It took a long while, but a few weeks ago I finally removed the last bugs out of my force-extension machine’s code, and testing could commence. I focussed initially on creep, a phenomenon that occurs in the thermoplastics that we 3D print with. This phenomenon has not been investigated very much yet, and I hope to change that.

If you want to get the full story, please see the video below. Further down I will put the main results and links to the raw data. If you have any suggestions, questions, or comments, please leave them under the Youtube video, or e-mail them to

Test procedure

The machine puts the sample under a predetermined amount of load, and then stops. Over the time force recorded by the machine will decrease due to creep. I investigated PLA using stresses up to 57.5 megapascals. Samples were left for 4 hours after initial loading.

Stress versus time for initial stresses of 5-55 megapascals. Note that creep becomes much more severe at very high stress levels.

You can find all of the data, processed and raw, and the python code used for analysis here.

First creep tests completed