Retraction Test
Retraction Test
I read through the Orca Slicer manual on github, but I don't understand how the retraction test works. I have no idea how I'm suppose to distinguish the results. Would anyone like to explain in layman's terms what it is I'm looking for?
Extrusion works by the motor pushing the filament forward, causing pressure behind the nozzle, and the filament melting and extruding out the end. When your printer wants to stop extruding ( ie moving to a new part or section to print without printing anything in the middle), it makes a retraction to pull the filament back, releasing the pressure behind the nozzle, and stopping the filament from extruding out.
In a perfect world, a full retraction would not be necessary; not pushing the filament forward should stop the pressure buildup, and stop the filament from flowing. However, we don't live in a perfect world, and so backing the filament up a small amount is necessary to stop it from flowing.
Finding out exactly how much you need to back the filament up is the purpose of this test. Back the filament up too much, and you can create clogging issues, extrusion issues caused by the filament not being at the end of the nozzle at the beginning of the extrusion, and (slightly) increased print time; don't back the filament up far enough, and filament will continue extruding out the nozzle, causing stringing.
The test works by having you lower your retraction distance to a very small number ( a lot of tests will have you disable retraction altogether, ie 0 mm), and slowly increase it from there. The idea is that the bottom of the tower will look like hot garbage, and slowly improve as the retraction increases; what's the quality stops improving, you know that that is your ideal retraction distance.
If you have a Bowden tube setup, a good retraction Tower would have values ranging from 0 mm to around 10 mm. Direct drive extruders need far less retraction; 0 to 2 mm in 0.2 mm increments should be good. Again, you're looking for the first setting that gets rid of stringing.
Let me know if you need any help or have further questions! Retraction can be really tricky to understand mechanically, but can be important for improving print quality and reducing the need for post-processing.
I must have done something wrong because the whole tower looks pretty much the same except for a clear overextrusion around the middle on one side. The rest have really thin barely visible strings that don't go very far.
I don't use orca slicer so I'm not familiar with how it works specifically, but are you sure that the retraction settings are actually changing between different sections? I made the mistake when I first started it just loading the model and letting it print with default settings from my slicer. If the GitHub doesn't specify exactly how to enable the retraction tower settings, I would look up a guide on YouTube. If you've done temp towers, it'll likely be set up in a similar fashion.
If your test starts at 0 and you don't see any difference, it definitely it not working as intended; 0 retraction with result in a huge stringy mess, and going to the next step will be a significant change.
Edit: also maybe make sure that you are using the correct values for testing according to your extruder setup; if you are using a direct drive retraction tower on a bowden setup, the changes will be too small to make any discernible difference, and the lowest setting on a bowden test will likely be too high for a direct drive.
I've had the same thing. I think orca's retraction test is just too 'easy'. I think the towers are too far apart.
Wasn't aware of the test (SuperSlicer user here), and found this.
The tower has multiple notches, each one corresponding to a different retraction length. By looking at the tower after printing, you can see how each retraction length affects the print quality.
So check your surface finish and select the retraction value with the best looks.
The print is so small and I literally cannot see the results. I can't even photograph it clear enough with my camera phone.
That is not how it is supposed to look, the end result should be at least a couple of inches wide.
From what I understand it tests the minimum retraction distance you need to avoid stringing. The lower you get the less retraction you need. For example, for me usually it stops stringing around 0.4mm retraction (that's 4mm measured from the hot plate), but found that in real conditions the default 0.6mm works better. I don't find this test too useful, for me it fails to demonstrate the spectrum between too little and too much retraction, a feature I appreciate in the pressure advance tower. Apparently the moment it stops stringing, anything after that won't show you anything new and it's best to stop the print. Either that or I fail to notice any defects when the retraction is relatively high.
I'd give Teaching Tech's calibrations a try. His website has a great guide for tuning every part of your printer. Teaching Tech 3D Printer Calibration