Seam concealment
If this button is down, seam concealment technique will be applied to looped extrusions.
SplineTravel's seam concealment (or seam blending) is a technique for spreading out the [seam](SplineTravel glossary#seam) (the place where perimeter loop ends meet). This is done by doing retraction and unretraction while tracing the loop.
Seam concealment involves the following steps:
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Remove unretraction from the travel move preceding the perimeter.
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Instead of starting to extrude the perimeter as usual, start tracing the perimeter and unretract.
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As unretract is complete, extrude the full the perimeter.
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Continue tracing the loop while retracting.
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When the required retract amount is reached, start the travel move (with retraction withdrawn from the move).
So, the perimeter loop is overdone, and if the loop is small, or retract speed is low, or print speed is high, the perimeter may be looped two and more times in a row.
Retract (under "Travel moves and retraction")
Amount to retract is set in "Travel moves and retraction" setting group. There is no special retract amount for seam-concealment so far.
This parameter sets how close start and end points of an extrusion loop need to be to consider it a loop.
If the extrusion is a loop, seam concealment is going to be applied if it's enabled, and retraction/unretraction will be withdrawn from travel moves and done while tracing the loop. If the extrusion is not a loop, seam concealment will not do anything, and retraction/unretraction will be done as part of travel.
Setting this to a value of about one extrusion width should be good enough for most cases.
This sets the speed of retraction and unretraction that is being done when tracing the extrusion loop. This setting doesn't affect the speed of retraction when traveling.
The higher the speed, the less "overlooping" will happen, and the more confined will be the seam. However, high E speeds may cause printer to stop moving because of [E](SplineTravel glossary#e) [jerk](SplineTravel glossary#jerk) violation, so keeping it below E jerk is a good idea.