Recently I glued together some laser cut pieces of Acrylic with patchy results. The bonding was good but the Acrylic cracked. Hundreds of tiny cracks all along the cut edge.
![IMG_0267](http://www.elektronaut.at/wp-content/uploads/2015/07/IMG_0267-300x267.jpg)
So, what does one dot o prevent this?
![IMG_0270](http://www.elektronaut.at/wp-content/uploads/2015/07/IMG_0270-300x235.jpg)
The manual states to temper pieces for 2 to 4 hrs at 70°C (≙158°F) to prevent stress cracks. I never assumed that cutting Acrylic with an laser cutter made the cutting edges prone for stress cracks and thought I was applying the glue wrong.
Since everyone told me that these cracks aren’t normal I tried this tempering stuff and put some test pieces for 30 minutes in an oven. Even this short tempering period reduced the amount of cracks by 100% :-). I don’t know if this short tempering time has negative long term effects. If crack form in the future I will let you know.
Long story short or TL;DR
When using a laser cutter to cut Acrylic temper them in an oven.
![IMG_0275](http://www.elektronaut.at/wp-content/uploads/2015/07/IMG_0275-300x182.jpg)