Bottom surface flow (beta)

Bottom surface flow puts a little less plastic into the first layer’s bottom surface, so parts grip the plate less and release more easily. Use it when parts still stick too hard after the cooldown. It is still in beta: switch on Beta features in the app footer to see it.

Beta

Off by default. Pro and Business accounts switch it on with the Beta features switch at the bottom of the FarmLoop app. It changes the G-code that gets printed, so watch the first loop after you turn it on.

Where to find it

1. Switch on Beta features in the footer of the FarmLoop app.
2. In the Detachment tuning step, go to Tuning Parameters. Bottom Surface Flow sits under Z Offset, with a BETA badge.
3. Switch it on and set the target: 0.90 to 1.00, in 0.01 steps. It starts at 0.97.

It works on Stage 1 and Stage 2, on every printer.

Why less plastic helps

The bottom surface is the solid layer that sits on the plate. A few percent more plastic there presses more of it into the plate’s texture, and that is grip. Farms report that 1.05 sticks hard and 1.00 or a little below pops off after the cooldown.

The first layer on a textured plate, seen in cross-section. Orange marks where the plastic touches the plate. Exaggerated, not to scale.

What changes and what stays

• Changed: the printing moves of the bottom surface on layer 1. Bambu Studio and OrcaSlicer mark them as “Bottom surface”, PrusaSlicer as “Solid infill” on the first layer.
• Unchanged: the walls, also on layer 1, the supports, every layer from layer 2 up, and the retractions and wipes.
• Every loop copy in the file gets the same change.

Which number your file starts from

Slicer	Records the bottom surface flow?	What your target does	Example at 0.97
OrcaSlicer, ElegooSlicer, Snapmaker Orca	Yes (bottom_solid_infill_flow_ratio)	Rescales from the sliced value to your target	Sliced at 1.05: 7.6% less plastic (×0.924)
Bambu Studio, PrusaSlicer	No, so the file counts as 1.00	Works as a plain factor	3% less plastic (×0.970)

The app shows what it will do under the slider, for example: “Bambu Studio does not record a bottom surface flow, so the sliced file counts as 1.00. At 0.97 the bottom surface gets 3% less plastic (x0.970).”

An OrcaSlicer file sliced below your target gets more plastic, not less: sliced at 0.95, a target of 0.97 adds 2.1%.

How to tune it

1. 1

   Start at 0.97 and process the file.

2. 2

   Print one loop and watch the first layer. It should still hold while the part prints.

3. 3

   Check the release after the cooldown.

4. 4

   Go lower in 0.01 steps if parts still stick. On a textured plate stay closer to 1.00: textured plates need more squish than smooth ones.

5. 5

   Go back up if parts come loose during the print, or the bottom shows gaps between the lines.

One lever among several

The Z offset moves the whole first layer, walls included. Bottom surface flow only changes how much plastic goes into the bottom surface. If parts still stick, work through Parts won’t detach: Z offset, cooldown temperature, bottom layers and the plate itself.

Over the Processing API

Business accounts send the target as bottomSurfaceFlow, from 0.90 to 1.00. See Processing API: extra tuning tools.

Related

• Parts won’t detach
• Z offset
• Choosing a build plate