Frequently Asked Questions

location when the entire shell had been printed. These marks are
commonly referred to as blobs or zits. As you can imagine, it is
difficult to join two pieces of plastic together without leaving any
mark whatsoever, but there are several tools in Simplify3D that
can be used to minimize the appearance of these surface blemishes.
(1) Retraction and coasting settings
If you start to notice small defects on the surface of your print,
the best way to diagnose what is causing them is to watch closely
as each perimeter of your part is printed. Does the defect appear
the moment the extruder starts printing the perimeter? Or does it
only appear later when the perimeter is completed and the extruder
is coming to a stop? If the defect appears right away at the
beginning of the loop, then it’s possible your retraction settings
need to be adjusted slightly. Click on “Edit Process Settings” and
go to the Extruders tab. Right below the retraction distance, there
is a setting labeled “Extra Restart Distance.” This option
determines the difference between the retraction distance when the
extruder is stopping and the priming distance that is used when the
extruder is restarting. If you notice a surface defect right at the
beginning of the perimeter, then your extruder is likely priming
too much plastic. You can reduce the priming distance by entering
a negative value for the extra restart distance. For example, if your
retraction distance is 1.0mm, and the extra restart distance is -
0.2mm (note the negative sign), then each time your extruder stops,
it will retract 1.0mm of plastic. However, each time the extruder
has to start extruding again, it will only push 0.8mm of plastic
back into the nozzle. Adjust this setting until the defect no longer