SoM Gets a Duet WiFi and PanelDue 5i Controller

A few months ago, the SmoothieBoard in SoM died when I managed to short something while working on the printer, so we installed an MKS Sbase board that one of the MakerSpace members had handy and also runs SmoothieWare.  Unfortunately, it was a piece of crap and didn't reliably read SD cards, and more recently, jogging the Z axis also moved the Y axis for some reason.  It had crappy DRV8825 drivers, too, that I never liked.

I decided to do the only sensible thing and install a Duet board, and since I had experience with the Ethernet version, I decided to try the WiFi board with a PanelDue 5i interface.

My experience with the Duet Ethernet board in UMMD has been mixed.  It has been very reliable, the drivers are really quiet, I like the Panel Due interface.  But I prefer to run printers from SD cards for reliability and not having to connect a computer to the printer.  The Panel Due 7i has a uSD slot along its bottom edge.  Unfortunately, the way the panel is installed in UMMD, I can't readily access the card slot and even if I could, it's a little too far from the controller board (you need to use a short ribbon cable to make the connection).  The Panel Due has the option of rotating the screen 180 degrees, so I could theoretically flip it over and make a hole in the top of the printer to access the uSD card slot, but then I'd have to worry about things falling into the slot and jamming it up.  Even though I have relatively small fingers, and mad hand skillz, handling a uSD card is a lot more difficult than an SD card.  I'm looking into fixes for that - maybe an outboard SD card slot that will plug directly into the Duet board.  With the Ethernet board and Panel Due 7i I found that I needed to keep a computer connected to the printer just to load gcode files.  That feels like a backward step to the bad old days when I was using Arduino/RAMPS and Pronterface to control the printer.  At least it uses a reliable network interface instead of USB with flaky drivers.

Sure, a Duet WiFi controller board would eliminate the need to have the computer physically connected, but if I take the machine to a MakerFaire or other location, I won't always have a reliable wifi connection to use, and I don't like having to waste time debugging flaky wireless connections.

I tested the Duet WiFi in the sand table before I installed it in SoM.  In the sand table the wifi controller is especially nice- I don't have to have any controls on the table which means I don't have to try to hide them.  I have ordered a Duet WiFi board for the sand table and will write a post on that when I get it installed.

Networking a 3D Printer?

Call me a Luddite, but I really don't see a big advantage to having a 3D printer on a network.  I clean the bed and verify that the filament spool that's loaded has enough filament to finish the job before every print.  If I have to go to the machine anyway, why not just plug in a card and start the print while I'm standing there?  The Duet's web server provides some data and control that is still missing from the Panel Due, but a lot of the data isn't particularly useful to me. The missing control capability in Panel Due can easily be added via macros, and I'm hoping that one day the Panel Due firmware will catch up to RepRap Firmware that runs on the Duet board.

Some people go out of their way to add a RPi running octoprint to network their printers.  If I were a baseball fan, I'd probably like staring at my printer while it's printing and enjoy the enormous amount of "stats" octoprint can produce, but I have better things to do I'm not impressed or entertained by data that isn't particularly useful, so I don't care too much for either baseball or octoprint.  I have no desire to try to impress people by starting prints using my phone, though it might be handy to be able to stop them when they fail (pretty rare).  It makes no sense to me to do the slicing on an RPi when I use CAD to design the parts I print on a higher powered, much faster laptop.  Maybe slicing on an RPi is OK for people who just download stl files to print, but I don't know many 3D printing people who remain at that stage for very long.  Sooner or later, almost everyone who gets into 3D printing wants to print their own designs.

Panel Due 5i Enclosure

I decided to try the Duet Wifi board to replace the controller in SoM.  Who knows, maybe I'll be impressed enough to change my mind about using SD cards and wireless networking.  But just in case I don't, I designed and printed an enclosure for the Panel Due 5i that leaves the uSD card slot accessible.  In SoM the Panel Due is close enough to the Duet board that the uSD ribbon cable works, so I have the option of using either the wireless network or the uSD slot to transfer gcode files to the printer.

The enclosure design was based on a GrabCAD model of the Panel Due 5i board.  Kudos to whoever uploaded the Panel Due 5i model because to my pleasant surprise, it was very accurate and my enclosure fit on the first attempt.  Even with the accurate model, I managed to spend far too much time designing the box.

This box was designed to allow easy access to the uSD card slot.

The top of the box has labels for the erase and reset switches that are used when updating the Panel Due's firmware.

The bottom of the box has holes for mounting it on a panel (I'll probably just use velcro tape) and slots that allow the ribbon cable and 4-wire cable (not shown) to pass through the wall of the box.

The circuit board is mounted on the top cover using 4 small plastic anchor screws.  The top cover snaps onto the bottom cover and holds securely.  The bottom cover has bosses that provide mechanical support for the top cover and circuit board.  I have since updated the bottom cover design to include some webbing to give it more rigidity.

The enclosure prints in 2 pieces without any support material.  The board screws to the top cover using 4 small screws, and the two halves snap tightly together and can be pulled apart as needed to access the the board for firmware updates, etc.  The Fusion360 CAD file is here.  It includes the GrabCAD model of the Panel Due 5i.

Installation

Before doing anything else, I updated the firmware in the Panel Due and added my own splash screen.  I used Irfanview to put red text on a green background (to match the color of the box), cropped it to 800 x 480, saved it as a .bmp file, compressed the .bmp file with escher3d.exe, then added it it to the firmware file using a "copy" command per the instructions, here.

I went through the cables in the printer and labeled them (probably should have done that years ago) as I pulled them off the MKS board so they'd be easy to identify and connect to the Duet board.  I replaced a bunch of the connectors with the much better quality ones that came with the Duet board.

I mounted the Duet board in the printer's electronics drawer on of the board mounts I designed and printed for UMMD.

Configuring the Duet Board

I used the online configurator and checked it against UMMD's config file to try to minimize problems.  I mounted the board and started hooking up the various connections, testing them as I went along to make sure they were working right and tweaking the config files as necessary.  It took about an hour getting everything working right, so it was pretty easy.

SoM had a DSP based driver and 32V power supply for the Y axis motor that was used back when it had a ball screw drive.  I did a couple experiments and found that the driver on the Duet board could deliver sufficient current to drive that motor, so I took out the DSP driver and power supply.  Simplification!

I ran into one problem after installing the Duet.  The X axis was making a lot of noise and vibrating.  Maybe it had been doing it for a long time and the noise was masked by the noisy ball screw that used to drive the Y axis.  I didn't pay much attention to it when I put the MKS board in the machine- that was a temporary measure to get it back up and running.  Now that the Duet was in and I was using high microstepping ratios, I expected quiet operation and was bothered by the noise.  I looked closely at test prints and found the vibration in the X axis was causing closely spaced vertical lines in the X parallel sizes of prints.

The problem had nothing to do with the Duet board.  It was a result of some small metal flakes getting into the motor and interfering with the motion of the rotor.  I wrote a separate blog post on that.  That problem was easily fixed, once I knew what was happening, and the X axis now runs quieter than it ever did thanks to the 128:1 ustepping in the Duet board.

Here's the inside of the electronics drawer now that the Duet is in place.  I know, it's ugly, but it's really easy to service, especially now that I have all the wires labeled.  I used this type of label- they are really tough.  I tried using them in a laser printer and found that the fuser heat distorted the labels and they tended to peel apart and even curl off the backing sheet, so I decided to just write on them with a permanent marker instead and had no further problems.  UMMD will get the same type labels the next time I have a reason to open the electronics enclosure.

Inside the drawer- no more 32V supply and DSP driver for the Y axis.  I used a custom splash screen that is displayed for a few seconds every time the printer is powered up.