What is Post-Processing in 3D Printing?
Post-Processing Permutes Pre-Perfect Prints into Post-Perfect Parts
3D printing is a fun and exciting hobby to adopt! It can be a shock, however, to see your first prints and notice the effects of the 3D printing manufacturing process: visible layers of plastic, printing (mostly) in one color, strings and flashing from untidy nozzle pathways, or a surface finish that does not agree with your imagination. Post-Processing your parts after the print can help you achieve the manifestation of that vision of your part you hold in your mind's eye. Let's explore a brief overview of some post-processing techniques which exist for printed parts!
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| Sandpaper!, 1 |
Sanding:
Sanding with sandpaper or sanding sponges can abrade the outside shell of your print into a smooth surface. The process starts with by using a lower grit sandpaper until desired smoothness is obtained, then proceeding to a higher grit sandpaper to repeat the process. Continue graduating to high grit values until you achieve your final desired outcome. This technique will work better with plastics which are harder and less likely to melt at lower temperatures as sanding will generate heat. Parts printed with ABS filament are a good candidate for sanding. Sanding will, however, carry with it the potential to discolor your parts. Be prepared to paint your parts if a specific color is desired. Sanding will also affect the final dimensions of your part as you are abrading away material from your part when you sand. Sanding is also an effective preparation for your part to receive other forms of post-processing.
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| Painting Time!, 2 |
Painting:
Painting your parts is a great way to show off a chosen style for your parts. It is also the most sure-fire way to get the color results you want. Painting can also help to smooth the layers on the z-axis side of parts by filling in the small gaps between layers (though care must be taken, paint can also accentuate the visuals of layering). Acrylic paint is a common choice, but be sure to test your paint with your printing material first! Application of a thin, model primer or processing your parts by sanding before you paint is recommended. Painting may affect your part's final dimensions so be sure to consider your techniques to be used during design.
Fill-In:
Two-part epoxy resin may be used to either fill in the gaps of or completely resurface the layering found on the z-axis orientation of parts. Follow the guidelines for the proper use of the epoxy resin in question and be sure that the exothermic reactions that many epoxies produce are not of sufficient temperature to distort or warp your parts. Another method which may be used if your parts are made of ABS is to use a ABS slurry as a wet fill for resurfacing. ABS slurry can be made by combining ABS filament with Acetone until a paste is formed. Be very careful when working with acetone as it produces fumes, is flammable, and has the potential to distort or melt your part. Fill-in techniques may affect your part's final dimensions so be sure to consider your techniques to be used during design.
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| A jar of Acetone, be careful! 3 |
Outer Layer Chemical Resurfacing:
Much like how acetone may be used with ABS filament to make a slurry, Acetone vapor / fumes may be used to gently dissolve and displace the outside layer of an ABS print to result in a smooth uniform surface. A part may be placed in a container in a manner which leaves it offset from the floor of the container. The floor of the container would then be flooded with acetone which will quickly start to evaporate, producing the desired acetone vapor. The container may then be covered. Check on the part every few minutes until the desired outcome is achieved. Be sure to wear gloves, wash your part afterwards, and to perform this procedure in a well ventilated area.
Agglomerating:
Agglomerating is process of combining separate things into one whole thing. In the context of 3d printing it can be used to describe processes which combine parts of parts into one whole part. You may wish to do this if the final part is bigger than the print volumes found on printers available to them. Smaller pieces of a part may be printed and combined together. This can be done in several different ways. You can simply glue parts together using many different kinds of glue. Be sure to test for chemical compatibility using a small waste part or some filament which is the same as the parts to be glued together. Another technique which may be used with ABS prints specifically is cold-welding your parts together. The edges or surfaces of your separate parts which need to be be connected are brushed with acetone and fixed together firmly using a jig or other support rig. The acetone will melt the ABS plastic at the location of application and the resulting slurry will glue the parts together once the acetone is evaporated. You may also use mechanical fasteners using some traditional methods such as drilling holes to be used by threaded nuts and bolts.
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| An example of what support material looks like on a print! 4 |
Support Removal:
Support removal is a vitally important form of post processing if you have used support structures during your print. The support structures can be removed in several different ways. Be sure to take into account the type of material used for the support structures. The use of PVA or other dissolvable materials may be dissolved using the techniques recommended by the provider or manufacturer of the materials. Most other support materials may be cut or removed using mechanical means such as knives, saws, files, or picks.
Considerations During Design:
Before you begin your print, you should consider what qualities your final part should have.
Do you want the part to be shiny and smooth? To be vibrantly painted? To be resistant to wear and shock and weather? All of these qualities can be achieved by post processing, however you must be sure to consider than many processing techniques will affect the final dimensions of your part. Sanding and outer layer resurfacing will reduce your parts size, while fill-in techniques or painting will increase the size of your part. Print additional shell layers if you think you will be aggressive with sanding techniques. Print your parts slightly undersized or perhaps with fewer shells if you think you will be adding epoxy or paint and the fit of your part matters. If your parts don't have to interact with other parts the sizing matters much less. If your prints are too large for your printer and you are thinking of fixing smaller printed sections together to form your part consider the size allowances for your printer. You should also think very long about how best to segment your print so that you can have a strong and capable part in the end.
Do you want the part to be shiny and smooth? To be vibrantly painted? To be resistant to wear and shock and weather? All of these qualities can be achieved by post processing, however you must be sure to consider than many processing techniques will affect the final dimensions of your part. Sanding and outer layer resurfacing will reduce your parts size, while fill-in techniques or painting will increase the size of your part. Print additional shell layers if you think you will be aggressive with sanding techniques. Print your parts slightly undersized or perhaps with fewer shells if you think you will be adding epoxy or paint and the fit of your part matters. If your parts don't have to interact with other parts the sizing matters much less. If your prints are too large for your printer and you are thinking of fixing smaller printed sections together to form your part consider the size allowances for your printer. You should also think very long about how best to segment your print so that you can have a strong and capable part in the end.
Before we go:
We at the La Quinta Creation Station hope to show some small examples of some of these techniques in the upcoming weeks! Keep watching for more soon, and have a wonderful day!
Keep Makin' it happen,
William
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