TEVO Little Monster Duet Ethernet Conversion



  • Hey everyone. I just wanted to share my success story of converting a TEVO Little Monster delta 3D printer (350mm x 500mm printing dimensions).

    Initially, the LM comes with a knock off E3D Volcano (.4mm nozzle), a knock off E3D Titan flying extruder, and a knock off Smoothieboard called the MKS SBASE that also includes a 3.5" touchscreen LCD. I ended up ditching all of these parts in favor of genuine E3D parts, a .6mm nozzle, a Duet Ethernet controller, and a 7" PanelDue:

    Prior to the upgrades, there were MANY little issues plaguing the ability to have a reliable 3D printer. First and foremost, after I purchased the printer, TEVO made the following announcement on the Facebook TEVO Little Monster Users Group:

    Huh? So the printer I bought that advertised the ability to use a network connection to control it has the company no longer recommending we use it over that network connection? According to TEVO, the ethernet connection causes the MKS SBASE controller to become unstable, so it's now not recommended to use the ethernet connection for anything.

    Next up is the fact that the LCD monitor has a horrible layout of information. The ability to display error messages? No can do. When the MKS SBASE encounters a runaway thermal event (e.g. when you have a strong fan blowing on the hot end and it drops the temp below the thermal watchdog threshold) the board stops completely dead and becomes completely unresponsive to your command inputs coming from the LCD.

    Another issue I was not expecting is that the 32x microstepping from the DRV8825 stepper drivers on the MKS SBASE coupled with 1.8 degree stepper motors, AND a large format printer with nearly a 400mm effector arm length result in some pretty interesting ringing/texturing of parts. The 256x microstepping of the Duet Ethernet was a huge influence on going this route so that I could smooth out the surface of my prints.

    Lastly, with stock Simplify3D settings, I was getting absolute crap for prints. Literally every print was inconsistent quality. I was getting a completely different print even if I immediately re-printed the same g-code. After doing this conversion, I've now concluded that I seem to have been provided with a defective MKS SBASE controller board. Given the amount of oddball issues I'm seeing on the Facebook TEVO Little Monster Users Group, I'm beginning to think there's quite a few people out there was defective controllers. On the Facebook group, you either have people posting absolutely beautiful prints coming off of their Little Monsters or you have frustration posts with people who are having an extremely difficult time printing the simplest of objects such as a 20mm calibration cube.

    The conversion itself was pretty simple! I ended up drilling/tapping three out of four new holes for mounting the Duet Ethernet controller:

    After that, the worst part was definitely getting the pins for the connectors installed. My 2.54mm pin crimper unexpectedly ended up snapping off the supportive tabs that hold the wire insulation, so I resorted to manually crimping each pin and then lightly soldering each crimp for better conductivity.

    Once mounted and wired, the PanelDue was installed in this Thingiverse object (the 15mm model):

    https://www.thingiverse.com/thing:1992124

    Thingiverse object "LPA_TFT28BoxV3_FootM5" was also printed to create a strong mounting point for the PanelDue to attach to on the TEVO Little Monster:

    https://www.thingiverse.com/thing:2132557

    To mate the two together, I modeled up a back cover for the PanelDue case:

    Once printed, cleaned up, and installed, this is the end result:

    After taking a brief amount of time deciphering all of the suggestions in the BL Touch thread on this forum, I had the Duet Ethernet up and running very quickly. After making the change to a .6mm nozzle and enabling auto extrusion width in Simplify3D, here's literally the 3rd print off of the printer since completing the conversion:

    The vase itself is over 450mm tall and looks absolutely beautiful!! I am beyond impressed with the Duet Ethernet controller and how simple the conversion was.

    Here's the full instructions and 3d models for doing the conversion (along with the mount and case for a 7" PanelDue):

    https://www.thingiverse.com/thing:2355136

    Thank you to everyone on this forum who has been so forthcoming with information (especially all of the juicy tid bits in the BL Touch thread). Without it, I wouldn't have been able to do this conversion as easily as I did!!


  • administrators

    Thanks for telling us! I'm glad it worked well for you. From your experience, is there anything you think we should add to the info on connecting a BLTouch at https://duet3d.com/wiki/Connecting_a_Z_probe#BLTouch ?



  • Would you mind sharing the files for that back Cover please.

    Doug

    Sorry having re-read your post properly I see you've said you are going to!! Doh my Bad


  • administrators

    Thanks for the comprehensive write up. once you have put the information on thingiverse I will link this and the thingivers stuff from the tutorial page.



  • Your timing couldn't have been better as I'm in the process of configuring the same board for the same printer.

    Any ETA on releasing your configuration?

    P.s. I think what TEVO meant with the ethernet printing not being "stable" is the usual problem of the crippled SD card bus bottlenecking transfer speed on the board (in the manual they also recommend against USB printing).



  • I'm also eager to see the details on this after pulling my hair out of pure frustration over the original controller.. There wouldn't be any show stoppers in regards to only switching the controller, but keeping the original extruder and volcano?



  • @kenavn:

    There wouldn't be any show stoppers in regards to only switching the controller, but keeping the original extruder and volcano?

    The only incompatibility I've thought of is that I believe that the stock optical endstops use 5V, while Duet WiFi/Ethernet expects them to run on 3.3V.

    Hopefully somebody who knows more can chime in on this.

    (it's probably not a big deal to take 5V from GPIO or something, in any case)


  • administrators

    It's usually possible to convert 5V optical endstops to 3.3V. Identify the resistor in series with the IR emitter in the slotted opto switch and reduce its value by about 50%. If it's a surface mount resistor and you don't have SMD desoldering equipment then it's easiest to solder a second resistor of equal value on top of the existing one.



  • I find a lot of optical endstops will work on 3.3v but to get a positive trigger you need large, black optoflags to trigger them, anything less doesn't give a solid trigger.



  • My Tevo LM will be here next week. It would be nice to use these components to start with on the initial build up.
    Should would be sweet to see that posting of full instructions to Thingiverse go up soon or did I miss it?

    Better go look again!
    πŸ™‚



  • @inachisiojexus:

    @kenavn:

    There wouldn't be any show stoppers in regards to only switching the controller, but keeping the original extruder and volcano?

    The only incompatibility I've thought of is that I believe that the stock optical endstops use 5V, while Duet WiFi/Ethernet expects them to run on 3.3V.

    Hopefully somebody who knows more can chime in on this.

    (it's probably not a big deal to take 5V from GPIO or something, in any case)

    I thought of this as well, but thankfully, it appears the stock optical endstops are working just fine on 3.3 volts. Homing is working perfectly without further modification.



  • Sorry for taking so long to post this, but here's the complete conversion instructions and 3d models for the conversion:

    https://www.thingiverse.com/thing:2355136


  • administrators

    Awesome! I have added a link on the wiki to this thread and the thingiverse entry. Thanks for taking the time to document this.

    https://duet3d.com/wiki/Tutorials#Setup



  • Thank you! πŸ™‚



  • Are you happy with the dimmensionall accurancy of the printer? I have a spare Duet wifi and im dreaming of a delta Even if i got parts for a big Core xy on MGN rails on the bench ^^ Delta's Looks so cool!



  • @minim:

    Are you happy with the dimmensionall accurancy of the printer? I have a spare Duet wifi and im dreaming of a delta Even if i got parts for a big Core xy on MGN rails on the bench ^^ Delta's Looks so cool!

    I am. I've been comparing the setup to my SeeMeCNC Rostock MAX V2, which has been my bulletproof printer that cranks out my my accurate prints. So far, the TEVO with a Duet is within a 15-20 microns. Not bad for something I haven't tweaked at all compared to the Rostock that I've spent a significant amount of time dialing in over the past year.



  • Seems I just have to get one πŸ˜„ Thanks for the info Emulsifide!



  • I can at least confirm that the frame seems very rigid, which alongside the large print volume was the main selling point for me.

    I guess I was lucky with the controller too because I did get fairly consistent print quality with it. That said, it does crash occasionally mid-print but there's a chance you can resume the print if you don't go back to main menu and instead just turn the power off and on again. And when I say "consistent" I also mean that it seemed to produce unwanted print artifacts consistently too…

    I'm pretty sure temperature sensing was off too.



  • Thanks again for sharing this.

    I've received my Duet Ethernet, and I am actually also waiting for some .9 steppers for the XYZ. I am a bit unsure though, on the necessity of replacing the stock 1.8 motors.. Will this actually be worth the hazzle? As I understand from the Duet documentation, the .9 ones are recommended to increase the torque on micro stepping these axes on deltas, but is there a strict need for it on the LM? Will a replacement actually give me better results down the line compared to the stock ones? (3d-hw-mod-newbie-alert)


  • administrators

    Using 0.9deg motors reduces the fine moire you get on prints from a delta. You can see my findings at https://miscsolutions.wordpress.com/2015/08/01/upgrading-the-large-delta-printer.


 

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