Here is my upgrade history and some thoughts on using the Monoprice Ultimate after a year nonstop use.
All the great designs and collaborations on Thingiverse made it possible to get this printer to work for PETG, Carbon fiber PETG, ABS PLA, TPE, Ninjaflex, Ninjatech, Cheetah, Nylon etc. After these upgrades the printer is working great and is producing high quailty prints at speeds of 30-120 mm/s depending on the filament.
Further details can be found in the descriptions of the things and remixes I posted for now and I will eventually integrate that info here.
I bought the printer shortly after it was reviewed by hackaday.com and I knew I would be getting basically a 24V based clone/parts collection with little quality control for cheap.
Many screws were loose like the endstops. Most critical screwup were the screws holding the heat plate onto the build plate that were creating shorts to the cooper leads in the heat plate resulting in spectacular sparking. Easily fixed with some teflon washers.
Critically for print quality is to fasten the screws for the z guide in the back of the print bed or you will get z banding in the print.
1) Filament Cooling. The original shroud is useless and even directs the airflow away from the nozzle down onto the heat bed. Used a double fan shroud for a few months but it created a lot of vibration (as did the fan on the cooling block) and the airstream wasn’t very directed and uneven cooling of the print resulted in splitting and warping of particularly ABS. Tested many shrouds that worked already great and remixed them to get something that worked for me integrating a proximity probe. There are many continuous efforts to improve this further.
2) Hotend. Switching between PLA and ABS led to deposits restricting extrusion that had to be cleaned out every view prints. Trying to print PETG required temperature up to 250C but during longer prints the filament would get soft further up in the extruder restricting filament feed. Solution was the upgrade to Micro-swiss hotend.
3) Silicone boot. Stabilizes the temperature particularly if you increase the airflow from custom shrouds and prevents heater errors. Also decreases required temperature setting by 5-20C depending on the filament. This tells you how much heat is lost here before it reaches the nozzle. Further, the extruder above the heat block stays much cooler and environmental temperatures don’t impact the print anymore. Indispensable upgrade for me as it doubled my print speeds for all filaments and allows for high cooling air flows where needed, particularly PLA.
4) Flexible filaments. This required a new drive block and a gear with sharp teeth to prevent slipping and to enable much better retraction. There are commercial upgrades that should work great but I didn’t feel like spending the money on that for occasional flexible filament printing.
5) 1mm PEI print surface. Fantastic addition for me. PETG 70-80C PLA 70C ABS 100C bed temperature for best adhesion. At 40-50C the prints can be easily removed. Sometimes you need to heat up again to that temperature range. Easily maintained by occasional wet sanding with 1000 grid sand paper.
5) Auto bed leveling. A big relief and no fusing around with bed leveling anymore. Perfect leveling and PEI allowed me to get rid of rafts for good.
6) Marlin for duplicator 6 firmware. Much better compared to the original Wanhao Ultimaker firmware copy. Switched primarily to get auto leveling but it allows so much better control of the critical parameters. My original firmware also was crashing constantly although prints always finished nevertheless.
7) Filament end detection. Marlin also allowed me to integrate an end detection switch. When the filament runs out the printer stops and you can add new filament and continue printing were it left off automatically.
8) Noise damper. I made new more solid brackets to support damper and X and Y steppers. The silence when printing is unbelievable and keeps the family happy. Also printing at high speed doesn’t create the scary racket anymore that seems to suggest the printer might fall apart. PLA at 90-120 mm/sec is no problem anymore, although I only use that higher speed for prototypes. Prints have improved as well without the vibrations in the system.
9) Filament spool with bearings. Particularly with flexible filaments I noticed that there can be quite some tension when pulling in the filament. I didn’t notice any shaving of filament at the extruder gear since installing one.
10) Enclosure. Made my own enclosure from home depot from 2-3 mm lexan sheets for sides and door and ¼ inch plexi for the top, which has a wide opening in the back so not to pinch on the cables. Mostly to keep the cats and dust out I guess. I never print with the top on as the hot air inside will decrease cooling were it is needed.
11) Cooling block fan and motherboard cooling. Changed the fan on the cooling block to something that is much more efficient and doesn’t create vibrations. Added an efficient blower to cool the Ardunio board. The fan that was supposed to do that wasn’t even plugged in when the printer arrived, was horrendously loud and positioned to be ineffective. A symptom for not enough MB cooling are sudden xy jumps. Found out when my fan was clogged up with dust and not spinning. Have now two fans cooling the MB.
12) Simplify 3D. The dense support feature, changing printing parameters at different layer heights and automated extrusion control for small parts makes it worthwhile the price.
13) 4x4x1 cm heat sinks on top of the x and y steppers. At high printing speeds the stepper get rather hot. I hope this will keep them alive.
14) Webcam/Gopro mount attached to the bed for time-lapse photography.
15) Octoprint running on a PI so I don't have to swap the SD card anymore and for time-lapse. Smaller objects I directly print form simplify3D but that is risky for long prints as crashes or some programs can disrupt usb connections and that is the end of the print. When printing through octoprint the filament run out switch can be run to the Pi. However, I recommend using the board connection and enable Board Mode in the Filament Sensor Reloaded plugin. Works like a charm. If you connect through the PI pins you have to edit the configs as M600 will get you into a repetitive loop and the print will not resume. If someone has figured out a good gcode script for the D6 to us the Pi pins please post.
16) Bridged the blue relay on the motherboard. I finally had to do this as the relay started to stick and no fans would come on when switching the printer on. Bed/nozzle heating wasn't working either. Apparently newer printers already have this bridge installed as the relay can fail and heat up to the point of visual burn and melting. The purpose would be to prevent power spikes from the power supply reaching the mother board but all seems to work fine without it. Hopefully until I find a replacement.
17) Steel nozzles. Using these as I print a fair amount of carbon fiber PETG. I find that I have to turn up the temperature by 3-5C.
18) Heat element/cartridge in the hot end will have to be replaced eventually. These are 24V 60W. At least the one that came with the printer and one replacement from Wanhao. Be careful that you don't order from a place that doesn't give you the specs. No excuse as this is printed on the elements. Be aware of specials. I had one that was advertised as for the Wanhao D6 but was only 40W. This resulted in much longer time periods to compensate for temperature drops when the cooling blower switched on and stalled prints with heater errors. One could compensate in firmware for the longer heating/response times but I also got heater errors when printing fast and the heat element couldn't keep up. I stick with 60W.
19) The Z axis stepper motor was only attached with 2 of the 4 screws probable because the ones in the back are difficult to reach. When the printer arrived the motor was tilted slightly and straightening everything and adding the two missing screws got rid of the remaining z banding I had in faster prints. Also the Z movement is so much quieter now that I didn't bother installing a noise damper on the Z.
20) The extruder cable finally broke. The extruder stepper was just oscillating forward and backward. Closer inspection revealed a break in the cable close to the extruder. Fortunately I could cut this part off and press the crimp connector back in place. Works fine again but I guess it is time to get a replacement cable. 1.5m, 16 lead ribbon cable, 1.25 mm Pitch, $6 on amazon.
21) Finally decided to feed the filament from above and made a new extension for that. Should have done this a long time ago so much more convenient and no problems with rough filaments anymore.
22) Exchanged the PEI bed with a Wham Bam system with a magentic base, steel flexi plate and PEX surface. Very nice and the proximity sensor loves the steel plate, detects it at 1cm distance.