Printer Pausing, Skipping, Stopping and Losing Position

I’ve seen posts from people with similar sounding problems who have tackled them with a different solution to us, so I’ll share our experience of it.

We originally ran our printer off of our CAD computer but decided to repurpose one of the half size Dell office job PCs to be a dedicated printer computer. We only experienced pauses on the CAD compute when we were running our electromagnetic FEA software, which is very resource heavy, hence why we decided to move it once we started running FEA on a regular basis. As for the printer stopping all together, we only found this when using a long USB cable and had no problems when we went down to an 18" one. We only experienced one skip and loss of position and that was during an FEA run too.

The half sized Dell was originally Windows Vista but we ended up doing a clean boot of Windows 7 on it as Repetier did not run very well at all on it. Repetier ran on Windows 7, however it was very slow to open up and then even slower to load STL files into it and would fail completely to load large(24+ hour) G-Code files off of our network. It also had a really had time just clicking onto the G-Code tab, whether it was empty or not.

Once you had waited through all of the loading the printer would run successfully except it started pausing frequently and occasionally stopping. Checking the performance of PC we found that Repetier was using up pretty much all of the RAM and the majority of the CPU and the pauses/stops were occurring whenever we attempted to use the computer, including click on the Repetier window or waking up the computer screens. As a result we decided to max out the RAM on the computer from 1GB to 4GB(3 and a bit useable). This stopped any of the pauses or skips as well as sped up the opening of Repetier and the loading of STL files, however G-Code files were still bad to load. In addition, we also stopped the computers screens from evening sleeping, just avoid startling the printer when we woke them up. The printer still skipped and lost its position on the odd job too.

When on the original CAD computer, Repetier had supported fast rendering for VBOs but the little Dell PC did not support it. This seemed to linked to the graphics card so we replaced the 512MB workstation graphics card with a 2GB gaming graphics card with GDDR5 that we found cheap on Dabs. With this new card installed Repetier can now seamlessly click on to the G-Code tab as well as load G-Code files from anywhere on the network; the time taken between selecting to run a job and the actual printer starting it seems to be reduced too and we have not had any skips of the motors or lost positions. Another benefit is that up until now the graphic of the print job would not work but now it is tracing the movement and actions of the printer like it used to on our CAD computer.

Annoyingly our printer has hit a different problem and is currently out of action so I am reluctant to say this certainly stops the printer from losing its position as we haven’t had a decent number of runs to check but it certainly seemed to help and solved some other issues for us.

Hopefully this helps and provides a possible alternative solution for some of you.

FWIW, Im also using an old laptop without supported GPU and too small amount of ram (1.5GB) for repetier to run the printer. My observations when using complex models:

  • it will cause slow downs or even short pauses in the printing when manipulating the 3D view or switching between tabs
  • Slic3r will run out of memory when doing huge slices, resulting in incomplete gcode. Top layers will simply be missing. YOu can still print and it will correctly print the lower part of the object, then it just stops, because there is no more gcode. Maybe this is what you experienced? THere is a warning in the console when this happens but its easily overlooked (I know I did).

However, when I slice the model on a different PC and load in the gcode on the laptop, it does work, and Ive not once seen it “lose its position” for reasons other than the nozzle hitting the printed object. THere are other reasons that may cause it, including overheating pololu’s and vibrations causing the position microswitches being triggered. But I doubt an underpowered laptop will cause this.