Neptune Fixturing Guide

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Primary fixturing goals

1. Remove all secondary motion: Ensure the part is perfectly immobilized. Any movement beyond the intended stage rotation will cause blur and compromise the accuracy of the reconstruction
2. Part isolation: Elevate the part from the turntable to ensure capture of the intended geometry. This prevents high-density stage components from interfering with the reconstruction and ensures the integrity of your scan
3. Artifact mitigation: Strategically orient the part to minimize artifacts during reconstruction. Proper alignment ensures the X-ray beam has the most efficient path through the material, resulting in superior scan quality

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Fixturing orientation & strategy

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General recommendations

• Minimize the X-ray path: Aim to orient your part so that the X-rays pass through the least amount of dense material possible. A shorter path length increases the number of photons reaching the detector, which significantly improves the quality of your final reconstruction.
• Tilt your part: Flat surfaces that sit perfectly horizontal (parallel to the X-ray beam) are prone to cone-beam artifacts. These appear as streaks or “blurring” that can obscure critical data. Tilting your part, even slightly (5 though 30 degrees) can help greatly mitigate these artifacts

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Advanced scenarios and trade-offs

• Focused area of interest: If your inspection is focused on one specific internal component, prioritize the orientation that provides the clearest view of that area. In these cases, you might tolerate cone-beam artifacts on parts of the scan if it means reducing metal artifacts near your target zone.
• Multi-material complexity (plastic vs. metal): Multi-material parts containing both low-density plastics and high-density metals are highly prone to metal artifacts. In these cases, it can be beneficial to choose a non-intuitive orientation where a longer overall X-ray path avoids passing through dense metallic components. This may result in a cleaner reconstruction of the surrounding plastic features.
• Tilting versus magnification: Tilting is essential for reducing artifacts, but it creates a larger rotational “swing room” that often forces the part further from the source, limiting your total magnification. This creates a fundamental trade-off between maximum resolution (high proximity) and image clarity.

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Fixture basics

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Choosing fixturing materials

1. Density and segmentation: Choose fixture materials that are distinguishably lower density than your scan object. This will make it easier to separate fixtures from parts using Voyager’s attenuation sliders. Low-density materials (foams, plastics) are preferred for widespread compatibility and easy data segmentation. Denser materials can be used for fixturing as long as they remain clearly distinguishable from the part in the scan. For example, when scanning an aluminum part, a moderately dense plastic fixture is still easy to filter out. Keep in mind that higher-density fixtures are less versatile and may be suitable for a narrower range of parts.
2. Rigidity and stability: In addition, fixtures should be rigid and stable. A rigid fixture will not flex or compress under the part’s weight, and a stable setup keeps the part fully constrained so it does not rock or slide during the scan. Minimizing secondary motion helps produce sharper reconstructions, more accurate dimensions, and more consistent results from scan to scan.

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Recommended fixturing materials

• Floral foam: useful for quick, custom press-fits
• Styrofoam: very low density and widely available
• PLA / ABS / PETG: 3D-printable plastics for repeatable, custom fixtures
• Carbon fiber: low density with high stiffness for robust fixtures
• Tape: fast, simple restraint for various parts
• Velcro straps: reusable, adjustable way to secure parts
• Rubber bands: versatile and reusable restraint for solid parts

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Lumafield standard fixturing accessories

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Breadboard turntable

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Angled Foam Fixtures

• Specifications: Available in three sizes (60mm, 100mm, and 175mm in diameter)
• Setup: Utilize the integrated pins to ensure rapid, error-proof assembly. The weighted metal base provides a stable foundation for this fixture. Use Velcro straps and elastic bands to securely restrain parts.

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Lollipops

• Specifications: Lollipops are available in two bases sizes (100mm and 170mm tall); standoffs (1” and 3” tall) can be used for height adjustment
• Setup: For maximum stability, install three Lollipops into the Breadboard turntable to support your part. Use standoffs as needed for height adjustment and tape to help stabilize your part. Make sure to tighten the assembly by holding the carbon fiber shaft to avoid damaging the foam interface.

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Floral foam and Foam Retention Spikes

• Related resources: See the Resources section to download CAD of the Foam Retention Spikes (STEP & STL)
• Setup: Install three or more Foam Retention Spikes into an appropriately-sized Breadboard turntable with an adjustable wrench. Once installed, press a block of green floral foam onto the spikes until secure. You can then carve or press-fit your part directly into the foam.

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Custom fixtures

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Lumafield’s modular system

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Resources

• QS-60 Collet Plate Drawing (PDF) - Essential dimensions for custom baseplates

• Download: Breadboard Turntable Baseplate (STEP)
• Download: Foam Retention Spikes (STEP & STL)

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Custom solutions and support