UMMD: Migrating From Smoothieboard to Duet Ethernet, Part 1

Back when I started designing and building my own 3D printers about 6 years ago, Arduino/RAMPS was all there was to control a 3D printer.  Every configuration change required editing multiple source code files then recompiling the firmware.

About 4 years ago I switched from the 8 bit A/R setup to a 32 bit SmoothieBoard controller.  It was a huge improvement in usability, reliability, and ease of reconfiguring the machine.  There was no need to compile firmware- configuration changes were as easy as editing a single text file containing all variables, and rebooting the board.  I do a lot of experimentation in my printers with different extruders, different drive mechanisms, etc., so it's really been nice to be able to make changes quickly.  Motor driver chips were soldered to the board and adequately heatsinked, so there was no more blowing up crappy little motor driver modules.  Motor currents were set in the config file, so there was no trying to adjust microscopic, easily broken pots.

Every once in a while I try to repair a printer at the makerspace that uses an 8 bit controller and I am reminded how far things have come.  A recent extruder upgrade to a machine at the makerspace had me hunting for obsolete Arduino IDE, obsolete plugins, obsolete USB driver, and obsolete firmware, all so I could change the steps/mm in the extruder.  Ugh!

Duet controller boards came out a few years ago and have really come a long way, quickly.  Besides a lot of advanced programming, the newest boards use super quiet TMC motor driver chips, and favor networking over USB interface.

I've been unhappy with the way UMMDs electronics spoils the appearance of the machine from day one, but it was all working and rewiring a 3D printer is a major undertaking, so I've adopted an "if it ain't broke don't fix it" attitude.

UMMD's electronics, including an experimental remote print cooling blower (the sort of thing I need to be able to reconfigure for).  Ugly but functional.  The basket allows air flow and visual inspection of everything.

Another view.  The upper front cover panel slides down into the slots in the frame members, then the white top cover slides forward to seal the top edge and prevent the top front cover from opening.  It's useful at Maker Faires where curious fingers tend to push buttons and open things they shouldn't.

I haven't had enough motivation try out a Duet until Tony Lock at Think3DPrint3D sent me a Duet Ethernet controller board with a Panel Due 7i touch screen interface (Thank you very much!).  I just had more foot surgery and I'm stuck at home for the next three weeks, so I thought it's a great time to put the Duet into UMMD.

This will be the first in a series of blog posts on the conversion.

First impressions

The connectors on the Duet board are better than those on the SmoothieBoard.  They are designed for a little heavier gauge wire, they are polarized, and they snap into position and it takes some effort to dislodge them.  The board also came with crimp ferrules for use on wires going into the screw terminals.  Nice!  The main power input and bed heater connections are super beefy screw terminals.

One of the things I liked about the SmoothieBoard over the Arduino/RAMPS set up I started with about 6 years ago was that all the connectors were brought out to the edges of the board.  That made it much easier to lay out the wires and cool the circuit board.  The Duet has so many connectors, including a wide expansion header, there isn't room for all of them at the edges of the board.  The ability to expand the electronics is probably worth the extra clutter when all the cables are in place.

The SmoothieBoard has always had small and oddly placed mounting holes with little clearance from adjacent components, making it a little tricky to mount the board.  The Duet and Panel Due boards both have regular hole spacing and plenty of clearance around the holes for screw heads and standoffs.  One of the first things I did was locate a CAD model of the Duet board so I could plan the enclosure.  There was no Panel Due 7i CAD model to be found, so I made my own in Fusion360.

The Duet board has motor drivers that interpolate the 16:1 ustepping to 256:1 to make the motors run quietly.  I'm looking forward to that, and will post "before" and "after" videos of UMMD running under smoothie drive and Duet.

The Panel Due is a huge improvement over the LCD module I've been using for the SmoothieBoard.  It has much more control capability, however, the uSD card slot is located along the bottom edge of the board which may make it difficult to use.  Also, it doesn't play well with the PT100 daughterboard in case you use one of those (and I plan to).  The designers really put the emphasis on network control and I may have to start using it whether I like it or not.

Next post: Firmware updates and configuring