CEL-UK RoboxDual review

3D printing in a compact form factor

(Image: © Future)

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Over the four week test, the CEL-UK RoboxDual proved that it was still a very relevant machine and one that approaches things differently. 

The printer is a tale of two as it arrives with the option of two print heads; either the 'DualMaterial' or 'QuickFill'. 

Starting with the 'DualMaterial' with the two 0.4mm nozzles. Loading the filament into the system is easy enough with both Reels slotting onto the side of the machine and Reel 2 just standing proud. 

(Image credit: Future)

Even though the print head is dual material, you can still print single materials if you want. 

In the test, I printed a couple of dual material models to test the results, but for the most part, I found the dual extrusion was best used for more complex parts that required a support structure. 

The quality of the prints from the 'DualMaterial' head was good, and the test prints of 3DBenchy showed excellent overall performance with the three preset quality options. 

At the lowest quality, the result was good with some drooping of the filament on the boats front window, but other details were as you'd expect. 

At the standard setting, the 'DualMaterial' outputs the best quality prints with little to fault. Good accurate prints in PLA and ABS are possible with no stringing and again an excellent overall finish. 

Taking the quality up to the maximum, and the results did vary, all prints finished but under the bow some prints showed a little imperfection when printed with PLA, ABS prints were absolutely fine.

Used with support materials and while the surface finish may not match the likes of the Ultimaker 3 the machine is over half the price. Likewise, surface finish can't quite match the Prusa i3 MK3S, but then you have the advantage of proper support or secondary material. 

Either way, the slight compromise on surface quality is outweighed by the ability to print with two filaments. 

Switch to the QuickFill head, and although you lose the ability to print with the dual materials, the quality of the prints does increase.  

The low setting prints using the 'QuickFill' head we're fast and accurate, and the surface quality and speed was a real benefit, as was the increase in print quality which still not quite matching the Prusa i3 MK3S was not far off. 

CEL-UK firmly believe in the quality of printing and while PLA is widely used it isn’t the best material to use for general 3D Printing. Sure enough throughout the test while PLA prints were good, the quality of ABS prints was better. 

The present benchmark for print quality can be gauged with the AutoDesk print quality test. For this, I used the recommended eSUN PLA +, but CEL-UK does recommend that you should only use filaments approved for their printers. 

CEL-UK also recommend using ABS, PETG or HIPS for quality, but as the test states PLA the following show results from the eSUN material. 

Another note prior to starting the test, which the RoboxDual features an enclosed workspace when printing with PLA the door needs to be left open. In order to do this you need to switch off the safety in the Printing section.

There are seven parts to the test, and each is designed to evaluate the accuracy and quality of the printer. Unlike most printers, the CEL-UK RoboxDual comes with two heads the 'DualMaterial' and the 'QuickFill', which means that the test needs to be run twice.

QuickFill Head test

Dimensional accuracy - score of 4

In the model there's a stack of cylinders in decreasing diameters, each of these is measured in first the X and then Y axis. The results are then compared with the target measurement. The model produced the following average of the X and Y measurements.

  • Target 25 =  X: 24.90mm / 0.1mm Error | Y: 24.80mm / 0.2mm Error  
  • Target 20 = X: 19.88mm / 0.12mm Error | Y: 19.82mm /  0.18   
  • Target 15 = X: 14.98mm / 0.02mm Error | Y: 14.92mm / 0.08mm Error 
  • Target 10 = X: 9.92mm / 0.08mm Error | Y: 9.87mm / 0.13mm Error 
  • Target 5 = X: 4.83mm / 0.17 mm Error |  Y: 4.94mm / 0.06mm Error
  • X Error Average = 0.098
  • Y Error Average = 0.13
  • X&Y Error Average = 0.114

Fine Flow Control - score of 5

Measuring each of the spikes and it shows a length of 40cm. 

Fine Negative Features - score of 5

The negatives features test is a surprisingly difficult one to pass. Here as soon as the print was removed from the print bed, the 0.5 and 0.3 and 0.4 pegs fell directly out of print, this is good, with the second 0.3 and 0.2 also come away easily. 

Overhangs - score of 3 

Overhangs are not a strong point for the RoboxDual with any head or material, but the 'QuickFill' still manages an average score.

Bridging - score of 3 

Again bridging proves to be troublesome with the first three being clear.

XY resonance - score of 2.5

Look carefully at the markings, and there are no signs of resonance.  

Z-axis alignment - score of 2.5

The final check looks at the Z-axis alignment; there are faint lines but nothing to worry about.

Adding up the totals gives a final score of 25 out of 30.

Dual Material Head test

Dimensional accuracy - score of 5

Again it's the stack of cylinders in decreasing diameters, each of these is measured in first the X and then Y axis. The results are then compared with the target measurement. The model produced the following average of the X and Y measurements.

  • Target 25 =  X: 24.82mm / 0.18mm Error | Y: 24.74mm / 0.26mm Error 
  • Target 20 = X: 19.90mm / 0.1mm Error | Y: 19.95mm /  0.05   
  • Target 15 = X: 14.98mm / 0.02mm Error | Y: 14.88mm / 0.12mm Error
  • Target 10 = X: 9.77mm / 0.23mm Error | Y: 9.97mm / 0.03mm Error 
  • Target 5 = X: 4.78mm / 0.22 mm Error |  Y: 4.91mm / 0.09mm Error
  • X Error Average = 0.15
  • Y Error Average = 0.11
  • X&Y Error Average = 0.13

Fine Flow Control - score of 4

Measuring each of the spikes and it shows a length of 40cm, a solid string free result.

Exceptional Negative Features - score of 4

The negatives features test resulted in the 0.5 and 0.3 and 0.4 pegs falling directly out of print with the second 0.3 also coming away quickly. The 0.2, however, stayed lodged in. 

Overhangs - score of 3

Overhangs are not a strong point of the 'DualMaterial' head, nor do they need to be as prints can rely on a suitable support structure if needed. Here the printer managed the 45º overhang with the others showing dropped loops.

Bridging - score of 3

Again bridging proves to be troublesome for the 'DualMaterial' Head with only the first two being clear.

XY resonance - score of 2.5

Look carefully at the markings, and there are no signs of resonance.  

Z-axis alignment - score of 2.5

The final check looks at the Z-axis alignment; here, there are signs of lines on the vertical pillar.

Adding up the totals gives a final score of 24 out of 30.

Once the straight test was complete, it was then time to try out some more real-world tests. This is where the RoboxDual, and the choice of two heads comes into its own. 

Few other printers can offer that type of versatility, on the one hand, dual extrusion and on the other a high-quality prints with the 'QuickFill' head. 

I tested by printing the usual GoPro bike mount along with a tripod crown. The printer with the 'DualMaterial' head did an excellent job using the standard settings. 

The use of the support material made a more refined product and gave an overall better finish to the models. It also enabled the printing of structures that usually leave large scarring from supports. With the water soluble, PVOH filament used it was possible to print shapes and objects that would have otherwise been impossible, standard support structure or not.

Switching the head over to the 'QuickFill' and the quality of the prints was a definite step up in the finish, and the speed of printing was also increased. 

Ultimately the 'DualMaterial' head enables you to print objects that would otherwise be impossible or at least difficult with some sacrifice to the finished quality, while the single colour 'QuickFill' head produces decent quality prints at speed. 

The only area that some people might have issue with is the small print platform. It is smaller than most others on the market, but for most print needs it is more than big enough.

Final verdict

There are many reasons to like the CEL-UK RoboxDual; it's dual extrusion, single extrusion, enclosed print platform, and it's uniquely simple to use. 

CEL-UK also offers outstanding support, parts and upgrades which are all available if and when you need or want them. 

While this machine is excellent, some features need an update. The motor drivers are noisy, especially when you compare them with the latest batch of printers. 

The print quality from both of the supplied heads is good with the 'QuickFill' just taking the lead on overall print quality and then the 'DualMaterial' offering the convenience of dual extrusion. 

While the print quality is good, it's about average with the rest of the market, but with the advantage of huge material support made possible by those two heads.

At this price there are no other printers offering the features and convenience, a small amount of surface print quality loss is worth it for the overall usability and convenience. 

When it comes to reliability, the RoboxDual is a solid performer with the 'DualMaterial' head producing successive quality prints. Some issues with the models not sticking to the platform were quickly resolved once the calibration process had been run through. 

Both PLA and ABS materials printed well and ABS, especially benefited from the enclosed print space. 

(Image credit: Future)

At low and standard quality, both print heads produced excellent results, but where the 'QuickFill' was able to produce high-quality prints at the top setting, the 'DualMaterial' did show some quality issues. 

The RoboxDual is an incredible machine, but what makes it stand out is the ease of use and the ability for expansion. After all, the print platform is one of the smallest on the market; however, in use, the platform size is rarely if ever an issue and prints can be divided and printed in parts without to much fuss. 

What I did find was that as you have a smaller print area, I tended to divide jobs rather than attempt them in one. Rather than slowing down the print process, this actually sped things up, because if there was a failure it takes less time to print a part than it does a whole.

The RoboxDual, unlike many other printers, should appeal to a broad user base, from home users looking for a complete solution, to educators looking for a safe enclosed print solution, and businesses who need a scalable option. The RoboxDual is ideal.

Imaging Lab Manager

Ali Jennings is the imaging lab manager for Future Publishing's Photography portfolio. Using Imatest Master and DxO Analyser he produces the image quality tests for all new cameras and lenses review in TechRadar's cameras channel. Ali has been shooting digital since the early nineties and joined Future's Photography portfolio back in 2003.