# FDM 3D Printing Houston Post Processing A Technical Guide
Fused Deposition Modeling is an exceptional process for producing strong, functional parts with speed and efficiency. The additive, layer by layer nature of the technology, however, results in visible layer lines and a surface finish that may not be suitable for all applications. For engineers developing consumer facing products or components requiring a precise fit and finish, post processing is a critical step to bridge the gap between a raw print and a finished part.
While numerous finishing methods exist, three core techniques provide the foundation for most applications: sanding, priming, and tapping. Mastering these processes allows you to transform standard FDM parts into components with aesthetic appeal and expanded mechanical functionality.
## Foundational Sanding Techniques
The primary goal of sanding is to reduce or eliminate visible layer lines, creating a smooth, uniform surface. This is a manual, labor intensive process that requires patience and a systematic approach. Rushing the process will yield subpar results.
The key to effective sanding is grit progression. Begin with a lower grit sandpaper to quickly remove the peaks of the layer lines and level the surface. A 120 or 220 grit paper is a common starting point for raw prints. Work in small, circular motions to avoid creating flat spots or gouges in the part. Once the most prominent lines are gone, move to a higher grit paper, such as 400, to remove the scratches left by the previous step.
For a truly smooth finish, wet sanding is the preferred method. Applying a small amount of water to the part surface acts as a lubricant and helps carry away removed Simplify3D Materials Guide, preventing the sandpaper from becoming clogged. This technique, typically used with 400 grit and higher, produces a finer finish than dry sanding alone. Continue the progression through 600, 1000, and even 2000 grit for a surface that is nearly injection mold smooth. For small details and internal features, a set of needle files and flexible sanding sticks are invaluable tools.
## Priming for Paint and Finish
Sanding alone creates a smooth surface, but microscopic imperfections often remain. Priming serves two purposes: it fills these tiny pinholes and scratches, and it provides a uniform, tenacious base layer for paint. For FDM parts, a high build or filler primer is ideal, as its thicker consistency is designed to fill surface irregularities.
The process is iterative and requires a clean environment. After an initial sanding pass, clean the part thoroughly to remove all dust and debris. Apply a light, even coat of primer. Do not attempt to cover the part in a single heavy coat, as this can lead to drips, runs, and long curing times. Allow the primer to cure completely according to its specifications. Working in our 3D Printing Houston TX facility has taught us to be acutely aware of environmental conditions; high humidity can significantly extend primer curing times and affect the final finish.
Once cured, inspect the part under good lighting. The uniform color of the primer will reveal any remaining layer lines or imperfections. Wet sand the primed surface with a higher grit paper, such as 400 or 600 grit, until smooth. Clean the part again and apply another light coat of primer. This cycle of priming and sanding may need to be repeated two to three times to achieve a flawless, ready to paint surface.
## Creating Threads with Tapping
For mechanical assemblies, creating threaded holes is a common requirement. While threads can be modeled directly into a part, the resolution of FDM often produces weak and imprecise results, especially for smaller thread sizes. Tapping a printed hole with a standard metalworking tap is a far more reliable method for creating strong, accurate threads.
Success starts in the design phase. The diameter of the printed hole is the most critical variable. It must be precisely sized to accommodate the specific tap being used. If the hole is too small, the tap will induce significant stress, likely cracking the part. If it is too large, the threads will be weak and ill formed. We highly recommend printing a small test block with a range of hole diameters in 0.1mm or 0.005 inch increments to determine the optimal size for your material, printer, and specific tap.
When you are ready to tap, secure the part firmly. Use a standard tap and a tap wrench. Ensure the tap is perfectly perpendicular to the hole opening. Begin turning the tap slowly. The standard technique is to turn the tap half a turn forward, then a quarter turn back. This action breaks the cut chip of material and clears it from the flutes, preventing binding and material buildup. Do not apply excessive downward force; let the cutting edges of the tap do the work. The result will be clean, functional threads ready for assembly. Our large scale print farm in Houston regularly produces parts that later undergo tapping for complex engineering assemblies.
Ready to print your next part? Fixed price. 7 business day turnaround. Free manufacturability review. Visit www.splinearc.com or email Hello@splinearc.com.
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Related Services
- Spline Arc
- FDM 3D Printing Houston
- Custom Plastic Parts Houston
- CAD Design Services Houston
- Rapid Prototyping Houston