Another Stratasys uPrint retrofit



  • I am slowly working my way through replacing a uPrint trajectory control board with a Duet3D.

    I am doing this partly to help my uni but mainly for my sanity (I needed an integration challenge)

    Primary constraints were to make no permanent modifications to the printer and to be able to return the machine to factory functionality. Primary goal was to reduce operating costs and retain a reliable ABS capability. I intend to make the files available once I have an acceptable level of functionality. There has to be a stack of these machines tucked away in corners gather dust, just waiting for a new lease on life. Fully appreciate the build volume is tiny for the footprint but reliable, economical ABS printing has its uses.

    As I am working on this part time, updates will be sporadic, but they will come. Financially the project is too far along to just walk away from it. Besides, professional pride won't let me walk away anyway 🙂

    Currently I can read cabinet and hotend thermocouples. These aren't calibrated yet but they do move in the right direction.

    I can control the cabinet and both hotends individually and each will maintain a set (uncalibrated) temperature.

    I can move the X/Y gantry and Z platform in the correct sense and roughly correct distances. Many thanks to the work done by drphil3d on steps/mm here; https://forum.duet3d.com/topic/10982/stratasys-uprint-retrofit-finally-complete

    X/Y endstops work, so X/Y homing works reliably.

    Top few items on a very long TODO list;
    Z probe, leading to full homing and mesh bed levelling
    Thermocouple calibration
    Rebuild the blocked hotend (that's how I received the printer)
    Start figuring out the extruder drive.


  • administrators

    Sounds good!

    Thermocouples connected to the Duet TC daughter board don't require calibration. All you need to do is make sure that the correct thermocouple type is configured. If you select the wrong type of thermocouple, the room temperature reading will be correct but higher or lower temperatures won't be. K type thermocouples are the most common



  • I appreciate the input. It isn't as simple as a direct TC connection.

    The printer chassis has signal conditioning for the TC's that should be outputting 10mV/ degree C. Given the rest of the logic is 5V based, I've run the conditioned signal through a voltage divider to drop the full scale signal down to 3V3.

    When I power the hotends, it takes 25 seconds before there is any change in indicated temperature. When I heat the cabinet (only), the hotend temperature stays fixed. This leads me to believe there is a minimum temperature before the factory signal conditioning starts to react, but I'm not sure what that point is.

    Luckily the wiring uses standard TC connectors, so once I track down a thermometer that takes the connection, I should be able to work out the cal factors.



  • Hi There Pete_A

    We are in a similar position to you, also at a University. We are looking to get a Stratasys Dimension Elite going. You are a bit more advanced than us, we might end up stripping quite a bit out including the hot end and extruder. I will be very interested to see how you get on.

    All the best, Thommo1tigers



  • The gantry hardware and hotend/extruder looks to be identical between machines apart from build volume. I can see a lot of similarities between the power distribution board and the trajectory control board. I suspect the same core design team worked on both, so it wouldn't surprise me if the interconnects are the same pinouts.

    Part of the machines capability comes directly from the tilting hotend design; If you are planning to use separate support material then I'd have serious think about making the factory hotend work.


  • administrators

    As far as I know the factory extruders on the DE use DC motors not steppers (even open loop ?) Is that the same in the uprint?



  • @T3P3Tony Correct.

    Driving the servo motor was one of my high risk items to solve. I'm planning to use step/direction from the Duex connector and glue logic from JRKerr https://www.jrkerr.com/icproducts.html#PICSERVO

    The head uses a single motor to drive both tools. Changing tools requires a specific set of X/Y motion that tils the head and brings the required hotend into vertical orientation. This action also causes the required filament to be pinched against the extruder drive. As a bonus, the inactive hotend gains a few mm clearance from the print bed.

    The toolchange actions are 'just' a gcode macro but I'm confident I can work that out. My concerns are ; How will the firmware handle E2 / E3 commands as using the same step/direction outputs but reversing the direction for the alternate extruder gcode commands.
    And interfacing the the chassis H-Bridge hardware.


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