Printly Preflight beta

; how it works

How Printly checks a print.

Scroll through a guided preview of Printly checking a sample print file, then see the details of what it found.

; guided preview

Watch Printly check a print.

A recording of Printly with a sample file, a T-shaped test part. It plays as you scroll, forwards or backwards. This page is only a preview: it doesn't accept files.

  1. Start with a choice

    Printly opens with two options. Analyze G-code checks a print file for risks. The STL/3MF viewer only shows a 3D model; it doesn't check it.

    Printly's start screen with two cards, Analyze G-code and Open STL/3MF Viewer. The pointer rests on Analyze G-code.

  2. Open the print file

    Choose Analyze G-code, then drop in the file your slicer made. Here it is the sample Tshape.gcode.

    The sample file Tshape.gcode being dragged onto Printly's drop zone, which is highlighted.

  3. Watch it take shape

    Printly rebuilds the print from the file, layer by layer. The nozzle follows the file's own toolpaths. This is Printly's loading preview, not real print time.

    Printly's 3D view while it rebuilds the T-shaped part from its toolpaths, with a small nozzle at the top of the part printed so far.

  4. See what it flags

    Moving the layer slider to layer 251 shows the top bar printed over open air. Printly flags it in red as a possible risk.

    Printly's 3D view up to layer 251. The top bar of the T, printed over open air, is highlighted in red.

  5. Get a suggested next step

    Printly suggests what to check first: here, adding supports under the bridge.

    Printly's Next Step panel, highlighted: Bridge Sag, marked critical. The bridge is probably too long to print cleanly without support, and Printly suggests adding supports under it.

Recorded in Printly with a sample file. Waiting time is shortened, and the pointer is drawn in to show where each click happens.

; the result

What Printly found, and what changed.

The same T-shaped test part, in more detail. It is a different sample from the stand on the Home page.

  1. The overall assessment

    Printly gives the file an overall assessment with a confidence score. For this part: Don't Print, 29%, with bridge sag as the main risk.

    For experienced users: the G-code lines behind it
    Tshape.gcodelayer 251
    14743;LAYER_CHANGE
    14744;Z:40.2
    14745;HEIGHT:0.16
    14746;BEFORE_LAYER_CHANGE
    14874;TYPE:Bridge
    14875;WIDTH:0.412287
    14876G1 F1500
    14877G1 X106.032 Y134.018 E.48965
    14878G1 X106.41 Y134.018 E.00931
    14879G1 X106.41 Y114.315 E.48545
    14880G1 X106.787 Y114.315 E.00931
    14881G1 X106.787 Y134.018 E.48545
    14882G1 X107.165 Y134.018 E.00931

    Copied from the sample file. Red lines: the slicer's own ;TYPE:Bridge label and the long moves across the gap, from Y114.315 to Y134.018.

    Printly's assessment of the T-shaped part: Don't Print, 29% confidence, main risk Bridge Sag, with the suggestion to add supports under the bridge.
    T-shaped part, sliced without supports.

  2. The other possible risks

    After its first suggestion, Printly lists the other possible risks it found, most serious first: bed adhesion, tower stability and unsupported geometry.

    Printly's Next Step panel for the T-shaped part. First, Bridge Sag, marked critical, with the suggestion to add supports under the bridge. Then three other risks, each marked high: Bed Adhesion, Tower Stability and Unsupported Geometry.
    The first suggestion, then the other flagged risks.

  3. Re-slice and check again

    We turned on tree supports in the slicer and checked the new file.

    Printly's assessment of the file

    Don't Print 29% Print With Caution 73%

    Not a print result. This compares Printly's two assessments of the file. It does not show how the part actually printed.

    The same T-shaped part with tree supports, shown in blue, holding up both arms of the top bar.
    With tree supports, shown in blue.
    Printly's assessment of the supported file: Print With Caution, 73% confidence. Main risk Bridge Sag, with the guidance to check the support contact and top gap under the bridge.
    The new assessment now points at the support contact under the bridge.

; what it checks

What Printly looks for.

In every file, Printly checks for these common causes of failed prints.

  • Bridge sag

    Bridges that may be too long to print cleanly without support, with an estimate of how far they could sag.

  • Overhangs

    Areas that may droop because there is not enough material underneath them.

  • Bed adhesion

    A first layer with a small contact area, which may come loose from the bed.

  • Tall, thin parts

    An estimate of whether the nozzle could knock the part over during printing.

  • Supports and brims

    Recognises supports and brims in the file and takes them into account. Warns when supports are off but the part seems to need them.

  • Print facts

    The material and the slicer's own time estimate, read from the file. Layer count, size and an estimated weight, worked out from the toolpaths.

The T-shaped part in Toolpath Mode up to layer 251, showing the individual printed lines, including the lines across the unsupported top bar.
T-shaped part in Toolpath Mode, up to layer 251.

Three ways to look at a print

Clean Preview for the shape, Risk Overlay for the flagged areas and Toolpath Mode for the individual printed lines. Each works with the whole print, a single layer, or everything up to a layer.

Compatibility and limits

Works with
Sliced G-code files (.gcode): the file your slicer exports for your printer.
Tested most with
PLA, sliced in Flashforge's Flash Studio. Other slicers and materials are still being checked.
Model files
STL and 3MF files can be opened for a quick 3D look, without a print check.
Keep in mind
Printly only sees the file, not your printer, filament or room. Its results are guidance, not a guarantee.

Try Printly on your next print.

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