This retraction test is divided up into 9 equal sections with small tabs, so you can compare 9 different retraction configurations with one print. The tabs make it easy to tell different sections apart—no need to get out the calipers and measure distances!

The model has a very thin base, and is designed to use filament as efficiently as possible. It is optimized for 0.2 mm layer height, and prints in about 20 minutes.

The FreeCAD solid model is included, so you can make your own versions! Add more segments, move the towers further apart, etc. Or make the tabs stick really far out to make a truly evil temp tower...

Dimensions

Each segment is exactly 5 mm tall; with 9 segments per tower, both towers are 45 mm tall off the base. The base is exactly 0.6 mm tall. Each tab is intended to be on the first layer of each segment, so they are all exactly 0.2 mm tall, and spaced 5 mm apart center-to-center. The towers are 20 mm apart center-to-center, and 3 mm in diameter.

If printing with 0.2 mm layer height as recommended, each segment is exactly 25 layers (the base is 3 layers). So, the segments start on the following layers: 4, 29, 54, 79, 104, 129, 154, 179, and 204. The tabs are on these same layers, since they align with each segment's first layer.

Instructions

To use this test, you need to change the settings at different z-levels. To do this in Cura:

1. Set your desired baseline settings as usual. For instance, if you're going to vary the retraction distance, make sure to set your intended retraction speed etc.
2. From the menu bar, select Extensions > Post Processing > Modify G-Code
3. Add 9 instances of the "ChangeAtZ" script
4. For each script instance, set "Trigger" to "Layer No."
5. Set the "Change Layer" options to whichever layers each segment starts on. For 0.2 mm layer height only, see the layers in Dimensions above.
6. For each script instance (i.e. segment on the towers), set the configuration you want to test.

Tips

I recommend putting your "starting" value in the middle segment, then using the 4 above and 4 below to test in both directions (greater and lesser values).

If there are any stringy filament leftovers stuck to the extruder, clean them off first! They might get stuck to the tower and cause a false positive.