6.3. Maximizing output part 1: print, filament, and printer settings

Maximizing output requires more than just setting faster print speeds in your slicer. These notes show how slicer print, filament, and printer settings can be optimized to reduce 3D print times.

This page captures my notes following a lengthy thread on the Prusa forums on how to optimize print times for large, functional prints.

Note

These notes are based on my experiences with the Prusa i3 Mk3 and Artillery/Evnovo Sidewinder X1 printers. If you are using a different printer, please verify the hardware details are similar.

6.3.1. The challenge

The question was specifically on a cylindrical print that was taking an estimated 6h5m to print. Here are the original settings.

Typical |PS| settings — Fig. 6.35 Typical *PrusaSlicer* settings

The print was being done with typical settings for a 0.4mm nozzle:

2 perimeters at 0.45mm width.
Sparse infill at 15% density.
0.15mm layer height.
PETG filament.

A few things are apparent:

Walls are printed with 2 perimeters at 0.45mm width resulting in gaps between inner and outer walls. These are being filled with sparse infill, which slows down printing significantly.
The fine 0.15mm layer height is slowing print times significantly due to the increased number of layers to be printed. Some detail is desired for the openings in the vertical walls, but most of the print consists of simple vertical cylindrical shapes.

6.3.2. Optimizing layer heights

I switched over to my typical 0.4mm profiles which set:

3 perimeters using auto (0) extrusion width. This allows the slicer to select an extrusion width based on the size of the mounted nozzle.
Sparse infill at 15% density.
0.15mm layer height.

These changes actually increased the print time to over 7 hours. Not surprising considering all I had done at this point was specify an additional perimeter. The reason I wanted to use my profiles was to take advantage of variable layer heights (VLH)*. VLH allows the slicer to select lower or higher layer heights based on the difference between the layer currently being printed and the layers below. If the part varies considerably between layers, lower layer heights are used to preserve vertical detail. If large section of the part don’t vary, higher layer heights allow more filament to be printed in the same move, decreasing speeds.

Fig. 6.36 Applying variable layer heights

This adjusted the print to use larger layer heights where little detail is required (the red bits are 0.32mm) and lower layer heights where more detail is required (the green bits are 0.1mm). Here’s the result after using VLH with the default settings.

Fig. 6.37 Slicing results after applying variable layer heights

At this point, print time dropped to 4h38m, a reduction of 87m from applying a single feature with default settings. Several changes are apparent:

Using 3 perimeters at 0 (auto - slicer calculated) width, the hollow space between the inner and outer walls has been made solid with extra perimeters and gap fill. The resulting part should be much stronger.
Using VLH, low layer heights have been limited to those areas where it will make a difference. Higher layer heights have been used to reduce print times elsewhere. These are fairly minor tweaks that have a big impact both on print time and print robustness.

6.3.3. Increasing maximum volumetric speed

Next I tried essentially the same settings with some tweaks based on experience with PETG filament. From prior experience using PETG to print PPE, I knew that PETG can be pushed well beyond the settings specified in most default profiles.

PETG flows more quickly at higher temperatures. Higher temperatures can allow faster printing without strength degradation. I bumped the printing temperature to 240C.
The normal Prusa default values for Maximum volumetric speed (MVS) for PETG are around 8 mm³/s, primarily for good infill results. If you are not printing with infill, higher MVS rates can be used. I increased MVS slightly to 15mm mm³/s. Note that you should test this value with your filament and select a value well below the maximum rate at which your extruder can push filament.
I bumped perimeter and top infill speeds from my usual 25mm/s for quality to 45mm/s for speed. This can probably go higher.

At this point, the estimated print time dropped to 3h19m, a savings of 166m by adjusting settings based on my familiarity with the selected filament.

6.3.4. The Need for Speed: maximizing hardware

Finally, we can realize further time savings by using a larger nozzle and tuned print and filament profiles to take advantage of the larger nozzle’s capabilities.

I selected a 0.6mm nozzle profile with a minimum layer height of 0.1mm and a maximum layer height of 0.48mm. These are the settings that determine the minimum and maximum ranges to be used with variable layer heights. A larger nozzle allows a much wider selection of layer heights.
I selected a “Max PPE PETG” profile printing at 240-245C with MVS of 28mm^3/s (the result of a lot of testing). This is my “print as fast as possible” PETG profile. Quality is acceptable, but not exceptional. Fine for this print.
I adjusted the default extrusion width to 1mm.
I reset and readjusted VLH for the part.

The print time estimate is now down to 1h58, a savings of 354m from the original settings.

Fig. 6.38 Slicing results after switching to 0.6mm nozzle and high throughput settings

Notice the following:

Walls are being printed with 3 extrusions as opposed to 4 or more due to the wider extrusion widths. This save considerable time.
Layer heights are now distributed from 0.1 to 0.48mm corresponding to the minimum and maximum layer heights specified for the 0.6mm nozzle.
The base is now solid with no sparse infill. The walls are thick and strong. The print should be more robust overall.

Now I’m not saying you should immediately start using these settings, or guaranteeing great results using them. I just want to emphasize the fact that if you get to know the limits of your slicer, printer, and filament, there are relatively minor tweaks you can make that will make a huge difference in print time. The acceptable balance of quality-versus-speed is something only you can determine.