3D Printing (Part 5)

Part 1234567891011

Makerbot Replicator 2x review!

Our printer totalizes about 250 hours of printing, so as to say almost 2 kg of ABS filament thawn and printed with an average printing time of 1.5 hour.

The Replicator 2x is as it looks: strong construction, simple and clean design, made for printing quite large batches of parts. While the mechatronics and electronics are out of question in terms of reliability, some critical parts are of poor quality and have a strong impact on printing quality and ultimately will create disappointing global failures.

The major discrepancy that I faced was related to thermocouples. Although they look fine, they are not fit for purpose. Firstly, the manufacturing quality is poor, as the wires at the tip are simply twisted and hopefully spot welded. This is not sufficient. Extruders exhibit frequent and large temperature swings (from ambient to 220 deg C and more). These temperature changes are stressing the thermocouple in such an extent that they will fail after only 100 hours of operation. Real thermocouple are not only spot welded but a small bead will insure a good mechanical behavior. The threaded termination looks alright, but it generates some complexity when dismounting the thermocouple. Not to talk about the Kapton tape insulation which is not really necessary and will unwrap easily. The thermocouple wire path should be improved in order to prevent these bends in the extruders area.

859822304-40

Ultimately, my plan is to replace the actual thermocouples by a simple model which is specified -75 to 250°C, 1 m  in length, twin twisted cable of 0.2mm insulated with PTFE . The idea is to use the thread of the actual design for inserting a locking screw which will keep the thermocouple tip in close contact with the extruder body.

42261516

Fans! They are NOISY, they may even make more NOISE before failing. And they are just enough in terms of cooling efficiency. I replaced them for PAPST model which are more expensive but proved to be quiet and very efficient (Confirmed by checking the temperature of the unused extruder).

Ultimately, the ribbon cables for the X axis control require a better quality and/or guidance in order to prevent wire from being cut.

All three thermocouples, fan and ribbon cable failures have been responsible for degraded printing quality over the time and thus loss of time and consumables. Cheap parts make expensive prints after all!

The cover is an enigma to me. It seemed to me that printing quality would benefit from a closed cabinet. This is true and false. This is true as long as the part is small (short printing time) and room temperature is pretty low. Otherwise, the temperature inside the cabinet gets so hot that the ABS will prematurely melt, leading to filament jam and plenty cleaning time ahead. Better results have been achieved after tilting the top cover by few degrees and half opening the front cover in order to create a gentle natural stream of air. So what?This system misses a thermal regulation of the internal temperature.

Now that I fixed these issues, the printer is working really well. In other words, the chances that a part is successfully printed are almost 100%, leading to a high printing efficiency and low loss of consumables and repair time. You lay also check this thread for improving the success rate.

Wish list:

  • While the lighting of the Replicator is real fun, it fails putting light at the most critical place: extruder nozzle and printing surface. This would cost a pair of wires and a white LED. Big deal?
  • Bleeding nozzles may be responsible for printing failure. Fortunately, you will quickly see that the printed trace made by one extruder is degraded by the other nozzle! Having a brass brush over which the printing head would perform a  couple of back and forths would be great. This actually not my idea but something I saw on a Stratasys printer. It should no longer be a problem to reuse this idea, in case it is patented!
  • The navigation pad in front of the printer is nice but many false commands occur due to its high sensitivity and to the lack of sensing of the triggering point.

HTH

 Next post on same subject

Leave a Reply

You must be logged in to post a comment.