"> <img src="media/week6/start-scan.PNG" style="width:100%; padding:5px 5px 5px 5px;"/> <legend>"When you start scanning it detects the object from the background, and a mesh begins to appear."</legend> </div> <div style="width:50%; float:left;"> <img src="media/week6/lost-tracking.PNG" style="width:100%; padding:5px 5px 5px 5px;"/> <legend>"If you move too fast or there the sensor gets distracted by a pretty girl in the background it loses tracking."</legend> </div> <div style="width:50%; float:left;"> <img src="media/week6/scan-coverage.PNG" style="width:100%; padding:5px 5px 5px 5px;"/> <legend>"As we rotated the turntable the mesh begins to close up."</legend> </div> <div style="width:50%; float:left;"> <img src="media/week6/scan-rotating.PNG" style="width:100%; padding:5px 5px 5px 5px;"/> <legend>"You can actually move the sensor up and down also to get overhangs and erroneous holes in the mesh."</legend> </div> <div style="width:50%; float:left;"> <img src="media/week6/scan-rotating-2.PNG" style="width:100%; padding:5px 5px 5px 5px;"/> <legend>"You can do a couple passes if the first one wasn't good enough, and the mesh converges."</legend> </div> <div style="width:50%; float:left;"> <img src="media/week6/scan-full-coverage.PNG" style="width:100%; padding:5px 5px 5px 5px;"/> <legend>"Nice one. <br>Almost sealed up."</legend> </div> <div style="width:50%; float:left;"> <img src="media/week6/model-with-holes.PNG" style="width:100%; padding:5px 5px 5px 5px;"/> <legend>"Once you're done scanning you get to see the mesh that came out. You can pan, zoom and orbit as you would expect."</legend> </div> <div style="width:50%; float:left;"> <img src="media/week6/mesh-filled.PNG" style="width:100%; padding:5px 5px 5px 5px;"/> <legend>"There are a number of post-processing options that allow you to close the mesh (usually for 3D printing purposes)."</legend> </div> <div style="width:50%; float:left;"> <img src="media/week6/enhanced-mesh.PNG" style="width:100%; padding:5px 5px 5px 5px;"/> <legend>"The enhance function is pretty subtle but I think it enhances edges and shadows. Perhaps some anti-aliasing."</legend> </div> <div style="width:50%; float:left;"> <img src="media/week6/restart.PNG" style="width:100%; padding:5px 5px 5px 5px;"/> <legend>"Ater you save up the model you can start over. Unfortunately saving the *.stl's doesn't save colour, and also the compresson isn't that good so the file sizes come out huge."</legend> </div> <div class="row"> </div> --- ##Design Files Design files for this week can be found at <a href="design-files.html">Design Files</a>. The STLs from Scanning can be found at <a href="https://www.thingiverse.com/thing:2850376">Thingiverse</a>.