3D Printing Feed (Small-Scale) Calculator FAQ
Answers to common questions about FDM filament feed rate, volumetric flow, slicer inputs, and hot-end capacity.
Use these answers to understand the calculator inputs, interpret its flow results, and recognize factors that can make actual FDM extrusion behavior differ from a steady-state estimate.
General calculator questions
Basic information about what the calculator estimates and when to use it.
What does the 3D Printing Feed calculator calculate?
It estimates required filament feed speed, volumetric flow, filament feed per minute, and the percentage of an entered hot-end flow capacity used by a planned FDM profile.
Is filament feed rate the same as print speed?
No. Print speed is the nozzle's movement speed during extrusion, while filament feed rate is the linear speed at which the extruder pushes filament into the hot end.
What units does the calculator use?
Line width, layer height, and filament diameter use millimetres; print and feed speed use mm/s; volumetric flow uses mm³/s; and capacity use is shown as a percentage.
Is this calculator for resin printing?
No. It is designed for filament-based FDM or FFF printing, where a solid filament is fed into a heated nozzle.
Inputs and profile settings
Questions about entering slicer settings and measured filament dimensions.
Should line width match nozzle diameter?
Not necessarily. Enter the line width specified in the slicer. It is often near or slightly wider than nozzle diameter, depending on the profile.
Which print speed should I enter?
Use the speed of the actively extruding feature you want to assess, such as infill, outer wall, inner wall, or top surface. Do not use travel speed.
What flow multiplier should I use?
Use the extrusion-flow setting for the profile being assessed. A nominal profile commonly uses 100%, while a calibrated profile may use another value.
Why measure filament diameter?
A measured diameter can be more representative of the spool than the nominal label value. Diameter affects calculated linear feed speed because it determines filament area.
Volumetric flow and capacity
Questions about interpreting hot-end demand and maximum-flow comparisons.
What is volumetric flow in FDM printing?
It is the volume of plastic the nozzle must deliver per second. Higher layer heights, wider lines, faster extrusion moves, and higher flow multipliers all increase it.
What does printer flow capacity used mean?
It is required volumetric flow divided by the maximum volumetric flow you entered, expressed as a percentage.
What if the result is above 100% capacity?
The selected settings demand more flow than the entered limit. In practice this can increase the risk of under-extrusion or inconsistent extrusion if the limit is accurate.
How can I lower volumetric-flow demand?
Reducing active print speed, line width, layer height, or flow multiplier lowers the calculation. The most appropriate change depends on the print goal and profile.
Can a larger nozzle increase flow capability?
It may support different throughput behavior, but practical flow still depends on the hot end, heater, filament, temperature, nozzle geometry, and print conditions.
Accuracy and real-world behavior
Factors that are outside the calculator's steady-state model.
Does the calculator include acceleration and corners?
No. It estimates steady demand at the entered extrusion speed. Actual movement changes speed through acceleration, deceleration, and corners.
Does pressure advance change the calculated volumetric flow?
The calculator does not model pressure advance. That feature can alter short-term extrusion behavior around speed changes, while the calculation estimates steady-state demand.
Why might a print under-extrude below the calculated limit?
Possible causes include inaccurate flow-limit input, low temperature, partial nozzle blockage, filament variation, extruder grip issues, cooling effects, or a profile-specific setting.
Is the bead cross-section exactly rectangular?
No. Deposited molten filament has a rounded and compressed shape. The rectangle model is a simple, useful approximation for estimating flow.
What is volumetric flow in FDM printing?
It is the volume of plastic the nozzle must deliver per second. Higher layer heights, wider lines, faster extrusion moves, and higher flow multipliers all increase it.
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