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Creality CR-X Pro J aycar Electronics kindly lent us one of their new 3D printers – the TL4411 Creality CR-X Pro. We recently reviewed the Anycubic Photon Mono 3D Printer (July 2022; siliconchip.au/Article/15380), one of the newer resin-based 3D printers. So this seemed like an appropriate time to see what is the latest in the field of filament 3D printing. As times have progressed, nearly all recent 3D printer offerings are pre-­ assembled or require, at most, attaching a few parts here and there. The CR-X Pro requires some assembly, but nowhere near as much as the older kits. In the Anycubic review, we mentioned that we had previously looked at other filament-based printers going back around 10 years. Those were the UP! in August 2011 (siliconchip.au/ Article/1132), the RapMan in December 2012 (siliconchip.au/Article/450) and the Vellemann K8200 in October 2014 (siliconchip.au/Article/8040). The latter two were both sold as fairly involved kits, requiring a lot of work to get them going, both in construction and calibration. This Creality printer is very much easier to set up, as we shall describe. If you are unfamiliar with how 3D printing works, we recommend reading the article “From body parts to houses: the latest in 3D Printing” in our January 2019 issue (siliconchip. au/Article/11367). Also see the glossary later in this article. Technical specifications 3D Printer 3D printers have come a long way in recent years and we are spoiled for choice in the range of filamentbased 3D printers that are now available. Jaycar offered to loan us a Creality dual-filament printer for evaluation, so we took the opportunity to look at one of the newest ‘kids on the block’. Review by Tim Blythman 44 Silicon Chip Australia's electronics magazine The Creality CR-X Pro is a dual-­ filament 3D printer with a nominal build volume of 30cm wide, 30cm deep and 40cm tall. The unit itself measures around 80cm tall, 50cm wide and 60cm deep. It accepts widely-available 1.75mm diameter filament (the extruder has a 0.4mm nozzle aperture). The box includes two 1kg rolls of PLA filament in red and yellow. There is also a collection of tools and spare parts in the pack, which you can see in Fig.1. All of this is good to know when shopping for a 3D printer, but there is much more than just the bare specifications. The CR-X Pro Creality has been around for about eight years and has produced several 3D printer models, including both resin and filament types. The CR-X siliconchip.com.au One nozzle, two filaments The dual filament arrangement is siliconchip.com.au Fig.1: The included tools and spare parts are comprehensive. Not shown here are a pair of side-cutters (for cutting filament), a pair of spare Bowden tubes and a USB cable. We didn’t need any other tools during setup or operation. The needle-like object is a tool for unblocking nozzles and comes packed in a large block of foam. Frame Bowden Tubes X-axis Motor Extruder 1 Nozzle Extruder 2 BL Touch Print Bed Z-axis Motors Power Socket & Switch Pro is an update of the similarly-­ dimensioned CR-X, an older dual-­ filament design. The CR-X and CR-X Pro are so-called ‘Cartesian’ machines, meaning that the X, Y and Z axes operate independently and at right angles to each other. One stepper motor controls the printing head’s left-to-right motion, including the nozzle (the X-axis). The Y-axis is forward and back, achieved by moving the printing bed. The Z-axis is driven vertically by two lead screws, one on each side of the bed. Fig.2 shows the general arrangement. The X-axis is carried on the Z-axis, moving up and down with it. There are other arrangements for Cartesian-type printers; for example, some might move the bed up and down (instead of the printing head) to form the Z-axis. Non-Cartesian types might use linkages or pulleys to combine stepper motor actions to synthesise the axes that the printer uses internally. The arrangement used in the CR-X Pro means that the Y-axis stepper must have the power to move the weight of the bed, while the slower-moving Z-axis carries the weight of the extruders and the X-axis. Other arrangements have pros and cons, but the configuration used here is quite common and simple to design and manufacture. The frame is made of aluminium slotted channel, with the base covered by a black powder-coated folded sheet metal cover. The frame is powder-­ coated in a similar colour. The resemblance to older designs such as the K8200 is clear, but the execution and appearance have come a long way over the years. The CR-X Pro has cleaner lines and is sturdier. The extruder arrangement is pretty standard. The extruder motors are fixed to the Z-axis and feed the filament tubes to the nozzle on the moving X-axis via flexible Bowden tubes. This reduces the weight that the X-axis is required to move. The Bowden tubes introduce a small amount of slack in the filament path (compared to an extruder mounted directly to the nozzle), but this doesn’t appear to be a problem in this case; the Bowden tube is another prevalent design choice in filament-based 3D printers. Y-axis Motor Bed Adjustment Base Touchscreen Card Slot & USB Socket Fig.2: the general arrangement of the CR-X Pro, typical of many filament-based 3D Printers. The X- and Y-axis motors move the nozzle relative to the heated bed, with the extruders driving melted plastic out as needed. The model is built up layer-by-layer as the Z-axis travels upwards. The heated bed helps the lower layers adhere until the print is complete. Australia's electronics magazine September 2022  45 Creality CR-X Pro: features & specifications Printer type: dual filament extruder Print area: 300mm x 300mm x 400mm Power supply: 480W Nozzle aperture: 0.4mm Filament size: standard 1.75mm (2kg PLA included) Filament presets: PLA and ABS Software: two slicer programs included Print bed: textured glass (heated) Bed levelling: touch sensor for automatic bed levelling and compensation Other features: power loss resume, minimal assembly needed simple but functional. A Y-splitter combines the filament paths from both Bowden tubes into a single ‘hot end’ and nozzle. The filament paths merge where both filaments are still cold and solid. We’ve seen a few other nozzle arrangements for dual filament operation, and they too have various pros and cons. Some have two completely independent nozzles. This allows for independent extrusion, with the downside that the vertical and horizontal distance between them must be accounted for. Also, the available print area is reduced due to the distance between the nozzles. When printing with dual filaments, the CR-X Pro manual mentions a reduced print area (down to 27cm by 27cm in the horizontal plane). However, this is due to the purge tower, which we’ll explain later. We’ve seen other nozzles that combine the filaments in the hot zone, allowing the filaments to mix at varying ratios. This is great for combining colours, but we expect it would be more prone to being blocked. The large mixing area also means that cross-­ contamination is likely. One reason we have heard for using two different filaments is that a support filament (see glossary) can be printed in a different type to the main filament. For example, water-soluble filaments exist, allowing the supports to be washed away. We don’t think the CR-X Pro will be suitable for such a use as there is some mixing of filaments in the nozzle, meaning there will always be some filament cross-contamination. Different filament materials often require different nozzle temperatures, and this is not always practical with a single nozzle that would need frequent temperature changes to achieve this. 46 Silicon Chip We can see the appeal of the simplicity in the arrangement used on the CR-X Pro, although it only allows for printing in two different colours of the same filament type. For those interested, the CR-X Pro uses the open-source Marlin firmware. Out of the box We received the 3D printer in retail packaging from Jaycar and were thus able to experience the ‘out of the box’ journey. Assembly is not complicated, but we noticed some things along the way that might help you if you are thinking of buying this 3D printer. Like many 3D printers, the CR-X is knocked down inside the box and requires a small amount of assembly to complete. Fig.3 shows what we saw on opening the box. Some aspects might not be evident if you have not used a 3D printer before. For example, the print bed is not restrained in its travel and might slide around if care is not taken when removing the parts from the box. It’s all doable by one person but will be much easier with someone to help. Additionally, the Z-carriage, which moves vertically in the assembled printer, is fairly well fixed in place as it runs on lead screws. But unlike the photo in the manual, the Zcarriage is fully lowered, and we found that it came in contact with the glass print bed during assembly, marking it slightly. Attaching the two parts is fiddly. Each side of the vertical frame is attached to the base by a recessed machine screw via the holes under the base. Yet the machine does not lend itself to being rested on its side. We recommend that one end of the base be rested on the edge of a bench, with the other end held up by a willing assistant. This gives access to the screw holes in the middle of the base, leaving two hands free: one to hold the frame in place while the other fits the screw from underneath. The included tools are quite complete and include a hex key for tightening these screws. The frame is remarkably solid despite having no reinforcement apart from the machine screws holding the channel pieces together. Other designs require triangular reinforcement members, but the CR-X Pro is rigid enough without them. The filament roll holders are a bit tricky to install. They use T-slot nuts in the frame’s channel. We suggest leaving off the spools until after the brackets are secured. Some cables connect between the frame and the base. They are easy enough to fit, but we found that the two Z-axis motor cables came close to fouling the bed mechanism. So we pushed the cables back into the base slightly to minimise the amount of slack, then used the provided tape to secure the cables flush against the base, as shown in Fig.4. Fig.3: the CR-X Pro comes well-packed. We strongly recommend having an assistant to help with the unboxing and assembly, as the printer is large and unwieldy, although not too complicated. Australia's electronics magazine siliconchip.com.au While the printer is powered down, it is possible to move the bed by hand, so you can easily check the clearances before powering up the printer. Simply slide the bed back and forth to confirm that nothing will hit anything. You can do a similar thing with the X-axis and check that the nozzle can move freely left and right. The print bed is glass with a textured coating on one side. Glass is an excellent choice for its flatness, and we found that the textured coating worked very well to promote adhesion. We previously found that polyimide tape (such as Kapton) is one of the best bed surfaces for adhesion. We tried that on the CR-X Pro, and while we would say that it worked marginally better than the textured glass, it was not by much. Certainly not by enough to go to the trouble to apply and maintain the tape. controller if done while the printer is on. We tested the USB connection and found no fault with its operation otherwise. But experience has taught us that this isn’t the best way to run printing jobs. Any glitch in the connection can easily cause a print to fail, so we ran all our test jobs from a micro SD card, eliminating any chance of issues with the computer or USB cable. Amongst the included parts is a micro SD card loaded with some demo files that you can print, but the printer must first be levelled and have filament loaded. BL Touch levelling which sits next to the nozzle assembly and probes the bed itself. During probing, it lowers a pushpin to measure the bed position, which it does by raising and lowering the Z-axis. Thus, BL Touch can also scan the bed and detect variations in Z height at different locations. Manual bed levelling can be done using four thumbwheels under the bed to bring the four corners into true. The firmware on the CR-X Pro can also map the bed’s surface at 25 points to compensate for minor variations across the bed. The thumbwheel alignment is helped by the AUX levelling screen on the controller, which can quickly move the nozzle between the four bed corners for calibration. The first thing we found when we powered up the CR-X Pro was that it makes a lot of sounds. There is a startup chime, and most (but not all) button presses are accompanied by a loud beep. There doesn’t appear to be an easy way to disable these. So try to avoid any midnight 3D printing! The interface is intuitive enough, and the manual details each screen and where each setting can be found on the various subscreens. We connected the printer to a computer using the included USB cable and found that this resets the internal One of the biggest challenges to getting successful 3D prints is having a print bed that is properly levelled. This is more than just ensuring that things are square to the horizontal axis; every point in the X-Y plane should ideally be at the same distance from the nozzle when the Z-axis is at its home zero point. Being too far away can prevent the filament from adhering to the bed properly, while being too close will prevent the filament from being properly extruded and can distort the lower printed layers. It could even damage the bed surface. Most of the older printers we have used have a mechanical limit switch testing Z-axis movement against the frame to detect that the Z-axis is zeroed consistently and correctly. Instead, the CR-X Pro includes the BL Touch auto bed levelling sensor, Fig.4: there isn’t much clearance between the thumbwheels and the wires for Z-axis stepper motors, but it turned out OK with some careful adjustment of the wires and application of the provided tape. Fig.5: the Z-axis compensation can be found on the Adjustment screen, which only appears to be accessible during printing. If the nozzle is too far from the bed, increase the compensation to bring it closer. The best time to do this is during the first layer of a printing job. First power up siliconchip.com.au Australia's electronics magazine Settings One critical point not mentioned in the manual is a subtle deviation from how older sensors (like the mechanical limit switch) worked. This could be a trap for those familiar with this arrangement. The BL Touch acts against the bed, so it doesn’t have a fixed, external point of reference like a limit switch would. So simply adjusting the thumbwheels does not change the Z height offset, which would otherwise be done by a small screw adjusting the position of where the limit switch is triggered. Instead, there is a Z offset parameter which is not mentioned anywhere in the manual, but is what sets the offset between the BL Touch and the September 2022  47 nozzle. You can find it on the Adjustment screen (Fig.5), which can only be accessed during printing. So the only way to set the Z offset is to start a print job and change it during the print. It’s a bit awkward, but we’ve had excellent results once we found this. We simply adjusted the Z offset until the extruded filament firmly adhered to the bed. That might take a few attempts, but we’ve found that if the printer successfully lays down the first few layers, all is probably well. So at worst, you might get a few prints failing very quickly until this is dialled in. Once it was set, we found that occasional minor adjustments were all that were needed. Another setting we adjusted was to turn off the auto-levelling on the Levelling Mode screen. We didn’t notice any difference between prints, whether it was on or off, except for the extra time taken to do the 25-point bed probe during every job. Since that can be triggered manually, we didn’t feel it was necessary at the start of every print. We were happy with the results when running the auto-levelling around once in every ten prints. Filament handling Loading filament requires that the nozzle be heated, and since the CR-X Pro includes two rolls of PLA filament, we simply used the PLA preset from the TEMP screen. The built-in power supply is a healthy 480W, so heating is quick. The PSU has a fan that cycles on and off. We found that this fan was the loudest aspect of the printer during operation. We timed it at about two minutes for the nozzle to heat up to operating temperature from around ambient on a cold day. The bed took around the same time to heat up. Using the trick of cutting the tip of the filament to a point, we had no trouble loading the filament, although you do have to be careful not to force both filaments into the nozzle simultaneously. The included red and yellow filament made it easy to see when one was retracted back into the Bowden tube. That might be trickier with a white or clear filament. Another way to tell is that the filament coming down from the rolls is slacker on one side (where the filament has been retracted) and 48 Silicon Chip Fig.6: with the front cowl loosened, the filament splitter can be removed using the included hex key tools (shown removed here). This gives access to the filament path through the hot end and nozzle, allowing it to be unblocked if necessary. tighter on the side that is loaded to the nozzle. We had a blockage early on, which we suspect might have been due to us not retracting one filament before loading the other. Fortunately, it was quite easy to clear. Two hex head screws hold the cowl surrounding the nozzle assembly; it is easily loosened, although the wiring means it cannot be removed completely. Nor should it, as the front-most fan should remain running to keep the heat break cool. You can gain access to the top of the filament path by removing the Ysplitter, similarly secured by two screws. Fig.6 shows the cowl loosened and the Y-splitter detached. The nozzle tip is simply unscrewed from below. The necessary tools are included, although the spanner to suit the nozzle is a simple open-jawed type. Because the nozzle must usually be heated when removing the nozzle tip (otherwise, it is effectively glued in place with solid plastic), do it with care. We’ve seen different spanners that hold the nozzle tip captive in a cup, and we think that sort of tool would be a better choice for the job. When we had a blockage, we pushed it out with the nozzle cleaning tool and checked that the filament path was clear with a filament off-cut. We managed to start refitting the nozzle tip by hand before it got too hot, allowing us to tighten it with the spanner. It’s easy to forget that some parts of the printer get pretty hot, so take care when working on it. A quick tip: if you install the yellow filament on the left extruder and the red filament on the right, the preview Australia's electronics magazine display in the software (described below) is accurate. In use With the filament loaded and the bed levelled, the CR-X Pro was ready to print. While there are three sample G-code files on the included micro SD card, we found that they were sliced with different settings than the defaults used by the Creality Slicer program. This meant they did not work as well as they could when we first tried to print them. Firstly, the bed temperature should be set to 60°C, but the sample files used a 40°C setpoint which resulted in warping and peeling. Secondly, the initial raft layers in the samples were also set to print too fast, meaning that the extruder skips and there are gaps in the raft. This resulted in many loose filament ends that caught on subsequent layers, as shown in Fig.7. This, in turn, revealed just how close the nozzle fans are to the bed. Any loose filament strands that protruded even slightly would catch on the fans as the nozzle moved around. The clearance is about 2mm, much less than many other printers. Once we had overcome these problems, it worked well. Proper cooling of freshly extruded filament is critical to accurate printing, and the fan location is likely critical to the CR-X Pro’s success. With these settings in mind, we restarted the sample prints, then manually altered the bed temperature and print speed from the Adjustment screen and got much better results. siliconchip.com.au Fig.7: some of the sample prints printed too fast on the critical first layer, causing gaps in the extruded plastic. On its own, this is not necessarily a problem, but we found that the curled plastic caught on the fans which hang low near the nozzle, causing parts of the print to lift. We did not have this problem with files we sliced ourselves. Although not noted in the manual, Jaycar’s product web page describes a ‘Resume Print’ function that saves print progress and can resume after a power outage. The manual says, “Do not plug or unplug the power cord when power on”, but we did so to test this feature. When we restarted the printer, it did indeed prompt us to resume the previous job and could restart it. However, it did not load the correct nozzle temperature, which stalled the restart. Manually setting the nozzle temperature allowed printing to continue. Fig.8 shows the result of the interrupted print. You can see that there was at least part of a layer that the printer missed. Whether that is a critical failure depends on your specific print job. At least you have the option to resume and don’t always have to throw the partial print away if power is lost. Software The included micro SD card comes in a small USB card reader, and it includes the aforementioned sliced files for the printer plus four additional folders. One includes a PDF manual. There is also a software folder with drivers and two slicer programs. Another folder includes a troubleshooting guide, while the fourth has several different models in STL format. We did not need to install any drivers as the CR-X Pro simply uses a generic virtual serial port interface, Fig.8: the Print Resume function can successfully recover a print after a power failure, but we found that the printer did not automatically load the correct nozzle temperature. It appears that the exact printer state is not stored, as we also saw a partially missing layer in our test. which most modern operating systems support by default. Remember that it is unnecessary to use the USB connection for printing, and we do not recommend it. We first installed the Creality Slicer software. Initial setup requires selecting a printer; the CR-X Pro is not shown, so we simply chose the CR-X option. This worked without any problems that we noticed. Fig.9 shows a screen grab of the Creality Slicer program. The manual explains how to use it, but it should be clear enough to anyone who has used a similar program before. The program is simple and functional. We had no trouble loading a model and exporting it. Printing with two colours was easily done by loading Fig.9: the Creality Slicer program is similar to many others. It allows the model to be placed, scaled, rotated and previewed before generating a G-code file for the printer to process. Different filament presets can be selected at top left. We used the Creality PLA settings: 200°C for the nozzle and 60°C for the bed. Note the estimated print time of 44 hours for a print of this size. siliconchip.com.au Australia's electronics magazine September 2022  49 two models, one for each colour. Many dual-colour models are distributed in this fashion. A right-click on the viewing area brings up a menu, and the “Dual extrusion merge” option combines the two. The “Save Toolpath” button at top left exports a G-code file that can be copied to the micro SD card to be printed. If a card has been inserted into the computer, you can save this file directly to the card. In any case, you really don’t need to do much apart from loading a model such as an STL file (by dragging and dropping, or from the File menu) and then clicking on the “Save Toolpath” button. Creality Slicer gives an estimated print time which we found to be consistently 20-35% low. For example, a two-colour print that was estimated to take 4 hours and 11 minutes actually took 5 hours and 19 minutes. A large single-filament print that was estimated to take 32 hours actually took 47 hours. So it doesn’t appear to be due to the time taken to change between filaments. The latter was the largest job we attempted with the CR-X Pro; it was a hollow vase about 25cm in diameter and 30cm tall, shown opposite. Objects coming close to the full bed size will take a very long time to print. The default setting uses a so-called ‘raft’ for bed adhesion (see Fig.10), consisting of several extra printed layers between the bed and the model. It uses extra filament and adds to the print time. Other operating systems Fig.10: the default Creality Slicer settings print a raft under the model, helping adhesion and reducing the effects of unevenness in the bed. It takes extra time and filament, though. This print took about three hours; the raft alone took almost half an hour to print. The included programs, including Creality Slicer, are for Windows only (being .msi or .exe installers). We created a working profile for the opensource Slic3r slicing program (https:// slic3r.org/) that would allow Mac and Linux computers to create G-code files for the CR-X Pro. Still, despite a bit of tweaking, our basic profile did not produce results as good as Creality Slicer at its default settings, which is a credit to Creality in ensuring that the printer and its software simply work. We feel that the defaults resulted in slower printing than we were accustomed to with other printers we used. Still, successful prints are more important than fast ones. Getting good results without hours of tinkering and adjusting is critical to lowering the barrier to 3D printing for beginners. That was missing from the earlier 3D Printers, but Creality Slicer is easy to use and is an important part of this. Cura Slicer software Fig.11: print jobs requiring both filaments use a purge tower (at left) to change filaments. We found that one of the sample prints also created these blobs, which caught the nozzle and occasionally resulted in a horizontal offset in the printed object. That didn’t happen with the models we sliced ourselves. 50 Silicon Chip Australia's electronics magazine Creality Slicer is based on Cura Slicer, a different open-source slicer program that Ultimaker maintains. Cura Slicer is also on the included micro SD card and can be used instead of Creality Slicer. There is a preset for the CR-X, which we used; Cura Slicer also currently siliconchip.com.au Glossary of important terms Axis Motor The X, Y and Z axes of a Cartesian coordinate system are driven independently by stepper motors in a typical 3D printer. The X- and Y-axes are typically coupled by toothed belts for speed, while the vertical Z-axis is often on one or more helical lead screws. Bed The surface onto which an object is printed. Depending on the printer, it may be stationary or move in one or more axes. It is usually heated to improve model adhesion. On the CR-X Pro, it is a textured glass surface that also aids adhesion. BL Touch A type of limit switch that uses a retractable probe detected by a Hall Effect sensor. On the CR-X Pro, it is used to measure the position of the bed relative to the nozzle moving with the Z-axis. You can also use it to map the bed to compensate for non-planarities. Bowden Tube A hollow, flexible tube that guides the filament from an extruder to the hot end and nozzle. It allows the extruder to be mounted remotely, so it doesn’t have to move with the nozzle, reducing the amount of moving mass. Extruder Usually a stepper motor driving a knurled shaft that grips the filament against a sprung roller. This allows the extruder to feed and retract the filament at a controllable rate. The spring allows the filament to be moved by hand if necessary, such as when loading and unloading filament. G-Code File A text file containing commands in the RS-274 CNC programming language. It is usually generated for a particular model of 3D printer by ‘slicer’ software and contains instructions that the printer follows to produce the object. Hot End The hot end is used to melt the filament. It sits directly above the nozzle and is typically a metal block heated electrically and monitored with a thermistor. It is accompanied by a heat break, such as a finned heatsink cooled by a small fan, to provide a sharp transition between the hot and cold parts of the filament path. Blockages can occur if hot plastic works its way into the cold part. Nozzle In the CR-X Pro, this is a pointed brass tip with a 0.4mm orifice through which the molten plastic is extruded. Its size dictates the smallest details that can be printed; it is mounted directly to the block on the hot end. Slicer A computer program that converts an STL file into a G-code file. This is known as slicing as the printed object consists of thin slices stacked vertically. Examples that are bundled with the CR-X Pro include Creality Slicer and Cura Slicer. STL File A file format commonly used for distributing 3D models. An STL file is usually generic enough that it could be printed on any 3D printer (within that printer’s limitations). Supports If any part of a model has an overhang (typically more than 45°), supports can be used to stop those parts from drooping during printing. The supports are printed plastic elements that can be broken away from the finished print. There is usually an option in the slicer program to enable supports for a given print job. 52 Silicon Chip Australia's electronics magazine lacks a preset for the CR-X Pro. The default settings are slightly different and present a few more options than Creality Slicer, but we did not find any significant differences in the printed results. In general, we found that the default supports Cura Slicer generated worked better and were more easily removed than those from Creality Slicer. On the other hand, the default brim (as opposed to raft) that Cura Slicer uses made for a rougher finish on the first layer. No doubt there are numerous settings to tweak all those things. We encourage new users to try both and see what they prefer; you might prefer Cura if you have used it previously or would like to delve deeper into the settings. Sample G-code Armed with better knowledge, we had another go at printing the sample G-code files. Even so, we don’t think they are a great showcase of the CR-X Pro’s abilities. There are three G-code files on the micro SD card. One is a yin-yang symbol (the file is named “taiji”), a great way to show off a dual extruder 3D Printer. Unfortunately, this was consistently affected by an odd but troubling glitch we didn’t see with any other prints. When the CR-X Pro changes between the two filament colours, it retracts the old filament and extends the new filament. It then runs what is commonly called a ‘purge tower’, visible on the left of Fig.11. An amount of the new filament is extruded onto the corner of the print bed. As this occurs on each layer, the result is like a tower. A large blob of filament is extruded on this tower for this particular model. We found that the nozzle would run into this lump (making a noticeable clunking noise). Occasionally, this would knock the nozzle off its position, meaning that subsequent layers were printed offset. With the smaller jobs we printed, the purge tower used at least as much filament as the printed object. So be aware when printing with two colours that the CR-X Pro will use substantially more filament. The purge tower is printed for every layer up to the full height of the model, whether a colour change is needed or siliconchip.com.au not. If it didn’t do this, there might not be a previous layer on the tower for the purge to attach, which would lead to loose filament and failed print jobs. The net result is inefficient filament usage. Fortunately, multiple models printed in parallel at the same time require only one purge tower, so you can save some filament by running many smaller jobs or copies simultaneously. The other two sample prints are so-called print-in-place mechanisms. That means there are interconnected moving parts that are printed in one job. A simple example of this is a gearbox. The individual gears and housing are printed together meshed, but are not fused. After being removed from the printer, they work as separate parts. One of the models (“tuzi”) is a rabbit head with jointed ears. The ears articulate quite well, but we noticed that despite the purge tower, the colours, especially the yellow, were not pure. The yellow was clearly reddened to varying degrees in different places. Some of the other files we sliced with Creality Slicer had a much larger (broader and deeper) purge tower. So we think the purge tower in this test print is simply not large enough. The third model is a folding cube (“fangkaui”) consisting of eight small cubes. It, too, is printed in one piece and can fold once removed from the bed. Like the rabbit, we found that it had inconsistent colouring. We also found that some of the joints did not work as expected, possibly because it has tight clearances. We also tried printing a pair of the included STL file models (from the “box3” folder) by running them through Creality Slicer with its default settings. That worked well, and we recommend that new users start with those models. Further observations We noted a few quirks while working with this printer. For example, the bed’s home position is at the front left, with the bed fully retracted to the printer’s rear. At the end of a job, the X and Y axes are homed, meaning that the bed needs to be moved forward to retrieve the print. Still, that is a minor point and could probably be fixed with some custom G-code. siliconchip.com.au This vase was the largest object we printed at around 25cm in diameter and 30cm tall. This print took a few days to complete, but large prints like this are a very good reason to get such a printer. At these sizes, printing artefacts are practically invisible. This heartshaped box is one of Creality’s provided STL files. It has printed well, capturing the detail of the flourishes within the resolution limits of the printer. The lid is a separate part that is a snug but neat fit for the base. Australia's electronics magazine September 2022  53 This is the test print that suffered printing errors (see Fig.11). You can see a step in the red part at the bottom. Despite the volume of plastic wasted in the purge tower, the colours still mix. You can see this in a comparison of the yellow of the top layer against the more pure yellow of the raft that is printed underneath it. Fig.12: the extruder mechanisms are solidly built but the filament feeds in at a sharp angle. This does not prevent smooth operation, but we saw these flakes of plastic being shaved off the filament as it passed through. 54 Silicon Chip Australia's electronics magazine As the filament feeds into the extruder, it turns sharply into its inlet, and we found that this caused fine flakes of filament to shave off. The sharp bend also places an added load on the extruder. Fig.12 shows the angle of the filament and the fragments that accumulate. This doesn’t seem to affect operation, but still could be eased by a guide wheel or perhaps another short length of Bowden tube. We saw one similar 3D printer where the owner had relocated the spools to the side of the frames instead of the top. That should be easy enough, as both parts are similar aluminium extrusions, and the sides should accept the T-slot nuts. That might help by bringing the filament in at a better angle, assuming you have the bench space to make the change. However, if you are using the full printer height, it might worsen as the extruder intake gets near its top. None of these points are major impediments to operation, but they are certainly opportunities for improvement. Conclusion Filament-based 3D printers have come a long way since our last review. We had no trouble printing in both single- and dual-filament modes. Even those who have not used a 3D printer previously should quickly find their way around the CR-X Pro, especially after reading this review. The common theme we have seen with the design choices in the CR-X Pro is that they are simple and effective, and they work. The Creality Slicer settings have been dialled in well and produce good results, although some users might find that they are wasteful of filament or slow. The included alternative of Cura Slicer is handy. 3D printers that just work are critical to ensuring that people new to 3D printing get the most from the experience. With some minor caveats, the CR-X Pro succeeds in this regard. Being based on solid hardware and the Marlin firmware means that the CR-X Pro is also adaptable. We expect experienced users will quickly refine a custom profile for the slicer program of choice. The CR-X Pro is available from Jaycar Electronics (catalog code TL4411) for $1299. SC siliconchip.com.au