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Sunday, May 25, 2014

QU-BD Revolution XL Review Part 4

After a bit of a hiatus from blogging, I decided to return with this final review of the QU-BD Revolution XL that was delivered to me in August of 2013.  At this point it is no longer operational, pending some necessary upgrades.  Before I launch into the full list of problems and design flaws of the RXL, it is only fair that I give mention to its positive attributes, chief among them - build quality.  It's frame is well-engineered, its rods are well-polished and it was obvious that QU-BD set out to make a world class 3D printer.  That said, here were the problems that plagued it and more that eventually turned it into a very heavy paperweight:


  • Loose Bed:  The volcanic glass bed does not fit snugly on the tray holding it.  There is about a 2mm gap in both directions.  If you are printing slowly enough to limit vibration, this issue is of no consequence because of the weight of the bed but if you step up the speed (the RXL was arguably built for speed), vibrations will move the bed slightly mid-print, resulting in a failed print.
  • Z-axis homing: Within a couple of weeks of use, Z-axis homing repeatability became a problem and the problem increased from there.  A couple of factors were to blame:  the position and quality of the Z-axis endstop.  The problem with its position is that it was located on the side of the unit whereas the Z-axis leadscrews were toward the center.  Fellow RXL owner Illuminarti came up with and posted an inventive solution to this problem, which I have adopted.  The second problem, that of the quality of the switch itself came close to causing the machine to damage itself.  The switch would remain in the opened position despite being pushed all the way in.  Fortunately, my unit unlike those of others who had this problem, was never damaged.
  • X-truder: This was supposed to be one of the big selling points of the RXL.  It is a small extruder with counter-rotating gears that is still advertised by them as "the best extruder on the market".  After 9 months with it, I would beg to differ.  My first one began to fail a couple of months after I received the printer.  At one point it decided to stop extruding and to instead start clicking.  QU-BD was good about getting me a replacement and asking me for the return of my old one for analysis but claimed to have solved the problem.  A few months later the same problem occurred again, but the second time would bring me no customer service solution -- but more on QU-BD's customer service later.

    One of the big consequence of the X-truder's compact size was that the cold barrel leading to the hot-end had no cooling fins.  This was fine if you wanted to print a vase or other parts not requiring retraction but anything but the slightest of retraction would inevitably lead to a clogged nozzle.

    The biggest problem with the X-truder was that the tension of the gears could not be adjusted.  Practically speaking, this meant that I could never get it to extrude Taulman's T-Glase, one of the more popular filaments, because the gears would slip against that filament's smooth surface.  I could get smooth PLA to print but only at painfully slow speeds.

    In the end, I, like others, had to resort to third party extruder/hot end replacements.  I will detail my upgrade process in a future post.
  • Extruder carriage nanolinks:  I can see why QU-BD thought the use of Nanolinks cable management for managing the wires going to the extruder and hot end was a good idea.  It did keep things looking clean.  The flaw was that the carriage moves back and forth so quickly that the nanolinks' restriction of the motion of the cables to one direction would inevitably result in metal fatigue occurring in the heater wires.  This has happened to several RXL users, myself included.  This was in fact the flaw that finally silenced my RXL.
The biggest flaw with the RXL lies not as much with the printer itself but with QU-BD's customer service.  Recently, they changed their domain name/company name from QU-BD.com to QuintessencialUniversalBuildingDevice.com.  I suspect that this move was one way to deal with the online customer backlash that Googling "QU-BD" will reveal.  There is nothing like re-branding!  Unfortunately, the new multi-syllabic name does nothing to address their festering customer service problems.  As an example, I opened a case with them the moment when my extruder and cable failed.  Their rep wrote back to me within 10 days, telling me that they would send me a new improved extruder that had been improved upon.  That was 4/6/14.  On 4/15, I sent a message asking if it had in fact gone out.  Nothing.  On 4/28, I wrote again.  The rep did get back to me that day and said "Sorry for the delay. We ran out of the extruder stepper motors but just got a new batch in. I will make sure that it goes out today."

That was one month ago.  Still nothing.  My subsequent inquiry on 5/8 resulted in no reply.  I give up.

An upgrade of the extruder/hot-end to a modern, all metal design will likely put many of these issues to rest and result in a greatly improved printer.  I have chosen to go with a Bowden version of this high-quality extruder/hot-end pair from Micron3dp.  When I am finished upgrading the RXL, it will no longer be the same machine.  I will make it work and and I have no doubt it will be greatly improved, but in retrospect, I wish that I had simply bought an Ultimaker.  Had I done so, more of my writing would have been 3D printer use rather than 3D printer fixing.