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“Hands On” Product Review. We build the Velleman/Jaycar Electronics If last month’s ‘Electronex’ show is any indication, 3D printers are ‘the next big thing’ (if they’re not already!). Here we take a detailed look at the popular Velleman K8200 3D printer that you first build before you can print. Even one (optional) part of the printer itself can be 3D printed! 3D printers have now featured a few times in SILICON CHIP, some ready-built but some – probably of more interest to the typical SC reader – being for the home constructor. When a major electronics supplier such as Jaycar decides to stock a kit, you can be sure that they’ve thoroughly researched the market and decided on an item which will give maximum satisfaction and minimum difficulty. Team that with the European quality of the well-known Velleman company from Belgium and we’re off to a flying start! ably with a plain surface (ie, definitely not a shag-pile carpet!). You will drop at least one part of this kit on the floor during construction and that will probably be one of the tiny grub screws in the kit (OK, I speak from experience!). If the floor does not start off immaculate, you will never find that part. Now back to space. As you will find, the kit instructions frequently direct you to ‘take the bag labelled n out of the box’. The box contains 41 numbered bags and one or two that are not numbered, so finding bag n will not be a trivial task, especially when you start the build. Not for the faint hearted! You are also frequently directed to use a particular plastic First, a warning: This kit is not for Dad and Uncle Bert piece, which you can find ‘...in the bag containing plastic to throw together on Christmas Eve for young Billy to play parts’. This bag is crammed with all manner of strangely shaped components, which at first sight look quite different with the next day. The kit calls for a substantial expenditure of time and to those in the instructions, especially if you have them a although there are detailed and on the whole accurate different way up! The solution to both of these problems is to have enough and unambiguous instructions, mechanical and electronic skill as well as the ability to download and run a range of space to lay out all of the bags of parts and all of the plastic components. software are required. This is in addition to the space in which to build the These skills include a small amount of surface mount machine. For this last purpose I built a mobile trolley so that soldering, so all-in-all this is not a kit for the beginner. I could move the machine Having said that, the inaround as construction prostructions are extraordinarily gressed and get easy access detailed and accompanied by to any part of it. numerous photographs — in Finally, with regard to fact just the build phase is the work environment, the covered by over 850 photowork area should also have graphs in 20 chapters, and internet access, in my case a that does not include testing laptop machine. and setting up! For a long time now, nearly A clear space all suppliers have dispensed with those glossy instruction There are two environmenbooks that were such a pleastal things you will need if ure to curl up with on the you are to successfully build sofa or in bed. It is cheaper this kit: plenty of workbench space and a completely clean Most components are clearly numbered to make assembly to supply a CD or DVD. If the user wants a hard (read spotless!) floor, prefer- easy – but some are not, just to make life interesting! 14  Silicon Chip siliconchip.com.au The completed Velleman K8200 3D Printer from Jaycar. Putting it together is not something you’ll achieve in one evening (or perhaps even one weekend!) However, the instructions are very good – just don’t assume anything. . . copy it has to be printed at home. On-line instructions This kit takes this a stage further: The 3D printer kit instructions are on-line at www.k8200.eu/locale/ On-line instructions are an advantage to the user as well as the suppliers because they can be amended or corrected as necessary and the changes will take immediate effect worldwide. In fact, some of my suggestions and comments may well have been taken into account by the time you start building your own machine. First up we have ‘Start Building’ at www.k8200.eu/ manual/building where there are 20 chapters starting with Chapter 0, ‘Tools Required’ and ending at Chapter 19, ‘Assembling the Hot End’. These chapters can be downloaded as PDF files individually but I found it easier to work directly on-line; plus, there may be cases where the PDF has not been updated to synchronise with the on-line version. This happened to me when I downloaded the very last chapter — which turned out to be not up-to-date! My kit was supplied with a new pattern of extruder head (‘hot end’) thermistor which called for a different siliconchip.com.au assembly procedure. Although the website had special instructions for this, the PDF had not been updated. Velleman are aware of this via the forum (more later) and this may have been updated since. The tools you need The instructions start with an illustrated list of tools. Most of them are tools that any electronics person will already have: a screwdriver, wire cutters/strippers, a multimeter, soldering iron and solder and plastic tuning needle set. In relation to this last item, what is needed is not your normal IF core tweaker but a really tiny, plastic cross-point tuning/adjustment tool, for adjusting the motor control potentiometers on the controller board as part of the setting up procedure. Also required are some mechanical tools: a small file set, steel tape measure, digital callipers, metric Allen keys, a set of metric open-end spanners (you will need up to 13mm) and another vital item – circlip pliers. Circlip pliers This tool, essential on several occasions during the October 2014  15 build, is variously described as ‘combination snap ring pliers’ or ‘classic circlip pliers for outer rings (shafts)’. It is used to tension (hold apart) a circlip while easing it into a matching groove on the exterior of a shaft (or in this case a linear bearing). You may have never heard of or tried to use such a tool. It is tempting to try opening a circlip with ordinary pliers. From one who admits to once trying this years ago in desperation on a Sunday afternoon when all relevant shops were shut, in one word — DON’T! You will not succeed and you could either break the circlip, lose it altogether as it springs away violently, or badly damage an eye; possibly all three! In use, the correct tool engages in holes at the ends of the circlip and enables it to be opened enough to slip onto the shaft or bearing without risking breakage, blinding or other disasters. As well as the tools recommended, there are one or two omissions in the list. You will find a hot air blower (eg, a hair dryer) essential for heat shrinking the various sleeves to be placed over wire joints. If you wish to make sure you tighten the extruder nozzle correctly as recommended, you will also need a torque wrench that reads down to 3.5 Newton-metres as well as a matching 13mm socket. Also, I found it useful to have at hand a 30cm steel rule, scissors (for the bags) and small spirit level. Finally, you will need a small vice and (unless you have superb eyesight) a maggy lamp for the surface mount work. I also found a miniature high-speed handheld grinder set useful on one occasion. Before leaving the tools, I should also mention the soldering iron. The instructions specify ‘ceramic soldering iron 30W’. Don’t worry about ‘ceramic’ but the iron should have a very fine point (for the one excursion to surface mount work) and sufficient capacity to quickly solder various connectors and wires, so a 25/30W instrument is best. As for supplies, everything is in the kit except for solder - and it is also advisable to obtain some isopropyl alcohol from the chemist for cleaning the print bed later. At last – opening the box! With everything prepared and all tools at the ready, at last I opened the box, to reveal a very large assortment of parts, mostly in plastic bags labelled with numbers. The reason for the heavy weight of the box quickly be- It’s helpful to lay out the plastic mouldings. 16  Silicon Chip came apparent. Although the frame for this printer consists of cleverly designed extruded aluminium alloy members with various aluminium plates, a major item is the four heavy stepper motors which are the heart of the machine. The main moving parts of the machine centre around heavy stainless steel shafts. 3D printing – a refresher We’ve covered the operating principles of 3D printers before but for the newcomer I’ll briefly revise. The purpose of a 3D printer is to fabricate some solid object which can be any shape provided it fits into the available work-space and can be any material within the capabilities of the machine. For a home printer this is invariably a form of plastic such as PLA (PolyLactic Acid). Traditional fabricating methods are subtractive. That is, we start off with a piece of material, be it plastic, metal or as required. We then machine off chunks (typically on a lathe, mill or drill) and finish up with the shape we require plus a pile of shavings/filings (which in some cases can be recycled). By contrast, 3D printing is an additive process. For the typical home 3D printer, we start off with a plastic material (such as PLA) in the form of a filament a couple of millimetres thick and we draw it into a heated extruder head which melts it to a malleable state. It is then deposited on a heated printing bed in a thin thread to start to build up the shape we require. If you think of a conventional (or 2D) computer printer, it prints in two axes, side-to-side on the page (the X-axis) and up-and-down the page (the Y-axis). 3D printing adds an extra axis, the Z-axis, which adds vertical thickness. It does this by moving the relative position of the extruder head under tight control in those three planes. Note that the expression is relative position. In theory this could be achieved by moving the extruder itself in the three dimensions. In practice, in this particular machine, the X and Y movements are both accomplished by means of moving the printing bed (on which the fabricated object will be built) backwards, forwards and from side to side, while the Z-axis is dealt with by moving the extruder head up and down. The frame is constructed from heavy-duty aluminium extrusion which helps maintain precision. siliconchip.com.au SPECIFICATIONS: Velleman K8200 3D Printer (when completed from kit) Mechanical resolution: X and Y: 0.015mm (smallest step the printing plate can move in the X and Y direction)   (nominal) Z: 0.781m (smallest step the printing plate can move in the Z direction) Printing resolution: Wall thickness (X,Y): 0.5mm (nominal) Layer thickness (Z): 0.20 - 0.25mm Typical printing speed: 120mm/s Maximum print speed: 150 to 300mm/s (depending on the object to be printed) Extrusion nozzle: 0.5mm Extrusion thermistor: NTC 100kΩ Extruded aluminium profiles: 27.5mm wide Movement: 4 NEMA 17 stepper motors Linear ball bearings: 8 and 10mm Technology: FFF (Fused Filament Fabrication) for PLA and ABS FTDI USB 2.0 to Serial: Arduino compatible (Sanguino derived motherboard) Printable area: 200(L) x 200(W) x 200(H)mm Software: Repetier version 0.84 and up System Requirements: Windows, Mac or Linux computer to print from An internet connection for manual and construction instructions Power supply: 15V / 6.6A max Complete unit size: 620(H) x 500(W) x 420(D)mm Imagine now that we want to fabricate a box. We need to arrange that the molten plastic is deposited on the print bed in a line of the given length, then at right angles, and again at right angles, again a third time, coming back to where we were. So far we have a thin layer of plastic shaped like a rectangle. Now if we raise the extruder head slightly and repeat the process, the new plastic will be deposited on top of the old and we will have a slightly thicker line. Repeating this process over and over will build up the sides of our box. Clearly, we need to ensure that the plastic is extruded at just the right rate (and the right temperature) and that the printing bed is moved in the X and Y-axes while the extruder head is moved in the Z-axis – all under tight control determined by the object we want to create. This is accomplished mechanically by stepper motors, toothed belts and cogs, controlled by an electronic unit itself driven by software. In particular, this form of what we call CNC (computer numeric control) operation makes use of the G code. G code is a standardised form of issuing instructions to move tools by exact distances and in exact directions, as well as commanding such operations such as changing drills (CNC drilling machines), changing pens (CNC 2D plotters) or in this case, stopping and starting the flow of plastic from the extruder head. The stepper motor is a critical component in the movement in the three planes and in gradually building up the 3D ‘image’. As its name suggests, a stepper motor, rather than rotating at speed, rotates in a more sedate manner and often by just a small fraction of one revolution as instructed. Parts for the X-Y axis assembly. The X-stepper motor in position, held by hex-head bolts and square nuts. siliconchip.com.au The build Let’s now move on to the nitty gritty and start building. The first part of the machine to be built (at Chapter 1) is the simple spool holder assembly, which Velleman call the ‘coil support’ and which is used to support the spool of October 2014  17 raw material (plastic filament). This is not a part with any critical dimension or even function; indeed some printers don’t have a spool holder, relying on paying out the filament from a loose pile beside the machine. Once built, the spool holder is put aside until the machine is virtually finished. So I think the reason for building it first is to accustom the user to the method of instruction accompanied by the excellent illustrations. Actually I found that I tended to hit my face against the spool holder from time to time as I bent over the machine during construction, setting up and testing, so having fitted it when instructed I subsequently removed it until the machine was completely finished and calibrated. The instructions break down the construction of the printer into easy chunks and all follow a similar format. The user is first instructed to take an easily identifiable major piece (such as part of the framework) or a bag of given number, in which case the parts inside are clearly listed and shown, both in words (usually) and by means of a clear illustration. Usually, all the parts in a given bag are used in the construction step that immediately follows. In rare cases some of the parts are used later so before opening the next bag, if there are pieces left from the current bag they should be popped back in as the bag number will be referred to later. Follow the instructions! After the parts are listed, the detailed instruction for that step follow and often are accompanied by measurements where the rule or calliper comes into play. At this stage I should warn that the length of bolts is critical. If a 10mm M4 bolt is specified, don’t fit a 15mm one or else you will find a later step cannot be accomplished. I found only one case where I had to reduce the size of bolts, as advised in Chapter 9 (using a file) where in fact I used a small grinder tool. There are 20 separate chapters in the build section and a total of 858 high quality photographs accompanying them. These illustrations are not captioned as such but a glance further down the screen will reveal the photograph jpg number in each case. This is in the format of chapter/illustration, eg 004/043 for Chapter 4, illustration number 43. I have used the same convention when discussing the steps. Details of the X-Y axis assembly – linear bearings sliding on steel rods. 18  Silicon Chip One of the toothed belts. The first length to be cut is critical. Follow the instructions! Do you tend to skim (or even skip!) instructions and work by ‘common-sense’ like those people who proudly claim their method of testing an electronic item is to try using it before looking at the manual? That approach is not appropriate for this kit and will lead to much frustration as the build progresses. These instructions deserve very careful following to a precise degree. If a washer is shown under a bolt, that is where to place it and not under the mating nut. If the instructions say ‘do not tighten this nut yet’ be sure to follow them — there will be a good reason. Later, when you know more about what you are doing there may be one or two occasions where you can depart slightly from the exact instructions. Don’t force or over-tighten! If a part doesn’t appear to fit it is almost certainly the wrong part. Nothing should need forcing and nothing should require that last resort of the kit builder — the hammer! Also, if you are one of those ‘no half measures’ folk and especially if you often work on larger mechanical jobs like a car or bike, you must avoid over-tightening. Screwing up tight does not mean yanking the spanner with all your might until it’s locked solid. Smaller diameter nuts and bolts will need much less force than the larger ones. In this regard, the length of common right-angled Allen (hex) keys in particular is related to the leverage and force to be applied and for this reason I avoid those admittedly comfortable Allen keys with plastic T handles and rely on the traditional pattern of hex key as illustrated at the start of the instructions. How far to tighten small fixings is largely a matter of feel and sometimes sad experience! A guide is the state of the star (spring) washer that is on most nut/bolt assemblies. Where tightening is instructed, the bolt and nut should be tightened so that the washer (viewed from the side) begins The X-Y axis assembly assembled and sliding smoothly! siliconchip.com.au to be noticeably compressed but not screwed hard down so that it cannot be moved any further. I found that all the parts but one were of very high quality. The one exception was an adaptor that secures a threaded rod to the Z-stepper motor, which I found to be minutely eccentric, although perfectly usable. I did find that some of the aluminium plates had sharp edges in one or two places and this was improved by a very light application of a file. As you will find as the build progresses, the framework is made of cleverly extruded aluminium in which square nuts are located as required to locate numerous other parts, with the aid of cast corner pieces or plastic mouldings. The plastic mouldings are themselves of precision manufacture with no ‘slop’ whatever detected in fitting. The X and Y print bed movements are accomplished by moving the carriages smoothly with the aid of linear bearings running on precision ground bars. The Z movement is by courtesy of a rotating lead screw The copious instructions and photos are very nearly perfect. I’ll mention the rare problems that I found in the order that they occurred. One general anomaly is that although at first the terms ‘bolt’ and ‘nut’ are correctly used to mean male and female fasteners respectively (‘screw’ being sometimes used in Australia to mean ‘bolt’), they are reversed in some of the instructions (but not all of them). The illustrations make it clear when a ‘nut’ is really a bolt and vice versa! Linear bearings and circlips At 002/011 and subsequent illustrations in this chapter we have our first introduction to linear bearings. The plastic holders are of high quality as already mentioned but an even greater degree of precision is given by the inserted linear bearings which will later slide on the bars. These bearings are secured using circlips in grooves and it is worth repeating the caution that they should only be fitted using proper circlip pliers that locate in the circlip end holes. If you’ve never used circlips before, you need to remember that their flexibility is limited. The correct way to apply one is to engage the circlip pliers in the small holes, then offer up the circlip to the shaft or in this case bearing and gently squeeze on the pliers just enough to allow the circlip to slide onto the bearing, until it locates in the groove provided. Tension is then released and the I managed to break a belt clamp – fortunately there were spares. siliconchip.com.au clip should click into place. Aligning the bearings As instructed, you will not at first fully tighten the plastic mouldings onto the X-plate but it is helpful to align them by eye. This will be refined when the bearing bars are fitted, and the aim is to allow a smooth sliding movement over the bars, before attempting to tighten the fixing bolts. The same applies later with the other linear bearings. By 002/064 we come to the mounting of the first of the four stepper motors. This was one place where the design was found to be good rather than excellent, in that the wires to this motor pass through the aluminium plate that makes up the X carriage rather close to the edge of the provided hole (002/068). Care needs to be taken that the wires do not chafe here. When it comes to 002/072 and successive illustrations, you need to be very careful about two things. The instruction rightly emphasizes that there should be exactly 127 teeth in the 63.5 cm length of belt that you cut. The length of this piece of belt is indeed critical and the old adage ‘measure twice and cut once’ comes into play! Also you need to be careful tightening the clamp. Although mindful of my general warning (and previous experience), I still managed to over-tighten my belt clamp and break it. What I should have borne in mind is that the clamp presses against an inherently flexible material - viz rubber - and an even more gentle hand is required as tightening never reaches the invisible ‘wall’ that we instinctively aim for! Fortunately, spare belt clamps were included in the number of parts I had left over! Care with exact measurements A good example of the care that needs to be taken over the correct choice of plastic parts is at 004/008. In fact there are several pieces of very similar appearance but only some have the 10mm recesses required at this stage while others have 8mm. The illustration emphasises this in red. First anomaly In Chapter 7 I came across the first real anomaly. The instructions for fitting the Z-motor bracket are that the bottom of this bracket should be fitted at a height of between They look alike but some are for 8mm rods while some are for 10mm rods. October 2014  19 4cm and 4.5cm from the top of the frame, and illustrations 007/008 to 007/011 confirm this. But by 007/016 the bracket is shown level with the top of the frame, with the fitted motor correspondingly lower. That new position is shown in later illustrations such as 007/022. However, if you fit the motor in the lower position as I did, you will find that near the end of the construction it becomes apparent that the Z-axis end stop microswitch will not be actuated until the extruder head has collided with the print bed! The higher position is the correct one! Incidentally, the instructions preceding 007/008 emphasize the need to ensure that the Z-motor bracket is fitted perfectly horizontally. The reason for this is that the threaded Z-rod to be added to the motor spindle in due course will not fit or run correctly as it won’t be truly vertical if the bracket is even slightly out of kilter. This is where the spirit level comes in and by the way, it is not good enough to have the bubble ‘about’ in the middle of the sight. It must be exactly in the middle (assuming that the workbench itself is also level)! If the spirit level refuses to settle down, there may be a small manufacturing pip on the bracket (in which case carefully file that down). At 008/007 there is an instruction to ‘...take the short M5 bolt...’. This is better understood as ‘...take a short M5 bolt...’, since there are three in bag 28, as shown in 008/001. (The other two are used at 008/015 to 008/017). At 008/012 and 013, the instructions again indicate that the motor bracket should be perfectly horizontal. A small spirit level is of course helpful here – if not essential – but you may find that it is irritatingly difficult to set, as I did. This may well require a manufacturing pip to be carefully filed off so that the spirit level will seat correctly. At 009/068 the illustration shows Philips head bolts but those supplied in my kit were much better hex head ones, a sign that the instructions and/or kit are subject to continuous improvement. At 012/014 I found (for the one and only time) that the M3 bolt was just too short. I had to relieve a lip on the side of the microswitch as well as omit the flat washer. At 012/016, the illustrations show the microswitch secured through the hole nearest to the switch pivot. This was one case where I departed from the instructions as the far hole positioned the switch more appropriately in relation to the actuating screw on the X-carriage. Relief for electronic people The heated print bed. If not perfectly flat, it can be pressed until it is. Assembling the Z-axis bearing carriage. A bench vice is very handy here. 20  Silicon Chip At Chapter 15 we begin the all-important wiring process. Subsequent instructions call for the stripping and tinning of various wire ends, followed in due course by joining them. Since successfully soldering together two already tinned wires can require three hands, I have a preference for twisting joints together first and then soldering them. As you will see, all soldered joints are covered by heat shrink tubing. Most electronics enthusiasts have had the experience of soldering (often one of the older multiway connectors) and then realising that they had forgotten the end cap which should have gone on the wires first! This is the mistake you only make once or twice! Similarly, remember to place heat shrink sleeves over the wires before soldering joints. Again, clear and illustrated instructions are given to this effect. A minor anomaly in the instructions concerns the colours involved in the occasional need to snip off the middle wire on a three wire polarised header. For example, in 016/028 this is said to be orange but on my 3-way connectors the middle wire is in fact red, leaving orange and brown connected. In 016/035 the connections should therefore be (in the order of ribbon cable to connector cable): red --> orange, and brown --> brown. This also occurs at 017/021 and 018/057. 018/002 the instructions say ‘...twist the wires from Group 2 and 3 together’. It would be clearer to say ‘...twist the wires from group 2 together with each other as well as the wires from group 3 together with each other...’, as shown in 018/003. In 019/043 the larger heat shrink sleeve should be first placed over two wires from the hot end and not four. At the end of the build I had several parts left over. These included an extruder head thermistor (very thoughtful as this part is easily damaged), six square nuts, a couple of washers and in particular, quite a few plastic mouldings siliconchip.com.au (three of which were belt clamps, an easily broken part). There were no parts missing during the build, but despite being careful with recommended lengths I did run out of heatshrink sleeving just before the end (thankfully I had a stock). Setting up and printing We now move on the various tests, downloading and setting up software and finally printing an object! These activities are described under ‘Start Printing’ at www.k8200.eu/manual/printing There are seven chapters in this section, this time starting with Chapter 001 and finishing at Chapter 007. Chapter 001 The Basics: This is a brief summary of the basic principles involved in 3D printing. Chapter 002 Connecting the printer: This chapter starts with instructions on downloading the USB driver for the controller board, that for Windows being downloaded from http://ftdichip.com/Drivers/VCP.htm (at the time of writing, drivers for Mac and Linux were under development). This is a Zip file so be sure to extract before you try to run it. That process finishes with establishing which COM port will be in use for the controller board. After connecting the controller board to the computer via the miniature USB plug, you will find that red and green LEDs on the board come on. Once that is done, the next step is to download the main software for operating the 3D printer. This is found at www.repetier.com At the time of writing, the Velleman notes recommend using version V0.84, although the instructions may change in due course as there are now later versions available. This file is valid for Windows, Mac and Linux. The download process ends with the placing of the Repetier icon on the desktop. There are then detailed Repetier instructions for setting the COM port (which you have noted earlier) and various parameters on the printer, such as the dimensions of the workpiece, temperature of the extrusion head and print bed. Note that so far the controller board has not been energised (apart from incidentally via the USB port). The illustrations of the 15V DC power supply that follow (002/010 to 002/016) show the mains lead (after the outer sleeve has been stripped) being wrapped around a ferrite filter. The power supply unit that I received already had a filter built The Z-axis arm in position, with three guide rods. siliconchip.com.au in, so a much shorter length of wire had to be stripped. When connecting the power supply, at 002/019 there is a warning that if “anything happens when you do this, disconnect the supply immediately”. Certainly at this stage no motors should operate but in fact something should happen, and that is that the red and green LEDs (which come on when the USB port is correctly connected and configured) should now go off. When it comes to 002/025, Adjusting driver voltages, the parts involved are extremely small and you will note at 002/030 that three hands are necessary to carry out this task. The easiest — delegated to my assistant — was holding the negative probe of the test meter in contact with the negative DC supply screw. Extreme care is needed when holding the positive probe on each driver sub-board via, when the tip of the finest probe looks as delicate as a telegraph pole under a lens, in comparison with the job at hand! The actual adjustment of the driver voltage is very tricky. Unless you have just the right tool there will be considerable backlash. The recommended voltage is 0.425V but note that striving for the last digit is pointless. For example, an error of 0.005V here amounts to about 1% — meaningless — and ±5% (reasonable) would take the setting from 0.404V to 0.446V. Indeed, we are instructed that any of the three motor drives may be increased to as much as 0.550V (approximately 29% higher) if the motor mechanical linkages are too stiff for the setting first recommended. This is more likely on the Z-axis where the trueness of the threaded rod adaptor is critical. Tests We now come to tests via the Repetier software, notably movement of the motors and positioning gear. If you have wired everything correctly, then these are very satisfying and in my case went without a hitch. During this setup process (in 002/068) you are asked to move the print bed completely to the left. How far, I wondered? Against the frame or to line up the print head with the extremity of the bed? The answer is that it doesn’t matter at this time because the only reason for moving the bed to the left is to allow room to test the X-motor microswitch (on the right). Similarly for the Y-microswitch (at the back). When testing the Z-microswitch you have more time/room to carry out tests as The extrusion head carrier components, including the main bolt and bearings. October 2014  21 A small torque wrench with 13mm socket is advisable for setting the hot end. the Z movement when the lead-screw turns is much slower. Do not allow yourself to be distracted during these tests or failure to stop the motor travel may cause collisions or even injury! At 002/079 at the end of the tests on the Z limit microswitch, you are told ‘If the microswitch is working correctly the Z-carriage will stop.’ The X and Y movements do instantly stop when their respective microswitches are operated but the behaviour of the Z-carriage is slightly different. When the microswitch is operated it first stops and then immediately backs off (up) a couple of millimetres. This was confirmed as normal. Calibrating the printer In Chapter 3 we move on to calibrating the printer. As the instructions say, this stage is critical to good print quality. I did have problems here with my Z-motor stalling with a buzz when the print head was still some millimetres from the print bed — probably caused by the very slight eccentricity of my threaded rod/motor adaptor — despite resetting the Z-motor potentiometer to 0.55V (the permitted upper limit explained in just before 002/031). I worked around the problem by re-positioning the print head arm assembly down a few millimetres in the frame so that the print head was closer to the print bed while the Z-nut was not quite so far down on the threaded rod. I also found that my print bed was not quite flat which was initially frustrating. However, there is a critical sentence in the penultimate paragraph ‘The heated bed, cardboard isolator and aluminium bed plate can be forced a little bit until the bulge in the middle is gone.’ As advised earlier, brute force techniques should never be needed or employed in this build, and I found that judicious pressing on the centre of the print bed was effective in due course Configuring Slic3r There appears to be a minor error in the first sentence of Chapter 4, which reads ‘After you have calibrated your printer and printed...’. At this stage you will not have Starting on the extrusion head carrier. 22  Silicon Chip Some of the hot end components. In use they become hot! printed so those last two quoted words can be deleted. The configuration file K8200-PLA-STANDARD “download” will be found at www.velleman.eu, navigating via support > downloads where you will find K8200-PLASTANDARD.INI. This is a Zip file and you will need to extract it before loading it into Repetier as instructed. You now set the print, filament and printer settings to match the Velleman printer, save the settings and that’s the configuration done. The first print Velleman have chosen for the first print a fairly ambitious model, being a cover for the controller board on the printer itself. I say ‘ambitious’ not because the model is particularly complex but because it is fairly large, uses quite an amount of PLA filament and takes a long time to build. At 005/011 you are instructed to download the K8200BOARDCOVER.STL file, which you will find at www. k8200.eu/support/downloads or at www.thingiverse.com where it is thing No. 15524. STL can either stand for STereoLithography or Standard Tessellation Language and is the native 3D file that specifies the solid model exactly and in a form which Repetier can slice (via Slic3r) and interpret into the G Code that actually controls the printer. Again, this is a Zip file, so will need to be extracted. Pressing the LOAD button on Repetier now results in a navigation pane from which you can access the newly extracted STL file. Of course you are not limited to the one model! There are a host of STL files available on the net, an especially good selection being found at www.thingiverse.com/ Problems? For problems generally, you may find the answer on Feed mechanism taking shape! siliconchip.com.au 4DSC Oct Ad final.pdf 1 8/28/2014 11:26:31 AM % 5 1 SAVE UCTS ROD C 1 5 P D S 4 CTE : 4D SELE E n te r C o d e mber 201 s Expire st N o v e on 1 *Conditions apply INTELLIGENT DISPLAY MODULES A perfect solution for any design requiring a brilliance of color, animation or images on any application 4D Systems designs, develops and manufactures intelligent graphics solutions using the latest OLED and LCD technology available, with custom graphics processors that enable both stand alone and host dependent solutions suitable for a very wide range of applications and projects. NEW NEW NEW Picadillo-35T uLCD-220RD uLCD-35DT uOLED-96-G2-AR uLCD-144-G2-AR uLCD-32-PTU-AR DISPLAY MODULES for ARDUINO* Providing a quick and easy-to-use display solution for any Arduino project DISPLAY MODULES for RASPBERRY PI* NEW Broaden the variety of your Raspberry Pi projects by integrating a display solution uLCD-24-PTU-PI 4DPI-35 uLCD-28-PTU-PI DISPLAY MODULEs for bEAGLEBONE* Attach a primary display to your Beaglebone Black with a 4D LCD CAPE 4DCAPE-43 *Trademarks do not belong to 4D Systems. All trademarks belong to their respective owners. SC www.4dsystems.com.au 4DCAPE-43T www.facebook.com/4DSystemsAU 4DCAPE-70T www.twitter.com/4DSystems the excellent forum which can be found at http://forum. velleman.be/ There, beginners and old hands exchange information and you are likely to find a post from someone who has had the same problems as yourself as well as the solution. Conclusion This has been a marvellous journey lasting several days, and like many journeys the joy has been in getting there – making it – even more than in the successful arrival. Apart from very minor instruction anomalies easily overcome with commonsense, the instructions have been accurate, detailed and helpful. The copious illustrations – hundreds of them – have been extremely effective in clarifying the steps to take. I have no hesitation in warmly recommending this kit; the components are robust and extremely well made. Building the Velleman K8200 printer is a major project that will provide hours of enjoyment, a notable absence of frustration and will result in a practical machine which will reward continuing study and experimentation. The 3D printing world has not yet fully matured so you get a feeling of pioneering when using the finished item. At the same time this is no flimsy and partly thought-out kit. It will form a solid basis for further learning. Where from, how much? The controller board. All wiring terminates here, mostly on polarised headers. siliconchip.com.au The Velleman K8200 3D Printer we reviewed came from Jaycar Electronics and is available at all Jaycar stores, resellers and online (www.jaycar.com.au). The kit retails for $1299.00 (Cat No TL4020). SC October 2014  23