Update README.md

README.md

@@ -13,6 +13,7 @@ Fusion model:
  100% power, 500 frequency. 4 passes each piece. The material gets heated
  and need to take turns in cutting each piece. Had to do several tests to understan
  the settings of the laser cutter. While cutting, many 'angels'
- appear (flames).
+ appear (flames). Also, need to clean the lens
+ of the laser cutter several times in between jobs.
  The fumes are very toxic. I will try to replace some parts with acrylic.
   
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