How To Backup the Onefinity Micro SD Card

How To Backup the Onefinity Micro SD Card

The two procedures below will cover how to make a backup copy (image) of your current Onefinity Micro SD card and how to restore it (flash it) to a new Micro SD card. The new Micro SD card can then be used in the machine and the original can be safely stored away. This can be useful for advanced users that poke around under the hood doing unsupported modifications. Please note Onefinity explicitly states in the post linked below that flashing a Micro SD card is only for advanced users or if you were directed to do this by Onefinity support.

To perform these procedures you will need the following

  1. A Windows computer with at least 32 GB of free disk space
  2. An SD card reader in the computer with a Micro SD adapter OR a USB card reader with Micro SD adapter if necessary and an open USB port on the computer.
  3. A 3mm hex key for opening the Onefinity Controller.
  4. A new 32 GB Micro SD card with the same specs as the original Onefinity Micro SD card if you wish to flash the backup onto a card…


The Micro SD card supplied with the machine is 32 GB in size and contains the Raspberry Pi operating system, the firmware Onefinity adds to the operating system to make it a Onefinity, settings which you most likely have changed, and the gcode files that accumulate as you use your machine. Using a free software program, you can create an image of the Micro SD card. The image created is a single file that can be stored just like any other file. The drawback is the file size will be almost as big as the advertised Micro SD card size. In my case the file size was 31,166,976 KB (29.7 GB). This file can be compressed in a separate step after the image creation is complete. My tests showed the 29.7 GB file compressed down to 1.31 GB in under 4 minutes using Windows Explorer compression features. This compressed size will vary depending on the number of gcode files on your system.

This paragraph is based on my assumptions and can’t be taken as fact. Onefinity creates a new image of their system (the operating system and the Onefinity firmware) each time they release new firmware. They use this image to flash the Micro SD cards that go into new machines. The image they create is just under 4 GB because their originating file system is sized just large enough to hold the operating system + the firmware. When the new machine is first booted, the file system expands to be as large as the Micro SD card it is stored on.

The software I am using for this procedure is Win32 Disk Imager on Windows. The software Onefinity recommends in the video found in the linked post above for flashing images is balenaEtcher. Unfortunately balenaEtcher does not support creating an image from an SD card. It does however support cloning a Micro SD card to another Micro SD card. I have tested this and it works well. The downside is you must be able to have two Micro SD cards inserted into your computer at once and it can be confusing as to which one is the source and which is the target. You risk overwriting the original Micro SD card if you are not extremely careful. Mac users need to use ApplePi-Baker. I won’t be covering this here but the linked page has instructions. I tried it and it worked perfectly. It also has the added advantage of being able to compress the image as it is created. The compressed image it created from the 32 GB Micro SD card during my test was 1.54 GB.

Procedure to Create a Backup Image

  1. Download and install Win32 Disk Imager

  2. Remove the Micro SD card from the Onefinity using this video by Onefinity. Stop at 0:38 in the video and continue with step 3.

  3. Insert the Micro SD card into the computer
    IMPORTANT: NEVER Click a button that says “Format disk”. Windows will pop up at least two dialogs telling you that you need to format the disk. They lie, you don’t need to. Don’t do it.
    Windows will assign 2 drive letters to the card.
    If a USB card reader is used, the drives will show up as USB drives.
    If an SD card adapter is used in a slot in the computer, 1 drive will show up as an SDHC drive and the second drive will show up as a removable disk.

  4. Start up Win32 Disk Imager
    Windows may pop up a dialog asking if you want to let this app from an unknown publisher make changes to your device. Answer Yes

  5. Fill in the “Image File” box with the name of file for the new image.
    Refer to the image below.
    NOTE: This program accepts both forward and backward slashes in file names.
    The images supplied by Onefinity are of the form "onefinity-raspi-x.x.x.img where the x.x.x is the firmware version. I append a “My” to this format. You are free to use whatever naming convention you like.


  6. In the “Device” dropdown, select one of the two drive letters assigned to your Micro SD card when you plugged it in.

  7. Click the “Read” button
    The read rate is shown at the bottom as well as a time estimate. With my USB card reader I was getting about 18MB/s (must be USB 2). With my SD card adapter, I was getting 70MB/s.
    On my system, the USB card reader took 27 minutes to complete. The SD adapter took 7 minutes to complete.

  8. When complete click the “Verify Only” button.
    The verify process takes as long as the read process to complete.
    If the verification fails, the image is no good and should be deleted.

  9. Optional: Using Windows File Explorer, right click on the newly created file and select Send to > Compressed (zipped) folder
    You can delete the 32 GB original file once compression has completed.

  10. Eject the SD card by going to File Explorer and right clicking on one of the drive letters and choosing “Eject”

  11. Remove the Micro SD card from the reader

  12. The original Micro SD card can now be inserted back into the machine using step 12 below or placed in a safe location as a backup if you intend to flash a new card and use that card in the machine.

  13. Refer back to the Onefinity Video to reinsert the card into the machine.
    Instructions start at time 1:43 in the video.
    Skip this step if you are going to turn right around and flash the image to a new Micro SD card for use in the machine. Refer to the procedure below.

Procedure to Restore Backup Image to Micro SD Card Using Onefinity Video

  1. Insert the new Micro SD card into the computer.
    Do not use the original Micro SD card unless you are an advanced user or are directed to do this by Onefinity support.
  2. If you optionally compressed the file, using Windows File Explorer, right click on the file with the “.zip” extension and select “Extract All”.
    NOTE: You must have at least 32 GB free disk space to perform this step.
    The balenaEtcher program supports zip files however it doesn’t like zip files created by Windows File Explorer.
  3. Refer back to the Onefinity Video to flash the new card.
    Instructions begin at 0:45 and end at 1:42 in the video.
    NOTE: The only change to the video instructions is to choose the image file you created when the presenter says to choose the downloaded image.
    If you intend to put this card back in the machine, you can go ahead and watch until the end of the video for instructions on how to insert the card back in the machine,