Speed & Flow (Extrusion) Check

This model is for testing your extrusion and flow. See the following instructions and backgrounds how your speed will be effected.

The print speed has several variables

How the print speed is effected by your material:

1. Temperature:
   The higher the temp is, the faster the material can melt, the faster you can print. With higher temperatures, you also change the viscosity of the melted filament inside the the hot zone.
2. Viscosity:
   The more material is pusshed through the hotend, the more force will be needed. With more force it can be that the filament is slipping at the drivewheels of the extruder which will leed into an underextrusion at high flow rates if you dont change the temperature for lower viscosity.

How the speed is effected by your printer:

High speeds are not suddendly there. To reach the high speed, the extruder increases its speed until its reaching it. this has several variables too which will be discussed in the following.

1. Weight of the Printhead:
   the more weight has to be accelerated, the more force the stepper must provide. At some point, you reach the maximum bossible acceleration due to the weight of the extruder.
2. Acceleration settings:
   if you dont reach the maximum acceleration of your printer, you can change your acceleration at your slicer settings or printer settings. The higher the acceleration, the earlier you reach the high speeds for this test. However, if you have too high acceleration rates, it can effect your normal prints in a negative way.
3. Your nozzle:
   The nozzle is the bottleneck of your extrusion. A high quality nozzle has optimized flow characteristics which helps the extruder to push the filament through.
   By using a special nozzle like the CHT Nozzle, you can reach a higher extrusion flow than a cheap no name nozzle and an even higher flow rate than a branded quality nozzle.
4. Your extruder:
   Sometimes the extruder can't provide enough force and skip some steps. This is a proofe that the maximum force of your extruder has been reached. To solve this, you can lower the viscosity and rise the temperature to help the extruder pushing the filament through the melt zone and the nozzle. 
    

There are different radius in this test:

• 10mm radius on the left
• 20mm radius on the right
• 30mm radius in the middle

Check the print behaviour on each corner. if it looks nice and clean, you are on the safe side. If the print starts to fall into the corner like a motorbike, you reach the maximum flow rate of your material under the current conditions.

Check your straight line extrusion:

In the middle of each path, the extruder reaches the maximum speed and flow. Check the single wall, if there are gaps. If so, it could be that the extruder is skipping. Use the information provided above to calibrate your printer for high flow rates. Otherwise you have found your maximum flow of your current printer hardware setup. 

Recomended settings:

• Bottom layer: 1
• initial Layer: 40mm/s (or with a standard Extruder 20mm/s) choose a safe speed!
• layer height: 50% of your nozzle size
• Wall speed: 10mm/s (will be constantly increased during the print)
  • outer wall & inner wall the same
•  change to vase mode!
  • enable spirilize outer contours
  • enable smooth spiralized contours
• print temperature:
  • it depends on your material. check your temp tower

How to change your print speed:

• At the printer:
  You can change the printspeed directly. If you have set your wall speed to 10mm/s, you can change the speed setting on the printer during the print to 500% which means, you get a print speed of 50mm/s. Due to no travle moves, this setting is safe while printing
• At your Slicer:
  Use your post gcode processing to change your print speed at a defined print height.