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Construction by Jashank Jeremy Words and Photos by Ross Tester A 3D Printer that you first build . . . RapMan We’ve looked at a few 3D printers in the past but they’ve all had two major drawbacks as far as the average punter is concerned: object size and price! Here’s a 3D printer that can produce objects almost 200mm cubed . . . and you can buy for well under $2500. One teensy drawback of its own: before you create your first 3D masterpiece, you need to build it – the printer, that is! M any work experience kids get the raw end of the stick – while they experience “work” it’s more often than not the menial tasks, the drudge work that all businesses and companies rely on to keep going, like filing and posting – but many kids find boring. As such many go back to school disillusioned with what they might expect when they actually leave school and start work: what, no $200,000 a year job complete with expense account and company Porsche? Jashank Jeremy, a year 10 student from Manly Selective Campus (almost across the road from the SILICON CHIP office) was the exception to the norm. His luck was in when he came to SILICON CHIP for work experience: he was 10  Silicon Chip asked to build a 3D printer that was sent in for review. Build a printer? No kidding – you start with a (big!) box of bits and end up with a printer! And not just ANY printer, either. We’d been sent in a Bits-from-Bytes “RapMan” 3D printer by the Australian distributors, Benson Machines. So for most of the week Jashank was here, he was beavering away at putting the machine together. It was no reflection on him that he didn’t quite finish it to see it in action – he had to go back to school! Even if you’re used to putting together this type of equipment or are heavily into robotics, etc, you can expect to spend a good 30-40 hours building one of these, or even more if you’re not experienced. But more on the actual build shortly. By the way, the finished printer may not look exactly like the printers you’re used to. It doesn’t come in the traditional grey or bone case – it’s actually open-frame construction so you can see right inside the machine as the 3D printed image builds up in the centre. (See the sidebar, “How does 3D printing work?”). The “manual” The instructions to build the RapMan are something else again – it’s hard to describe just how good they are! Like the vast majority of equipment these days, there is no printed manual supplied with the RapMan 3D. However, there is a manual provided on CD (in fact, several manuals), with more siliconchip.com.au How does 3D printing work? information downloadable if you want it from the RapMan website (www. rapman.com.au). Of course you could print it all out if you want to but if you do so, you’ll miss out on one of the major reasons for viewing the manual on-line – it deserves special mention because it really is special! Each step of construction is very nicely illustrated but you won’t find a lot of text to read through. In fact, you won’t find much text at all. You won’t need it because the vast majority of illustrations are themselves in animated 3D. When you load the page of interest, the components you need (including the appropriate nuts and bolts, etc) are laid out for you for easy identification. But wait, there’s more . . . Click on the image and the components start “assembling” themselves, showing you exactly where each bit needs to go. You start with this rather large box of very-well-packaged bits and end up with a 3D printer! Don’t be tempted to willynilly break bits out: the instructions tell you which component you need and when. siliconchip.com.au We’re all used to printers that work in two axes – the print head moves across the paper in the X axis laying down ink where it is told to. When it reaches the end of the line, the paper advances up a little (the Y axis) so that a complete image is built up on the page line-by-line. Up to a point, 3D printers do much the same thing – although they don’t use ink as such, they use some form of plastic material which is extruded from the print head. In the case of the RapMan, that’s normally either ABS or PLA and this is applied significantly thicker than the ink in a normal printer. The plastic is heated to a liquid state and relies on a fan to cool, and therefore solidify, the material. What makes the 3D printer so different is that a third axis is introduced – the Z axis. Once a single-layer image is produced, the now-hardened image is moved down by its thickness and a new image, or layer, is printed directly on top of the previous one. The process repeats over and over so that (eventually!) a 3D image is produced. If you can imagine using a hotmelt glue gun with a fine nozzle to draw a circle, wait until it hardens, then draw another circle on top of the first, etc, etc, you’d end up with a cylinder built up of layers. That’s a rough approximation of the process. While this is the way the RapMan and similar 3D low-cost printers work; other (high end) printers lay down a thin film of special powder and then harden or “sinter” the required portions via the print head and repeat this, building up the layers. At the end of the print the non-hardened powder is brushed or blown away, leaving the hardened 3D image. The advantage of this method is that moving parts within the 3D print can actually move once the powder is removed. The latest RapMan can achieve a similar result by using two heads, one applying a softer (soluble) material which is relatively easy to remove from the wanted (hardened) model. December 2012  11 These five diagrams are actually screen shots taken from the superb assembly animation. Not only do they show you what goes where, as you “use up” the nuts and screws they disappear from the screen – if you have a screw short or over, it becomes very obvious that you have done something wrong! And here’s the really kinky bit. Even while the image is assembling on screen, you can twist and turn the image around to see what is happening on the back, the bottom, the top – in fact anywhere. Want to look at the illustration from the opposite side? Click on it and twist it around! Want to turn it upside down? Click on it and flip it – to whatever angle you want. Want it enlarged a bit? Easy. It’s not just a selection of angles or sizes, it’s all angles and all sizes, totally controllable by you and your mouse. And you can repeat this as many times as you like just in case you don’t understand something. Oh, if only life had been this easy when I built that model of the RMS “Titanic” all those years ago! (Yes, it was marginally before home computers were invented . . .). What you get Basically, for your two and a half grand you get a large cardboard box containing all the bits you’ll need to build the printer. That also includes the software to drive it (on the same CD as the manuals). It is very well packaged – in fact, the whole presentation is very professional, with lots of assistance in identifying the various components – even the nuts and bolts are clearly marked in individual packs so that when you need a “Xmm long type Y bolt and screw” you don’t have to flounder around for ages. The vast majority of the RapMan kit is built from various laser-cut shapes and sizes of acrylic parts, all attached to quite large carrier sheets (which are discarded on completion). If you remember building plastic scale models of ships and planes, with the various components stamped out on large carrier sheets for you to remove or “break out” as you built the model, that’s not unlike how most of the “plastic” bits are supplied for the RapMan printer. Of course, the bits are somewhat more substantial than were those hulls, decks and funnels of the Titanic! A word of warning here: don’t jump in willy-nilly and break out all the bits. They’re a lot easier to keep together – and identify – if they’re still attached to the carrier. Break them out only as you need them. All the bits are numbered so it’s quite easy to work out which bit goes with which. Along with the acrylic bits, there’s a reasonable amount of metal hardware supplied – the basic frame of the printer as well as the guides, worm drives and so on. Much of this is stainless steel so rusting shouldn’t be a major issue. The motors, which drive the print head in the X and Y direction and raise and lower the base plate (Z direc- tion) are also metal – but you might be somewhat surprised to find that the gears themselves are plastic. Surely this means that as they wear the printer will not be as accurate as when new? Apparently not – the worm drive system means that the wear and tear on the gears is minimised and accuracy is maintained. Before you start You’re going to need to refer to the construction manuals – often – so it will pay you to have a laptop/notebook computer within easy, close viewing so that you can easily refer to it. At the least, you’ll need a computer monitor and mouse/keyboard. And you’ll need quite a bit of work space to put the RapMan together. The finished item will be around 600mm square but we suggest you’ll want another couple of hundred mm around this to work with. And that’s not taking into account the large (610 x 410 x 170mm) box all the bits come in, which will also need to be close at hand. The workspace needs to be solid, flat and level (perhaps check it with a spirit level first?) and when some of the intricate bits are being assembled, you need good lighting. Did I hear someone suggest the kitchen table? Good idea – but remember that it’s going to take you at least a full weekend to put together (and Various stages during assembly: left and centre, Jeshank has completed the eight corner supports and has started fitting the stainless steel frame components. He’s actually moved off the bench and onto the floor to give him a bit more room! On the right is the mostly pre-assembled electronics module fitted and working. 12  Silicon Chip siliconchip.com.au What does it print with? The material used by the Rapman is 3mm diameter and is unwound from a spool by the print head as it is needed. By far the most common are PLA and ABS. From what we have read there are pluses and minuses for both but it would appear that PLA is best for the beginner/occasional printer. PLA Here’s what the finished printer will look like, with the major components labelled (no, your printer won’t be in pretty colours!) You’ll need to devote quite a bit of time – at least 30-40 hours – to complete the build. probably quite a bit longer) so if you can convince the family to forego meals for that long, good luck! Putting it together It really is quite simple to construct, given the outstanding assembly instructions which we mentioned before. And as we also mentioned, if you don’t quite understand how any of the bits go together, you can twist and turn the image on screen at will. You’ll start by assembling the eight corner clamps which basically hold the whole thing together. The first one will take quite a while but once you’ve done one, the rest fall into line pretty easily. You’ll then move on the frame – the stainless steel rods we were talking about before. The whole thing feels pretty flimsy at this stage but once tightened up properly and the cross-braces fitted, it starts to feel much more rigid. It’s as easy as XYZ! As a 3D printer, this not only has an X and Y axis, it also has a Z. The Z axis is actually the platform on which the printing occurs. First of all, a printed “raft” is laid down, then the print is built up on that. When finished, the object, with raft, is removed from the platform by inserting a thin flexible siliconchip.com.au blade under the base – the whole lot comes off and then the raft is easily removed. The X and Y axes use belt drives from stepper motors and captive linear ball bearings running on 12mm solid stainless steel rods. Overall the action is very smooth and precise. The Z axis relies on four threaded steel rods on which the platen is raised and lowered. Again, the action is very nice. The extruder One area we’ve seen a lot of (negative!) comment on the ’net is in the construction of extruders. It seems this is the one area where many users get into real difficulty. No such worries with the RapMan – it comes with this section prebuilt, ready to bolt into place. And the instructions to do this, once again, are superb. The extruder feeds the print medium at the right speed in the right place, not unlike an inkjet print head. But where the inkjet ink is measured in microns, the extruded plastic is quite a bit thicker – up to 0.5mm. The electronics Like the extruder, the electronics/ controller is supplied pre-built and tested. There are a lot of wires to con- PLA (polylactic acid) is probably the easiest material to work with when you first start printing. PLA is a biodegradable thermoplastic that has been derived from renewable resources such as corn starch and sugar cane. This makes PLA environmentally friendly and very safe to work with. PLA also has a very sharp glass transition point so if you use a fan to cool it, on printing it will set to solid very quickly. This has the advantage of achieving a greater range of geometries than are possible with other plastics. It also reduces the thermal stress on the printed part – warping becomes less of an issue in larger parts. Solid PLA is available in white, black, blue, purple, yellow and green colours. It does not require any curing or postproduction treatment. However, should you wish to, PLA can be sanded and coated with automotive spray filler. PLA can also be painted over with acrylic paint. ABS ABS (acrylonitrile butadiene styrene) is considered to be the second easiest material to work with when you start 3D printing. It is an engineering polymer commonly used to produce car bumpers due to its toughness and strength. It’s also the stuff that Lego blocks are made of…tough enough but safe enough for the kids to handle! ABS is suitable to make light, rigid, moulded products with good shock absorbance and wear resistance. It is available in white, black, red, blue, yellow and green colours and has a matte appearance. However, consideration must be made when printing larger objects – thermal stress can cause ABS to warp as the part cools. Other materials Other materials available for use with the RapMan (some for very specialised applications) include: High density polyethylene (HDPE), low density polyethylene (LDPE), polypropylene (PP), unplasticised polyvinylchloride (UPVC) and polycapralactone (PCL). December 2012  13 nect but again, the instructions make it relatively simple. About the only criticism I had here was the size of the display panel. The digits are uber-tiny (my guess is about 2 point type!). That might be fine for young, 20:20 eyes but old eyes like mine required a magnifying glass. The firmware required to drive the printer is also pre-loaded. It’s open source so there should be no future problems with updates or revisions. Finishing it off You need to follow a detailed procedure to make sure everything is tensioned/located/setup properly but if you do this in a methodical way, you should be rewarded with a first-timesuccessful printer when you connect power (a 12V plugpack, supplied) and turn it on. This includes threading the printing medium (PLA or ABS – see panel) – and it really is like a thread, supplied on reels which unwind as the medium is used. There are some pretty kinky colours available, including glow-inthe-dark types! When turned on, fans whirr, LEDs glow, the display appears and the print head goes through a self-test to ensure that it is in the correct position to accept printing commands from the software. Printing If everything proves satisfactory when you turn it on, there are a few test “prints” supplied with the manuals which you can try. It’s simply a matter of loading one of these onto an SD card and allowing the printer’s software to find it, then tell it to print. It really is that easy. Or you could download one of the myriad of STL-format files from the ‘net – there’s some rather amazing stuff out there. Just one warning here: a couple we tried didn’t print properly – no fault of the printer, the files themselves were corrupted. Of course, many users will want to build 3D objects using their own files. No problem: you simply draw a 3D model file with virtually any CAD package and save it as a stereo lithography (STL) file. This is then converted to a g-code to produce the layers which will be printed. Be warned, though: printing large and/or intricate objects will take a long time – many hours in some cases. Even simple objects may take an hour or more. So if you’re in a hurry, you’re going to be out of luck. The software All file preparation is done on your PC – but you don’t need the PC attached to the RapMan to print. The ready-togo file is transferred to the printer via an SD card. The PC software is called “Axon 2”. Upon loading it, you are presented with a 3D representation of the print area. You can then load an STL file containing the 3D model you wish to print and place it on the platform. You can also move, rotate and scale it. Clicking the “Build” button then presents you with a range of options. You can set the layer thickness (and thus print resolution) to either 1/8mm, 1/4mm or 1/2mm. The trade-off is that with lower resolution, you get faster printing. Another option is whether to print any “support material” under over- hangs, to prevent them warping – depending on the angle of the overhang and the type of plastic you are printing with, this may be necessary. If you get the multi-head RapMan 3D printer then you can use a different type of plastic for the support material than for the printed object, making it easier to remove. You can also change the fill density and pattern – normally, solid volumes of the printed object are not completely filled with plastic but rather have a cross-hatch or hexagonal pattern which gives them most of the strength of solid plastic without the weight or cost. The density is usually 20% but can be changed between 0% (hollow object) and 100% (completely solid). It’s also possible to change the print speed ratio. However, if you crank the speed up too high, the print quality could degrade. Once you have made the selections and click OK, the software then crunches for a while and finally displays what the printed object will look like, including the raft and any support material. You can examine it layer-bylayer and once you are happy, save it to a file which can then be placed on an SD card, ready for the printer. (By the way, one nice thing about the RapMan is that you can easily remove the print platform – just loosen a few bolts – good if you need to remove a large printed object from it). How big an “image”? Maximum printed size is approximately 200 x 200 x 170mm (w x d x h). This mightn’t sound all that big but for a printer of this type, it’s quite impressive. Maximum speed (depending on Scanning and 3D Printing Another intriguing example we found on the ‘net’ but this is a little different: intead of using a drawing, this uses a photograph and converted to a 3D image via software. The original is shown on the left, the 3D print on the right. This opens up a whole new realm of possibilities! If you’d like to know more about how this was done, have a look at http://cubifyfans.blogspot.com/2012/05/from-point-shoot-camerato-cube-printer.html 14  Silicon Chip siliconchip.com.au 3D printing that’s out of this world! Again, a 3D print we found on the net – just imagine an architect or designer being able to say “here’s what your new building will look like” and hand the client a scale model! the print head) is 15mm3/second. The most recent model (RapMan 3.2) can handle more than one print head which also opens up the possibility of multi-colour printing, as well as handling soluble support material, so complex shapes are made easier to build. Conclusion As you can probably tell, we’re rather impressed with this rather ingenious printer. At the price, it’s probably (though not definitely!) outside the budget of many hobbyists. That’s not to say that mechanically inclined hobbyists wouldn’t get a real thrill out of first building and then using the RapMan. What a Christmas present! But its most obvious market is in education – it’s ideal for schools, colleges and the like to not only demonstrate 3D printing but by building the printer first, students gain an excellent understanding of the hows and whys. We’ve even heard of colleges who have purchased a couple of these – and when each batch of students graduates, they disassemble them ready for the next lot to build and use. It’s also perfect for engineering and prototyping shops where they need to know if tab A really can fit into slot B – and then not just show clients a picture of what their new thingamijig will look like but give them one to actually hold in their hands! Another application we thought of (of course, there are many we haven’t!) is for the production of “bits” which may no longer be available – a specific knob or control part on a vintage radio, needed to match existing parts, for example. ABS is pretty tough stuff and, given the right software, the Rapman could produce a part probably as durable as the original. SC Where from, how much? Our RapMan 3.2 came from Benson Machines, 118 Carnarvon St, Silverwater NSW 2128 (Freephone 1800 68 78 98). Website for more information: www.rapman.com.au Recommended retail price (single head) is $2099.00 + GST. siliconchip.com.au An agile white vehicle roams the desert, manoeuvring the unforgiving terrain as the wind and sun beat down and temperatures swing from one extreme to another. NASA astronauts and engineers are test-driving a rover over rocks and sand, up and down hills in an environment that simulates the brutal conditions of Mars. This is Desert RATS (Research and Technology Studies) and the rover — about the size of a Hummer and boasting a pressurised cabin to support humans in space — is being put to the test. It could ultimately serve one of NASA’s loftiest goals: human exploration of Mars. In the nearer future, similar vehicles might help humans investigate near-earth asteroids. The rover is integral to NASA’s mission to extend human reach farther into space. Its cabin can accommodate a pair of astronauts for days as they study extraterrestrial surfaces. Its twelve rugged wheels on six axles grapple over irregular, unsure terrain. And its forward-jutting cockpit can tilt down to place its observation bubble low to the ground. 3D printed rover parts To design such a tenacious and specialised vehicle, NASA engineers drew on ingenuity and advanced technology. For example, about 70 of the parts that make up the rover were built digitally, directly from computer designs, in the heated chamber of a production-grade Stratasys 3D printer. The process, called Fused Deposition Modelling (FDM) Technology, or additive manufacturing, creates complex shapes durable enough for Martian terrain. When you’re building a handful of highly customised vehicles and subjecting them to otherworldly punishment, stock parts and traditional manufacturing methods aren’t enough. 3D-printed parts on NASA’s rover include flame-retardant vents and housings, camera mounts, large pod doors, a large part that functions as a front bumper, and many custom fixtures. FDM offers the design flexibility and quick turnaround to build tailored housings for complex electronic assemblies. For example, one ear-shaped exterior housing is deep and contorted and would be impossible — or at least prohibitively expensive — to machine. For its 3D-printed parts, NASA uses ABS, PCABS and polycarbonate materials. FDM, patented by Stratasys, is the only 3D-printing method that supports production-grade thermoplastics, which are lightweight but durable enough for rugged end-use parts. For more information: Tasman Machinery Pty Ltd 3/51 Grange Road, Cheltenham, VIC, 3192 Phone: 03 9584 8355 www.tasmanmachinery.com.au December 2012  15