Filament Spool Change During a 3D Print

I successfully made a filament spool change mid-print. Several of my 3D prints have been previously ruined when the machine ran out of filament. Now I am thinking of sensors I could build to pause printing and move the extruder head when the filament is about to run out.

I also want to point out that when the filament spool comes to an end, the machine keeps trying to feed filament and the last part is stuck inside of the extruder head. Now that my machine is water cooled, this forces me to do some annoying disassembly and reassembly. It is much better for me to extract filament since I can do the operation externally with no disassembly. That’s what I was able to do this time.

Here are the steps I used to make this work. I was using Pronterface. I was doing an SD card print, but I left the PC connected to the Arduino through USB. I was keeping the PC on to run a webcam that monitors the print, so I could still interact with the board at any point. This experience shows me that I should probably keep the PC attached unless I need to use it for something else during a print. If it is disconnected, reconnecting will interrupt the print. Also, knowing machine coordinates is critical in the following process.

1. Click “Pause” in Pronterface
2. Use M114 to get all machine coordinates. Write down positions for X, Y, Z, and E (extruder)
3. Move the extruder up +10 in Z (Pronterface button)
4. Retract the old filament
5. Install the new filament. Run the extrusion until melted filament is coming out. Clean it up.
6. Use M114 again. Note that the value of E has changed due to retraction and extrusion
7. Use G92 E… to put the extruder coordinate back to where it started. THIS IS IMPORTANT!
8. Close the heated chamber and let the printer stabilize.
9. Move the extruder back down -10 in Z (Pronterface button). All coordinates should be back to their original values.
10. Click “Resume” in Pronterface
I switched from white filament to black filament from a different manufacturer. I noticed that the ooze characteristics of the black filament were much worse than the white filament. I think that every filament has optimum extrusion temperature and probably other optimum parameters like speed. I will note the manufacturer and type of filament I was using originally since it was working so well with my current configuration. Black was OK, but not great in comparison.

This is a 3D print of a Colt 45 model 1911 A1. I downloaded the design from CNC Gunsmithing.

If I could print metal, or perhaps use this plastic model for casting, I might be able to produce an actual Colt 45.

Here is a Blender rendering of the parts before I converted to STL.


If you don’t have the software necessary to convert all of the parts to STL, or if you don’t want to arrange them all for your printer, you can download the STL from me.

Here is the model with support material (mostly) removed. Note that the black filament did not perform nearly as well as the while filament. I don’t remember where I found the black stuff, but I will be ordering several rolls of 1.75 mm ABS white from I don’t work for them or anything. I’m just sayin… obviously, that’s what worked here.

To review, I run a heated chamber at 70C. The heated bed is also at 70C inside of the chamber. My extruder is a Stepstruder MK7 that I run at 230C.

NOTE: After printing everything, I found that this slide DOES NOT fit this body. I will need to read the web site in more detail and try to locate the matching parts. The handles DO fit the body.



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