TissueDB/Guides/From STL to PLA Print

3D Printing Guides · PLA

This guide explains how to prepare an existing model for printing with PLA filament: a solid strand of polylactic acid plastic used by a compatible filament-based 3D printer. It also explains what to give a printing service and what to check when the component is returned.

You do not need to design the model yourself. You do need the simulator's model files and printing requirements. Use this guide only when those instructions specify PLA filament. If the material or process is unknown, return to Confirm required process.

For a simulator that specifies ABS, use From an STL File to an ABS Print.

The worked example is the Tibial Shaft Transverse Fracture Simulator. Its two fragments have particular material, orientation and internal-structure requirements. Its source instructions also contain a sizing discrepancy and an infill-pattern compatibility issue, explained in Steps 5 and 6. Resolve applicable conflicts before exporting or printing; do not treat the example as a universal PLA recipe.

The four stages below are different. The drawings use generic shapes; they are not software screenshots, printer profiles or evidence of a successful print.

You will need a computer running a slicer compatible with the intended printer, access to that printer, the specified PLA filament, and the simulator and printer instructions.

Before operating the printer: use a suitable printing location with the ventilation or emission controls required by the equipment/material guidance and local workshop procedures. Do not assume PLA printing is emission-free. Read the instructions for hot surfaces, moving parts and material handling before starting.^[2] Follow Steps 1–9.

You do not need to install slicing software or configure the provider's printer.

1. Complete Steps 1 and 2 below.
2. Send the provider the original STL files, their versions, the simulator's printing instructions and the number of each component required.
3. Ask the provider to confirm that its equipment can meet the stated requirements, including any model-specific material, colour, size, orientation and internal structure. For the tibial example, flag the sizing and infill issues in Steps 5 and 6.
4. Resolve missing information or proposed substitutions with the simulator developer before production. The provider prepares the machine-specific file; do not assume a file prepared for another printer can be reused.
5. Ask the provider to identify the material used and report any deviations. When the parts arrive, continue with Step 9's component checks.

Expected result: both parties know which files, quantities and requirements apply, and unresolved differences have been identified before printing.

If this is not possible: pause the order and ask the developer to clarify the unresolved requirement. A provider's ability to print the shape does not by itself establish suitability for the simulator.

For the tibial example, download both files from the developer's 2022 file set: Download Model 1 — proximal fragment, 25 June 2022 (STL) and Download Model 2 — distal fragment, 19 May 2022 (STL).^[3]

An STL contains shape coordinates but does not specify their units. The size displayed after import therefore needs checking; a filename or a displayed scale of 100% is not enough.^[4]

Save the files in a folder you can find again. Keep the original filenames so the model numbers and versions remain identifiable. Do not mix these files with a different revision's settings without confirming that they belong together.

Expected result: you have two downloaded STL files, one for each listed fragment, identifiable by model number and date.

If this is not what you see: check that the download completed and that you saved the STL rather than a webpage. If a link fails, return to the developer's download table or ask the developer for the specified revision.

Open the tibial print-preparation instructions alongside this guide. For another simulator, use that simulator's own instructions instead.

Identify four things before changing software settings:

• Equipment and material: required printing process, printer compatibility and filament.
• Size and orientation: the intended dimensions and which face should rest on the printer's build plate, the surface on which it prints.
• Print structure: required settings for the outside walls, the interior and any temporary printing structures.
• Acceptance checks: dimensions, assembly checks or other criteria the developer supplies for the finished part.

Keep the source link and file versions with your notes. Mark any missing or conflicting requirement rather than filling it with a guess. A default is the software's starting value; it is not necessarily the simulator developer's requirement.

Expected result: you can distinguish the model's explicit requirements from software defaults and identify anything that needs clarification.

If you cannot: ask the developer about the particular missing item. Include the model filename and relevant source instruction, rather than asking only which settings are “best”.

Using a printing service? Once the requirements are clear, return to the service handoff.

The tibial instructions name UltiMaker Cura, or Cura LulzBot Edition for the appropriate LulzBot workflow.^[3] Obtain the software through its official provider. The following control names refer to UltiMaker Cura; their position can vary by version.

1. Open the slicer and add or select the exact printer model. Do not select a similar-looking machine as a substitute.
2. In Cura's Printer selection panel, confirm which printer is active.
3. In the Configuration panel, match the nozzle or print core to the one actually installed. The nozzle is the tip that deposits material; the configured outlet diameter must match the installed one.
4. Confirm the printer's usable build volume: the width, depth and height within which it can print. Use its documentation or ask the operator.^[5]

A profile is a saved group of settings. Selecting a printer or material profile supplies a starting configuration; the model-specific settings still need to be applied.

Expected result: the selected printer and nozzle match the physical machine, and you know its usable printing space.

If they do not match or are unknown: stop setup and consult the operator or manufacturer. Do not use an arbitrary printer profile to make the model fit.

1. Check the filament label against the model's required material and the printer's compatibility information.
2. For these tibial fragments, use the specified white PLA; the developer also calls for freshly opened filament. Follow its material-condition guidance, not colour alone.^[3]
3. Select the matching material entry in the slicer. The tibial instructions permit Generic PLA if the filament brand is not listed, but this does not apply the model-specific structure settings or establish that every PLA product is equivalent.

Expected result: the actual filament and the selected material profile agree, and the printer can use that filament.

If the label, material or compatibility is unclear: ask the provider or manufacturer before proceeding. Do not replace the required material simply because another filament is available.

In Cura, choose File → Open File(s)..., select an STL and open it. The model should appear in the three-dimensional work area.^[6] Select the model and confirm its identity.

The following illustrations use generic blocks. They are not either tibial STL or a slicer screenshot. The patterned strip marks the same intended base wherever that base is visible.

Action: For the tibial fragments, place the marked base on the build plate; the fracture end faces upward. Rotate only as needed to reach that orientation.

Action: Read the displayed width, depth and height, including their units. Compare them with the source. Change scale only when the model's requirements permit it. Any permitted scaling of these paired fragments must use the same factor for both. Record the factor and resulting dimensions.^[3]

Action: Inspect the base and its placement on the build plate.

Action: Compare the oriented model's width, depth and height with the selected printer's usable printing space. Include the space needed for the base and any required adhesion features.

The developer's model overview reports heights at 100% scale of 202.2127 mm for Model 1 and 202.2275 mm for Model 2. Elsewhere it says a 200 mm build height is sufficient at 100%, while also giving a 200 mm UltiMaker S3 example at 95%. These published figures are inconsistent; they are not a confirmed fit rule for your printer.^[7]

Do not automatically choose 100% or 95%. Check the imported dimensions after orientation, the available height and any permitted paired reduction. If you cannot reconcile them, ask the developer and print provider before exporting. Do not shrink either fragment independently merely to clear a fit warning.

Expected result: the intended fragment has its marked base on the build plate, its dimensions have been reconciled with the requirements, and both models use the same agreed scale. Each fits within the usable printing space.

If it does not: recheck the selected printer, displayed units, dimensions and orientation. In Cura, a grey-striped overlay indicates a model outside the printable region. A solid colour is not proof that all requirements are correct; colours can reflect the selected material.^[1]

First distinguish the four features below. These generic drawings do not show either tibial STL and do not prescribe a thickness, pattern or density. For the linked tibial fragments, supports are disabled and the fracture ends remain open (Top Layers = 0).

Build-plate adhesion features are different: a brim is an attached border at the base; a raft is a printed platform beneath the part; a skirt is a separate outline around the part. Follow the model-specific adhesion instruction below.

In Cura, open the Print settings panel and select Custom. Use the setting-name filter to find each required control.^[8]

Compatibility check — read before selecting infill. The developer names Tri-Hexagon or 3D Honeycomb. UltiMaker's current guidance says to avoid self-intersecting patterns including Tri-Hexagon on the UltiMaker S6, S8 and Factor Series because they can cause collisions, vibration and printer damage. If this affects your setup, stop and seek clarification from the developer and printer manufacturer; do not print through the conflict or silently select another pattern. The current Cura Honeycomb entry is described as a 2D pattern, not confirmation of equivalence to the developer's 3D Honeycomb.^[9]

The following values summarise the developer's instructions for the two linked 2022 fragments. They are model-specific overrides, not a complete printer profile.^[3]

Source settings for these tibial fragments only

Setting	Developer's instruction and check
Wall Thickness	6.2 mm.
Top Layers	0. The fracture-end interior is intentionally exposed.
Bottom Layers	Retain a nonzero default. The source does not give a fixed count.
Infill Density	15%. This is a slicer setting, not a claim about the whole part's porosity.
Infill Pattern	Tri-Hexagon or 3D Honeycomb in the source. Resolve the compatibility warning above before selecting a pattern.
Supports	Disabled for these fragments.
Build Plate Adhesion Type	Skirt, or an appropriate brim following build-plate guidance. No raft.
Layer height	The source says “0.15 mm to 0.3 mm or less”. Clarify how this wording applies to the intended printer/profile; do not substitute an invented fixed value.
Speed and other defaults	The source limits speed to the unmodified PLA defaults and retains other stated top/bottom defaults. It does not provide a complete set of numeric values.

Defaults depend on the printer, profile and software version. Record those details and resolve unclear or incompatible values with the developer and printer operator; a newer profile's defaults are not evidence of what the original instructions used. Do not copy these settings to an unrelated simulator.

Expected result: the visible controls match the applicable source requirements, with the sizing, pattern and default-dependent questions resolved before producing a print file.

If a control is missing, differently named or unavailable: check the Custom view and setting filter. If you cannot establish an equivalent control or safe compatible configuration, ask the developer or manufacturer. Do not assume a similarly named option is equivalent.

Select Slice and wait for processing to finish. Open Preview. This shows planned printing paths, not just the outside surface of the STL.^[10]

Use the drawings below as reminders while you inspect your actual preview. They are not slicer screenshots, paths generated from these STLs, or evidence that a model has passed inspection.

Expected result: the intended fragment appears throughout the layer preview, including its required walls, interior and base. Intentional openings remain open. There are no unresolved warnings or unexplained deviations from the requirements. Repeat the check for the other fragment.

If the preview is wrong: return to Step 5 for size or orientation, or Step 6 for structure settings, then slice again. If the issue remains, pause and share the filename, printer model, warning text and preview screenshot with the developer or operator. Do not change the design merely to make the warning disappear.

1. Reconfirm the intended printer and configuration. Use the slicer's save/export option and the transfer method supported by that printer.^[1]
2. Save the generated print file with a name that distinguishes the model and intended machine. Some printers use G-code, a form of machine instructions; other workflows use different formats.
3. Keep the original STL and a record of the settings separately. If you also save a slicer project for later editing, do not confuse it with the printer-ready output.^[11]

Expected result: you can identify the output file, its target printer and the format/transfer method required by the printer's instructions. It is not simply another copy of the STL.

If the printer rejects it or the target is unclear: return to the selected printer and export configuration. Do not fix the problem by renaming a file extension or by borrowing a print file made for a different machine.

Prepare and operate the printer according to its manufacturer's instructions, including hot surfaces, moving parts and material handling. Filament printing can release airborne particles and chemicals; use the specified ventilation or emission controls rather than assuming PLA needs none.^[2] Allow the part to cool and remove it using the manufacturer's method. Printing-service users start with the inspection below when their parts arrive.

1. Confirm that each required component is present and identifiable. For the tibial example, check the two different fragments and their base markings.
2. Inspect for unintended cracks, incomplete regions, separation between layers or deformation. Distinguish these defects from the example's intentionally open fracture ends and visible infill.
3. Check dimensions and any assembly or other acceptance checks specified by the simulator developer. Confirm any agreed scaling and ask the provider about unreported differences.
4. Keep a damaged or nonconforming part out of the build while you resolve the problem. Use the printer manufacturer's troubleshooting for printing faults and the simulator developer for model requirements.

Expected result: you have the required components and have completed the checks the developer specifies, with any deviations recorded and resolved before assembly or use.

If acceptance criteria are missing: ask the developer what to check. Appearance and a completed print do not establish the required tactile or mechanical properties, or validate the simulator's training performance. Do not invent a tolerance or performance test to fill that gap.

• A file will not open: confirm the download completed and that the file is the intended STL. Download again from the source if necessary; do not substitute another model revision unnoticed.
• The model is unexpectedly small or large: check units, displayed dimensions and scale before changing size. An STL is unitless.
• The model does not fit: check the selected printer, usable build volume and orientation. For the tibial pair, resolve the Step 5 sizing issue before agreeing a common scale.
• A setting is missing or conflicts with safety guidance: pause and ask about that specific setting, printer and software version. Do not bypass the conflict with a guessed replacement.
• The preview seems to have holes: compare with the intended openings and infill, and check preview visibility. Unexpected missing structure needs investigation; intentional spaces do not need filling.
• The printed part is damaged or incomplete: do not proceed to simulator assembly. Investigate the printing fault and recheck the model requirements before attempting a replacement.

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