24 Dec 2018 Update:
Modified Camera Mount including camera housing to accommodated Prusa's R3 Canted Cooling Fan.
This required a longer standoff from the print bed which in turned required stiffeners to dampen out vibrations during high speed printing. Also modified the way the camera housing mounts to the standoff.
The Prusa i3 MK2S is a great printer especially for the hobbyist or light industrial desktop user. That having been said it is a raw printer without a lot of accessories that would make it a great printer. The is the forth in a series of accessories that I designed for the i3. The others are:
The Prusa i3 MK2S printer's primary input is via a standard sized SD card. The card supplied with the printer contains a number of utilities and sample prints but the logistics of moving designs to the printer is cumbersome at best particularly if the printer and the workstation are not close by. Also provided is a standard USB Printer Port that can be connected to a print server.
Although full size PC's can be used to host a print server, there reliability as a print server is less than desirable unless they are dedicated to that task. A better solution is to use a small but powerful computer on a chip board such as the Raspberry Pi (RPi). The Raspberry Pi Zero W contains all the necessary interface to provide wireless print serving along with a camera interface which supports a low cost 1080P pin hole camera.
This design includes an Uninterruptible Power Supply (UPS) for the RPi. While this is not absolutely necessary, it is good practice with Linux based computers. Much like Windows, Linux can corrupt files if not properly shut down before power is removed. The UPS has enough capacity to operate for several hours after power is interrupted. This is very useful in areas prone to power outages that would otherwise destroy long print runs. At idle the OctoPrint Server consumes 0.230 Amps. During the average print run OctoPrint draws 0.350 amps. Peak consumption (0.450 amps) occurs during Time Lapse Movie generation at the end of the print run.
An alternative to using an on-board UPS would be to use an external unit.
OctoPrint (OctoPrint.org) is a free Linux based print server designed for the Raspberry Pi computer, among other platforms, and is licensed under the Affero General Public License. The latest version can be downloaded and executed on the Raspberry Pi Zero W without modification. See the OctoPrint.org site for details on downloading and setup.
Be sure to order the Raspberry Pi Zero W and not the Raspberry Pi Zero. The "W" version includes a high speed WiFi adapter which obviates the need for a USB Bridge and External WiFi adapter.
This design requires the builder to have some soldering capabilities and skills. Please review the construction steps carefully before proceeding.
There are a number of horizontal slots in the vertical sides of the RPi case that are 10mm or more in length. The Prusa i3 handles this with minimal sags on the 1st layer over the void but some printers produce unacceptable results due largely to lack of extruded filament cooling. If you have difficulties printing the case, turn on supports.
Step 1: Print the Raspberry Pi Zero Case and Camera Mount
This is fairly straight forward and requires no support structures if printed on a 3D printer that can handle 10mm overhangs.
Trim off any extraneous extrusions that may have occurred during the print process.
The Case Top is a pressure fit to the Case Bottom and requires no hardware. The same is true of the RPi Camera enclosure. Hardware is required to mount the Raspberry Pi Zero W and the Geekworm UPS Hat to the Case Bottom, and the Camera Mount to print bed.
Step 2: Prepare the Raspberry Pi Zero W
Solder the 40 Pin Header Connector to the underside of the Raspberry Pi Zero W. This is opposite the conventional way the connector is installed and is necessary to allow the battery to be positioned between the RPi and the UPS boards.
Care should be taken not to bridge solder between pins on the RPi board. See area circled below:
Raspberry Pi Header Connector Detail
Step 3: Install the RPi onto the UPS Board
Carefully install the RPi board onto the pins of the UPS Board. Visually inspect the connections to Insure all 40 pins are inserted into their respective socket on the RPi. It is easy to install the boards off one row or one column.
Step 4: Install Battery
Position Battery between the RPi and UPS boards as depicted below. Insert the Battery Connector into the socket on the UPS board as indicated.
If the RPi is powered up when the battery is connected Press the On/Off switch for approximately 0.5 seconds. Holding the On/Off button longer than 1 second will power the UPS and RPi on again.
UPS ON/OFF and Battery Connection
Step 5: Prepare Control Box Bottom for Electronics
Insert a M3x10 Counter Sunk Flat Head screw into the Control Box as indicated. Insure that the screw will freely move in and out. This screw will be positioned against the UPS On/Off button and will afford control over the UPS once the electronics are installed.
On/Off Plunger Detail
Step 6: Install Electronics
Hold the Plunger Screw inserted above tight against the inside of the Control Box and slide the Electronics assembly, built up in the previous steps, into the Control Box left side first so as to engage the Plunger against the *On/Off button.
Ease the Electronics right side into the Control Box such that the entire assembly is fully bottomed out against the bosses built into the Control Box.
Secure the electronics with two M2.5x20 Cap Head Screws as shown below.
Attach the Camera Zero Insertion Pressure (ZIP) ribbon cable into the slot provided on the RPi board. It is necessary to first release the jamb strip on the top outside edge of the connector. After inserting the ribbon cable this strip must be pushed back to its original position in order to secure the ribbon cable in place. Lightly pull on the Ribbon Cable. If properly installed it will not come out of the connector. See below.
Electronics Case Detail
Step 7: Mount Electronics Control Box and Attach Cables
Install the Control Box onto the Left Hand i3 Frame Threaded Rod using 3 Cable Ties as indicated below. Tighten Cable Ties as much as practicable to prevent the Control Box from rotating on the Threaded Rod when the printer is moved.
Install the Printer cable into the USB connector on the RPi as indicated below. Attach the other end to the printer in the USB port provided.
Install the USB power cable into the UPS as indicated below.
Install the Micro SD card containing the Octoprint previously download from the OctoPrint.org site (http://octoprint.org)
Install the top Control Box Cover by pressing it in place. No hardware is required to secure the cover.
The RPi gains power from the UPS via the 40 Pin GPIO connector. The RPi PWR USB port is not connected in this design.
The UPS Battery charge state is indicated by the four LEDs shown below. Each LED represents 25% charge level (e.g. 3 LEDs - 75% charge). These lights are visable through corresponding holes in the left Control Box side.
A single green CPU Run LED is visible at the right side of the Camera cable opening.
Step 8: Install Camera Mount
Install Camera Mount onto the bottom left hand forward Build Plate screw using M3x12 Cap Screw. Position the mount as fully engaged with the build plate frame as possible while insuring clearance with all other printer features. See right hand picture below.
Lightly sand the Leg Post and square portion of the Swivel so that when assembled the camera will pan and tilt smoothly but not so much as the mount moves easily in either direction. Some friction is necessary to prevent camera movement during printing.
The Camera Mount must clear the Cable Tie holding the LH linear Rod to the printer frame.
Camera Mount to Printer Detail
Step 9: Mount Camera
install the Camera Cable into the Camera Module in like manner to above. Place the Camera Module into the Camera Case and snap the Camera Case top into the base insuring the camera module is properly and securely positioned and held in place. The top is designed to be an interference fit and should not fall off without being pried loose. See below:
Bend the ribbon cable around the top and down the back leaving about 10mm loop to act as a strain relief. Secure the ribbon cable to the back of the Camera Case using double sided tape. See below.
Camera Case Detail
Step 10: Install Camera
Install the Camera Case on the Camera Mount as indicated below. Point the camera in the general direction of the build place. Fine Tuning can be accomplished using the Time Lapse setup wizard in the Octoprint application.
Camera Installation & Cable Detail
Step 11: Configure OctoPrint
Configure the OctoPrint application via a browser at Octopi.local
OctoPrint configuration Main Menu
Print a Test Case
Below is a short time lapse video how the build of the Top Print Server Case:
OctoPrint Case Time Lapse
Bill on Materials