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Important: Always be careful when focusing thick material, not to allow material to collide with the lens
housing. This can cause serious damage to the laser machine.
Lens Replacement
Lenses are one of the few parts of a laser machine that need regular maintenance, primarily regular clean-
ing. Lens cleaning is simple if done often, difficult or not possible if rarely done.
The lens is small, about 20 mm across, with 2 distinct sides, one flat and one convex or curved out.
When
reinstalling, the curved side always faces the laser path, away from the working platform.
As illustrated
above, the lens assembly consists of 2 main parts, the lens tube (also known as the lens housing) and noz-
zle, then 3 parts inside the lens tube. The lens, washer and slotted ring nut. To remove lens for replacement
or cleaning, loosen the friction set screw on the main lens housing holding the lens tube in place. After
loosening set screw the lens tube should slide out of the housing. Separate the lens tube from the nozzle
like the illustration shown in the illustration above. Your laser tool box came with a tool for removing the
slotted ring nut. The tool looks more like a scraper than a screw driver. Its width is designed to fit inside the
lens tube and fill the slots. Be careful not to let the blade tip slip and scratch the lens. Once the slotted ring
is out, the rubber washer will keep the lens pressed against the lens tube. Using a pencil with eraser, insert
the eraser end into the laser tube and push out the lens. Both lens and washer will fall out the large end.
At this point the lens can be replaced or cleaned. Different size lens can be inserted as well, just be aware
that a 4” lens has a different focus point than a 2” lens. The beam width increases with focal length and
may require a nozzle with a larger opening. Handle the lens carefully, using acetone or lens cleaner/wipes
to clean the flat side. Make sure to place the flat side down towards the working platform when reassem-
bling, curved side always faces the laser beam. Lens first, washer and then ring nut. Don’t over tighten
ring nut, just snug it up against the washer, and then a quarter turn more. Burned lenses are a common
