CEL Robox – 3D printer review

CEL Robox is one of Kickstarter’s brightest stars. A small, compact 3D printer, by a British company C Enterprise Ltd., in December 2013, was granted £ 280.891 of funding, nearly three times the requested amount. What distinguished it from other similar devices, was a number of unique features characteristic of solutions found in professional machines of the Stratasys class. A closed (though unheated) build chamber, an innovative system of two printheads, chipped, dedicated filament, proprietary, super intuitive software and a 3D printing layer just 20 microns high (0.02 mm). And all this for just £ 999 (approx. 5500 PLN)! No wonder that when Mirek Jaskułowski of Printila / druk.xyz asked me at the beginning of this year to test this device, I did not bother to conceal my excitement. Unfortunately, it quickly turned out that the promises made on Kickstarter were one thing, while the reality was a whole different one…

CEL Robox is without doubt one of the biggest disappointments I have experienced when working with 3D printers. During the tests, it was the first time that I had a serious dilemma which model to choose for testing, because virtually everything I printed on Robox came out bad… or not at all. There is a serious possibility that the machine I got was defective – the multitude of problems I experienced while using the 3D printer was unheard of, which, in the context of very positive articles about it on various websites, made me feel confused and embarrassed.

Robox is a 3D printer full of contradictions – on one hand it has some truly fantastic capabilities that make working with it very easy, and on the other, the same features spoil the prints, and consequently prevent any work at all. It is tailored for the mass market customers, who should have no problems with handling it, yet the problems which occur during printing would puzzle even most experienced RepRappers. Finding the right settings to resolve the problems is no mean feat.

Finally, I approached the issue in a rather uncompromising manner – since the 3D printer is presumably simple and it is supposed to work on default settings, I used only those default ones, without going any deeper into the advanced settings. I figured that as long as nothing was written about an issue in the manual, I would not change or modify anything. Ii is possible that had I spent enough time with the machine, to conduct more experiments which would preclude any further errors and shortcomings, I would have been able to get better results in the end. However, this is not what is promised in the device’s advertisements, and even if we were to accept the reality, how would this “fantastic” machine differ from a typical RepRap then…

CEL Robox

The 3D Printer has a very refined, modern design, but it should also be mentioned that it looks much better in the photos than in reality. The casing and most parts are made of plastic, which makes Robox seem more like a traditional paper printer than a 3D printer. It is a very small and lightweight device, which is unfortunately reflected in the relatively build size. The 3D printer comes in a great packaging, with a number of extras and gadgets. It is the only device of its type, which in addition to a very solid pack of tools is equipped with a company jacket, a fleece jacket, and even a special material bag used for easy portability!

Technical specifications:

• build size: 21 x 15 x 10 cm
• number of printheads: 2 (only one prints at a time – more details below)
• printhead diameter: 0,3 and 0,8 mm
• filament type: PLA and ABS (dedicated)
• automatic recognition of the filament (only the original one, equipped with a chip)
• build plate: composite (material used in the production of PCB plates), heated
• self-leveling of the plate
• closed build chamber
• backlit build chamber, with changes of the color depending on the work mode
• communication: USB

The price for Poland is not known, however, it should be around 5500 PLN gross (999 £ – the price from the manufacturer website).

1. Getting started

Robox is a plug & print printer, so that even a completely inexperienced user should not have any problems activating it. One of its greatest advantages is the fantastic software – the proprietary AutoMaker, which literally takes you by the hand during calibration and the startup of the first printing. Installing the filament is extremely simple – push the roll into a special gripper on the left side of the device, and slide the tip of the plastic into the opening in the casing. When the sensor detects the filament, the engine that pulls it to the extruder and the printhead is switched on automatically.

The first plate calibration is quite long (it takes a good quarter of an hour), but it is very meticulous – in the course of the calibration for example the AutoMaker tells us to remove the build plate. Naturally, all this is done in accordance with consecutive instructions displayed by the software. The way the filament is changed from ABS to PLA and vice versa is another great solution. The 3D printer draws six horizontal lines on the entire width of the build plate thus clearing the head from the remains of the previous filament. The process is fully automatic and boils down to clicking the consecutive commands in AutoMaker.

When the filament is in place and the working table has been calibrated, we can proceed to printing. It is done in a very straightforward way: the AutoMaker consists of three independent screens – the 3D printer control panel, the 3D model editing panel, and the printing parameter settings panel, the printing launch is simply going through the three consecutive sections and a return to the beginning.

The sensor that prevents the start of printing with an open cover is a nice solution. As long as it is not closed, the printout will not start, and the software displays a message ordering its closure.

When printing starts, the plate and the head (or rather the heads) start to warm up. Before the printing commences, another interesting solution is activated – cleaning of the heads. The extruder moves up to a special cleaner, and both heads, consecutively spit out the filament. When it is separated it drops from the heads into a special opening between the working chamber and the underside of the casing. After the work is completed, you can open a special flap and spill the remnants of the filament out of the opening.

And that, unfortunately, are all the advantages of the 3D printer. When the 3D printing process itself starts, the problems start…

2. Working with the 3D printer

At first I printed with green ABS. Unfortunately, it hardly adhered to the plate, and even when it did, sooner or later it got detached. Without spreading glue on the plate, 3D printing with ABS on Robox is virtually impossible. Unfortunately, back then I did not know about Dimafix (it is hard to say if it was in Poland at all), and since the device was given only for testing I did not use ABS juice or BuildTak. Of course, there was nothing about the issue in the manual, nor did the producer provide any dedicated solution (DeeGreen of be3D at least had glue sticks…).

When I finally solved the matter of adhering prints to the plate, another problem appeared, which we are probably not able to solve… Robox has two printheads – one with a smaller diameter and the other with a bigger one. If you want to print in high or standard quality the model is printed with the head of 0.3 mm diameter, and for faster printing, in the “draft” option, the 0.8 mm printhead is used. The heads tilt, relative to the plate, by a few degrees – the head that is not printing is higher than the printing one. Unfortunately, for the majority of printouts it is too low still. With fast abrupt movements the head catches on fragments of the print and detaches it from the table. An obvious design flaw…

This problem is so prevalent that it suddenly turns out that some things just can not be printed – which we discover, unfortunately, usually after several minutes of printing.

The finals point of concern when printing with ABS was the typical model deformation. One of the prints I made was a fragment of Han Solo’s gun, which after printing got dramatically twisted, far from its original geometry or dimensions.

The way the models were sliced in AutoMaker proved to be another unpleasant surprise. Since the filament I had was green, I decided to print the figure of Hulk. After several hours of printing, when Robox started to print the hands it turned out that… the supports were not generated and it started to print the arms in the air…

After looking into the advanced settings I decided to switch the slicing engine from Cura to Slic3r, which ultimately solved the problem. Unfortunately, despite the fact that during the next three attempts the AutoMaker properly generated the supports for the hands, every time the problem with the second head hanging too low would recur. Every time, in exactly the same place, the printhead kept tearing the supports off the plate, along with the already printed fragments of the hands.

In fact, the only ABS prints which I managed to complete were: a shoe (unfortunately the 3D printer broke off the heel), a whistle (instead of the ball in the middle, which was detached from the substrate in the process of 3D printing, there was a shapeless roll of plastic), and a Batman bust (amazingly, this one came out quite good).

The change from ABS to PLA has substantially improved adhesion of the prints to the build plate, unfortunately, regarding the quality of prints themselves, not much has changed. Printing the famous Japanese fairy tale character, Totoro, demonstrated that Robox can not cope with finishing circular surfaces. The top of Totoro’s head (similar to the top of Batman’s head) was full of holes. The 3D printer could not cope with layering the paths. Interestingly, when browsing various websites depicting printouts made on Robox I noticed they had exactly the same problem. The thing that certainly should not be printed on this 3D printer is a sphere…

Another printout I realized – the Zortrax tiger, ended in pulling out the rear legs. The last thing I printed were the test models by Andreas Bastian from the MAKE magazine, but they came out so bad that I did not even bother to describe them. I can only write that I tried to print the fourth test (negative space tolerances) three times – each one was a failure. The other head tore the printout every time during the depositing of the first layers.

All the prints were made with the 0.3 mm head. I once turned on the “draft” option, when the printout was supposed to be made at high speed with the 0.8 mm head, but the printout almost immediately got detached from the plate, so I gave up altogether. I also did not try to print anything with the famous 0.02 mm layer. I decided that since Robox is not able to print an ordinary whistle, I would not waste my time trying to print with an accuracy of 20 microns.

3. Printout quality

Poor. The greatest success that can be achieved on Robox is that the printout was completed at all. As I wrote above – the 3D printer could not cope with closing of oval surfaces. The prints of the Hulk model were very promising – the feet and legs were printed in high accuracy, but it does not make much difference since I was never able to go any further than 1/3 of its height.

A dedicated ABS, printed in the default settings, in a closed build chamber, in which the temperature was over 60°C, got deformed as if it was printed on an ordinary RepRap in a drafty room. In the case of PLA these problems did not occur, nevertheless, the prints were damaged because one of the heads kept hitting them.

4. Software

The AutoMaker is by far the best aspect of Robox. The software stands out not only because of a fantastic layout but also because of great functionality and ease of use. Of all the programs I have had the opportunity to use – it most resembles a typical program for a regular paper printer. It is intuitive and guides the user step by step through all processes of the 3D printer’s operation.

When we put filament in, the color of the roll in the program is changed to the one that is actually on the roll. It informs us about the weight and the number of meters of the filament. When printing is in progress, we have a constant overview of the temperature of the head, the plate and the build chamber, and it is presented not only in the form of numerical values but also graphs.

Unfortunately, its downside is the problem, discussed above, with a random lack of supports’ generation when using Cura’s engine. You might say that, like with the 3D printer itself, as long as there is no relation to the printing process, everything is just exemplary.

5. Summary

CEL Robox is a fantastic 3D printer, which has only one significant flaw – does not print. It seems that its developers have focused on all aspects related to its operation, and omitted the issues that are most important in a 3D printer – related to actual printing of things. It is a very bizarre situation, because on the one hand Robox is almost an ideal device for everyone – both the home user and the professional, on the other hand it is suitable virtually for nothing… Although the 3D printer has been on the market for over a year (it was launched in mid-2014), it is difficult to find it even among the users at 3DHubs.

CEL Robox is the second 3D printer from Kickstarter which I had the opportunity to use (the first was Zortrax M200), and I regret to say that its creators have failed to meet the promises they offered during the campaign. In terms of functionality the device close to perfection – in terms of utility, it is a complete dud…