Retract Test part
Test part used to test the retract settings. This model is different from the test part : Retract-Tower. It is faster to print but allows to test only one set of parameters. With a thin and conical part the printing time will decrease with each layer. This test should therefore also allow you to test the influence of the parameters related to the Minimum Layer Time.
- Enable Retraction : True
- Nozzle Size : 0.4
- Layer Height : 0.2
- Initial Layer Height : 0.2
- Line Width : 0.4
- Wall Line Count : 3
- Top/Bottom Thickness : 0.8 mm
Printing Time = 7 mn
Print the part and check if you have some strings on your part. If it's the case try to use the retract tower to find the right settings. You could also try to change in CURA directly the parameters to find the best settings to suppress this strings. The most important parameters you should check in your slicer to minimize the stringing are the following:
- Temperature
- Retraction distance
- Retraction speed
Temperature is a vital factor and probably one of the 5 most important settings in your profile. If you have a lot of stringing you are almost certainly melting at too high a temperature. Remember that all materials have a range of temperatures in which they can be printed, so try lowering the temperature and bringing it closer to the lower limit recommended by the manufacturer.
If you are already using a very low temperature and still have stringing, check the following points :
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While it is not possible to “suck” plastic out of the nozzle, as no negative pressure can be created, it is possible to minimize the pressure on the nozzle by pulling the filament out of the hot zone of our hotend. The shrinkage distance is very dependent on our printer, as both the melter and extruder and the type of extrusion (direct or bowden) must be considered. Most bowden printers perform well with a shrinkage value between 3 mm and 6 mm, and direct extrusion printers between 0.5 mm and 2 mm.
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The speed of retraction is another important factor, as the higher the speed the lower the stringing. This speed will depend on the motor of our extruder and also on the type of extrusion. Generally values between 40 mm/s and 60 mm/s usually works fine.
The Minimum Layer Time configures the shortest duration of printing a layer that is allowed. The printer is not allowed to print layers any faster than this.
This is necessary in order to allow the previous layer to cool down before the next layer gets put on top of it. This ensures that the previous layer has completely solidified, to prevent sagging. Insufficient cooling of the layers can also produce stringing by the material that can stick to the nozzle. It may therefore be necessary to adjust this parameter to reduce your problems with stringing despite a good retraction parameters adjustment.
If you want to use a more difficult test we recommend the Retraction/string test : https://www.thingiverse.com/thing:3518195 This part is much harder to manage and often if you have managed to eliminate all the wires on this test part, this new test case will push you a little further in your settings.
