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First Layer Flow Rate
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In order to compensate for die swell of various materials, we would like a flow rate compensation setting for first layer only.

This setting will change the flow rate of the extruders for the first layer only. Upon second layer, it will return to flow rate as defined in the profile.

There is currently a post processing script (tweak at z) which has the same functionality.

Event Timeline

karrad created this task.Dec 8 2017, 2:16 PM

Just some background, since the description mentions the "tweak at z" plugin for this functionality....

At the tweak point, the plugin (v5.1) correctly issues M221 to change flow (i.e., "M221 S110" for 110%). Unfortunately, when the tweak ends -- it appears to always issue "M221 S-1.0000", rather than the correct flow value from the profile.

There is an active issue upstream for the poor "tweak at z" behavior:

victor_larchenko closed this task as Resolved.Dec 11 2017, 1:38 AM
karrad reopened this task as Open.Dec 11 2017, 12:22 PM

First layer compensation is added, and works. However, when starting layer 1 the flow rate automatically defaults back to 100% instead of what is defined in the profile:

to duplicate:

Load Polylite PLA standard profile > Change flow rate to 95% > Change flow additional multipler initial layer to 90% -> Slice gcode

You can see the change to 90% for layer 0
Upon starting layer one, it will default to M221 S100 instead of M221 S95

@victor_larchenko Can we also update the name of the setting to "Initial Layer Flow Rate" and the description to:

"Changes the flow rate for the first layer only. Used to compensate for filament die swell."

@karrad, engine don't change printer flow rate by default - standard "flow" setting changes E values. New setting changing printer flow rate, so it is a multiplier for old = if we want to change back to default multiplier after first layer it should be set to 100%

ScottWell1 added a comment.EditedDec 11 2017, 5:52 PM

@victor_larchenko @karrad

I pulled down 2.6.60 to test this. Works great! I foresee some people questioning the "multiplier" effect -- i.e., if "Flow" is 95% and I specify "First layer flow" at 110%, I actually get something like 105% of Esteps for first layer (i.e., 110% of 95% of Esteps value). But in practice, I agree with how Victor implemented it -- because having layer 0 flow be "relative" to the standard flow, as done with M221, is the best way to do this.

I suggest that the pop-up tip for "Initial Layer Flow Rate" include the string "Affected by: Flow", since it is a multiplier and changing "Flow" will also change the net effect of the "First layer flow" value.


@karrad, I've changed name and description, but we still need proper way to indicate that this setting is relative to basic flow.

@victor_larchenko Ahh thank you, that makes sense.

As for highlighting the relative nature, I like @ScottWell1 suggestion.

Lets add "Affected by: Flow" in the same format as other tool tips.

victor_larchenko closed this task as Resolved.Dec 14 2017, 3:49 AM