Hi guys !
First, I hope you are fine and your family too.

I did not post anything since a long time.
I dropped a few 3d printed parts to volunteers assembling face shields for people fighting the coronavirus.
I am pretty amazed how fast the 3d printing community reacted and how big it is becoming.

https://www.chopchop3d.com/images/gallery/91613335_160209522115776_902046465091497238_n.jpg

**How to print *"quickly and reliably"* ?**

I put quickly in bracket, because of the speed and the throughput.
Yes for the throughput, speed matters but at what risk: reliability of the print and reliability of the machine.

Safe Slicer settings:
- *Larger Extrusion Width* (Nozzle: 0.4mm -> 0.5mm, 0.6mm -> 0.72mm, 0.8mm -> 1mm): the geometry of the tip of your nozzle  and the geometry of the part to print is the limiting factor.
- *Larger Layer Height* but not overdo it ( Nozzle: 0.4mm -> 0.28 to 0.32mm, 0.6mm -> 0.4mm): some tuning is needed, the part can become too weak (see cooling/temperature parameters)
- *Tune number of perimeters/insets*: given the geometry and the extrusion width you can manage to reduce the number of passes made and reduce/avoid the slow shaking movement of the top/bottom or the gap filling (overlap setting is your friend)
- *Use Concentric infill for Top/Bottom layers*: linear infill or zigzag  infill will just take more time
- Cooling  parameters: *No fan on PETG print* for instance, try to reduce it, it makes stronger parts and you can print faster. Set the *print time per layer* down to 5 or less seconds.
- Keep the same print speed all around, if there is a bit of ringing it does not really matter.
- Keep a safe margin on the extrusion throughput, go to max 75% to 80% of the theoretical limit (https://www.printitindustries.com/pages/print-speed-calculator)
- Print with higher temperature but don't overdo it (retraction can become ineffective after a threshold)

**Example printing a single part on PETG at 230C on an Ender 3:**
Standard Print Speed 40mm/sec, Retraction speed 25mm/s with 6mm
Layer Height 0.2mm with 0.4mm extrusion width, base line 2h22m
- Same speed with larger extrusion width + cooling settings + concentric top/bottom infill:
  0.4mm to 0.5mm with 0.2mm layer height: 1h52m
- Same speed with larger layer height (0.5mm extrusion width instead of 0.4mm):
  - 0.24mm layer height 1h33m
  - 0.28mm 1h22m part good
  - 0.32mm 1h12m part correct
- Increasing speed from 40mm/sec to 50mm/sec
     - 0.32mm 1h05m (part too weak, start to have under extrusion after short retractions sequences)
     - 0.28mm 1h12m part correct

What about reliability ? 2 minor failures only caused by me ^^
Same quality of the prints over and over, print start and you go.

Happy 3D Printing !