CEL Robox 3D Printer - Review

Table of contents

RoadTest: CEL Robox 3D Printer

Author: migration.user

Creation date:

Evaluation Type: Independent Products

Did you receive all parts the manufacturer stated would be included in the package?: True

What other parts do you consider comparable to this product?: At Leeds Hackspace we have a comparable 3d printer that is self-built according to the MendelMax design.

What were the biggest problems encountered?: The initial unit’s head jammed completely when attempting to print with a standard nylon filament, the parts variously do not stick to the bed and the print quality is variant even when printing the same models.

Detailed Review:

Headline of review

A respectable 3d printer but not one that “breaks the mould” as I was hoping.


Detailed review

The Robox is certainly a nice-looking printer that wouldn’t look out of place in a lot of SO/HO studios, and it has some very nice advancements over your average RepRap printer, so I’ll take a look at some of these first:

  • PEI Bed – this is an emerging default print bed, but one part that CEL are early to market with. It is certainly a good choice for this printer as it does make first layer adhesion, especially with PLA pretty neat.  I have with larger parts, and especially when plating up multiple parts however found it isn’t perfect, and requires regular cleaning (I use acetone when printing with ABS).
  • Dual nozzle – I wish this had been dual material, but unfortunately not.  The dual nozzle system does give the flexibility of printing fast or printing detailed, however I don’t find using both in the same print gives the results I would hope for.  Potentially more calibration is needed for the printer to know the nozzle distance.  The way the printer works also means you can’t use filaments that require a large nozzle* as it will always do a small purge at the start of the print with both, so the small nozzle would then clog.
    * Filaments such as LayWood, LayBrick, CopperFill etc.
  • Auto bed levelling – another emerging tactic of 3d printers and CEL being the first commercial FDM printer that I have seen implement it.  Unfortunately it doesn’t quite work, at least not all of the time.  Quite often the first layer will print fine down one side, go across the top and then get so thin it is not even visible on the other side.  This leads in most cases to difficulty removing the parts from the bed and the frustration when you snap the part before it releases is infuriating.
  • Heated build chamber with door lock – This one is both great and highly irritating all at the same time. I especially wanted a printer that could print ABS – so the heated build chamber was a must for larger parts.  Unfortunately when I first got the first printer, the door was locked and the “unlock door” function didn’t work at all, I had to take the printer apart somewhat to remove all the packing material!  Also, there does not seem to be any heater except the bed and hotend so the “ambient” temperature is whatever you get, and the definition programmed to the reels for what you want ambient to be appears to be ignored.
  • Smart reels – Okay, for me this is so much no.  Even given that the spools are reprogrammable, there is no conceivable benefit in my opinion to smart spools that isn’t massively outweighed by not being able to use standard filaments from standard suppliers.  I did manage to print with some cheap ABS I had about but winding it onto the empty CEL spool was tedious.
  • Print via SD – This is quite a nifty one, clearly the microcontroller is quite a powerful board on the printer as with the latest firmware, it transfers the g-code to the micro-SD card extremely quickly and whilst it’s transferring it starts printing.  Most reprap control boards you have to transfer the g-code to the card and transfer it separately as the comms is done via a limited speed serial link.  This has also allowed the printer to have a reprint last print option by “double pressing” the filament eject button
  • Eject Filament button – Handy if you want to switch filament without first going to the printer, I’m not sure about the default settings for this option, it seems to always set the hotend to 140c before ejecting, regardless of material in the spool.  For PLA that’s probably not too far off but for ABS, I’d be concerned.

So, that’s the main features that are unusual for a 3d printer to have, onto print quality:

The quality of prints from the Robox can be outstanding, the “fine” setting is really impressive, a lot due to the very fine lead screw that the printer uses to get very small layer heights.  Unfortunately the repeatability if fairly low, and delamination occurs even with the provided filaments.

(Delamination on dalek and failed layers on the cylon raider)

The overhang quality is relatively weak also and leads to sagging.  When printing technical parts like SD card slots that’s a really annoying thing to have to work around.

(Poor overhang on the dalek lights on PLA and even on the rings on ABS)

If the print doesn’t stick, it can lead to warping of the base, which I have experienced even with PLA. I know some neat tricks to get things to stick (dilute PVA glue for PLA and ABS dissolved in acetone for ABS) but then the prints stick too well and are more likely to break when removing them.

(warped base on PLA)

The printer’s Bowden-fed system also rules out some of the more interesting flexible filaments as they really don’t handle Bowden-feeding.  This is the case with a lot of smaller printers, reprap and commercial alike, as having a direct-drive system causes other issues that this printer avoids.

It was my intention to attempt printing with multiple materials on this printer, as I do with all my reprap experiments.  Unfortunately given the no serviceable parts nature of this printer, I have had to stick entirely to ABS and PLA.  My initial attempt to print with nylon caused the head to jam and the printer had to be returned.

Initially the bundled automaker software (which I had to redownload in full off the internet because it was “out of date”) used the Slic3r software which using it’s default settings wasn’t great, however in later updates, the software has switched to the Cura engine which is much nicer or at least is much nicer with the settings that come with it.

Talking of software… ugh. Closed-source software that uses 3d libraries in java that only work on Windows or Linux machines with nvidia cards? During my experiments, it appears it is just about possible to use something like pronterface directly but only a minimal set of g-code was accepted.  I run multiple printers from one machine and whilst tinkering on one of my others when the robox was printing from memory, I selected the wrong serial port.  When I sent a standard g-code to the robox by mistake, it stopped and wouldn’t talk to anything until I rebooted it.

Would I recommend a Robox to friends?

I’m not sure I would, no. CEL have made a valiant effort to make a “works out of the box” 3d printer, and I applaud them for their efforts, I really do, but FDM 3d printing is not in that zone yet.  If it were repeatable quality at its best settings, had better overhang performance (without support, that’s almost never the right solution), and didn’t delaminate, then maybe yeah as a “set it and forget it” printer it would be brilliant.  Until that kind of printer comes along, I’d stick with my firm belief that if you want a 3d printer, build it yourself because if you do, you know how it fits together, and when – not if, but when – it breaks, you have a much better chance of fixing it.

To end the review on an upbeat note, it did print the octopus in very nice detail in abs, which by coating it with graphite powder suspended in acetone to make the surface conductive, I was able to electroplate with copper :

(Copper-plated ABS Octopus)

  • It's worth noting that since this review, the printer has started skipping and jamming more.  I have the option of sending it back for repair (not certain if the warranty for a free printer would be honoured) or attempting maintenance that would definitely void the warranty.  I have also had others say they had the same problem and sent back the unit for a refund as they could not justify sending it back every time it starts skipping or jamming.  It's a real shame as when it works it's a lovely printer, but when it stops working you are completely without recourse except shipping back to the manufacturer for repair or refund.