3D Printer interruptions are rare but not unheard of, especially if you are running multiple memory-intensive applications or if you have multiple USB peripherals. When this happens you can usually take note of the last instructions sent to the printer before it stopped and modify your G-code in order to restart from the appropriate line.

In this article, we will guide you through the steps we use to salvage interrupted prints using Repetier-Host.

The salvage method discussed in this article will only work if your slicer setting had the extruder set to relative mode (in the Dimension Tab of SFACT) when the print was interrupted.

The first step is to wait a little while as your computer may have only stopped temporarily while it processes other applications. If the printer resumes without any intervention then you should probably reduce the amount of programs that you are running or allocate a higher priority to Repetier-Host. In the event that your printer does not resume, your next action should be to raise the hot end from the printed section. If the printer is unresponsive, disconnect and reconnect. Raising the hot end is a necessary step to prevent any melting that could damage your print.

The next task is to find and record the last instruction that was sent to the printer before it stopped.

To accomplish this you will need to take a look at the bottom of the Repetier-Host interface for the log window. From the log window select the “Send” function (or the “Commands” function for Microsoft Windows) and scroll down to the last line.

The next step is to locate this line in the G-code window. Because of the way the slicer works, there will only be one corresponding line for each command sent (including X, Y, Z and E instructions). Different approaches can be taken to find the corresponding line, but the simplest way is to use an external text editor with the “Find” function. Follow these steps:

1. Copy the entire G-code from the Repetier-Host G-code editor window into your favourite text-editing program and then use the “Find” function of the program to find the last G-code  line that was sent. Once found you can delete all previous lines and keep the subsequent lines.
2. You must add the M83 command to the beginning of the G-code before the first instruction. This sets the extruder to relative mode.
3. Before restarting the print, re-home your printer and make sure that the hot end is pressurised by extruding some plastic.
4. Move the hot end above the partially extruded part. This will ensure that the hot end does not hit the already printed material.
5. Press the Run button.
6. In the case of the Rostock BI V1.0-2.5 you can press Home All and hit the Run button for steps 4 & 5.

There you go! You saved your print and didn’t waste any material.

There are a few additional issues that will result from this process:

• The estimated time left to print will be inaccurate as the information used to calculate time is in the G-code section that has been deleted.
• Do not adjust your end stops during this process or the part will not resume properly (it will shift).

Enjoy!