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Sanding 3d printed objects


Ultimate Guide to Sanding 3D Prints

Sanding 3D printed models can be a great way to eliminate layer lines in preparation for painting, silicone molding, or vacuum forming.

In this “how to”, we will show you the best practices associated with sanding your 3D prints.

Working time will vary depending on your model. The process shown took us about 3 hours from start to finish.

SUPPLIES

Sandpaper (80, 120, 240, 220, 1000, 1500 grit)

Handheld electric sander

X-acto Knife

Needlenose pliers

Flush cutters

Chisels

Bin to hold water

Respiratory Mask

Eye protection

Gloves

Need some of these products? We've curated an Amazon wish list for you.

STEP 1: PREPARE & PRINT MODEL

Consider: Print settings, print orientation, number of build plates. Surfaces printed in the Z axis will have the smoothest surface finish.

Surfaces printed in the Z axis will have the smoothest surface finish.

Supplies used: Needle-nose pliers or flush cutters and chisels

A. Remove the print from the build plate

B. Remove rafts and support material from the model

When removing supports using pliers or clippers, be sure to wear eye protection.

C. Remove large pieces of support first, and then approach smaller pieces and fine details

D. Clean the edges and seams of your model to ensure better alignment of pieces

If you plan to glue your model, take care not to remove too much material around seams or joining surfaces, or you will need to use filler later on.

The 2021 Guide to 3D Printing Materials

Learn about polymers, composites, and metals all available for 3D Printing!

Supplies used: Electric sander and 80 grit sandpaper

A. Begin sanding with coarse (80 grit) sandpaper

Be sure to wear eye protection and a respiratory mask as sanding will release particulates.

B. When sanding with 80 grit sandpaper, the goal is to remove any leftover blemishes from raft or support material, and create an even surface that you will later refine. This process will remove the most amount of material and take the most time.

C. In early stages of sanding you will notice that your model surface that was once fairly shiny will become dull and rough and change in color. The shine will return as you move to higher sanding grits.

Be sure not to sand in one place for too long as heat generated from friction could melt the PLA.

D. To save some time you can use an electric sander or multitool. If using a multi tool, be sure to choose a low setting to avoid overheating/melting the PLA.

E. After each sanding stage, clean the model of any dust and inspect for a uniform surface finish

Move on to sanding with higher grits when all large to medium sized imperfections or blemishes have been removed.

STEP 4: SAND WITH MEDIUM GRIT SANDPAPER (DRY)

Supplies used: Electric sander and 120 & 240 grit sandpaper

A: Sand with 120 grit sandpaper (dry)

B: Sand with 240 grit sandpaper (dry)

C: If you notice large imperfections that you have missed, return to a lower sanding grit to refine those areas

As you move up through various finer grits, sanding should require less time. You will also notice that the model’s texture becomes more refined and much smoother.

Supplies used: 1000 grit sandpaper, plastic bin and water

When your model’s surface is even and refined it is time to wet sand the model using fine grit sandpaper. This process will not remove much material, but will do the most to polish its surface.

A: Submerge the model in a tub filled half way with water

Take care around fine features, round surfaces, and other small or difficult to reach places.

B. Using 1000 grit sandpaper, sand the model until it is completely smooth to the touch

 

C. Dry the model and inspect for a uniform surface finish

If you have properly sanded your model, its surface should now be even, blemish free, and glass-like to the touch.

Here you can see the difference between the unfinished surface and final sanded part.

Visit one of our other applications pages for tips on how to take your print even further.

We recommend that you visit our pages on:

Gluing
Painting
Silicone Molding

Last but not least, remember to share your work with us on Thingiverse and social media @MakerBot.

We can’t wait to see what you make!

Hair Dryer Shell
Ferro
10/2/2015
https://grabcad.com/library/hair-dryer-shell-1

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Ultimate Guide to Finishing 3D Printed Parts

Time to read: 13 min

The purpose of this article is to detail the different finishing methods for FDM and PolyJet 3D printed parts and the techniques/tips that can elevate the look and feel of your prototypes.

A simple Apple Watch stand design will be utilized as a case study. This stand is a model with pockets and internal and external features that needs to be surface finished to a standard that complements the shiny exterior of an Apple Watch put on it.

Here’s a quick overview of the main points this article covers:

  • PLA: If you’re working with a tight budget then PLA is going to be your best material choice; the results aren’t as polished but the price is cheapest.
  • ABS: If your budget is moderate then go with ABS. It’s not as cheap as PLA but still at a low price point and the material is more reliable than PLA.
  • VeroBlack or VeroWhite: For the highest quality parts go with VeroBlack/VeroWhite. This will give you the best dimensional accuracy and best overall polished look.

Overview of Post-Processing

The 3d printing post-processing needed for the watch stand parts involves a combination of repairing and preparing the print for post-processing, sanding, and painting.

The finished sample 3D printed parts with all three materials should be smooth, matte black surfaces. Inherent to the 3D printing process, with every print are unique challenges and considerations to arrive at the best finish possible. Although there are ways to mitigate the challenges, experience in 3D printing goes a long way.

The print settings process for each material is detailed separately and a summation of the results may be found in the conclusion of this article.

ABS (Printed on a Dimension Elite)

The Dimension Elite prints are smooth, clean, and ready to sand out of the NaOH bath.

There are, however, clear stepping lines between the printed layers. If we don’t remove these stepping lines, they’ll show up in the final paint coat which will ruin our smooth finish. Thankfully, removing these will be easy thanks to ABS’s high melting point and easy sandability.

Materials Needed

The materials we’ll be using:

  • Sandpaper (grits 100 to 600)
  • Medium, fine, and extra-fine sanding sponges
  • XTC-3D brush-on coating (As an alternative, Bondo putty is a common solution to fill holes in parts. We chose XTC-3D for its viscosity, sandability, and ability to penetrate small perforations, which makes it desirable over Bondo putty)
  • Razor blade
  • Foam brush, mixing cups and popsicle sticks
  • Sandable Krylon Primer
  • Montana Acrylic Primer in Shock Black
  • Matte Acrylic Varnish

Sanding

Sanding the ABS print is simple and straightforward. First start with 100 – 200 grit sandpaper to remove stepping lines and then gradually increase up to 600 grit to achieve a smooth finish without sanding lines.

Pro Tip: Sand in small circular movements evenly across the surface of the part. Avoid sanding in one direction only, especially in the direction of the stepping lines to prevent striations or “trenches” in the print.

Beware that ABS is very easy to sand, so be careful not to overdo it. Removing as little as .010” can be enough to completely remove any stepping layers and oversanding can compromise critical dimensions.

After sanding the parts, some holes are revealed on our part left by an incomplete layer around the letters DIM. These holes can perforate through the finished paint coat to create ugly sinkholes, so we need to find a solution.

As you can see in the Catalyst tray to the right, there are large holes between the DIM and the edge of the part. Moving the DIM up in our Solidworks model would solve this, but for now we’ll have to find a way to fill these holes with a sandable filler.

Repairing the Incomplete Layer

We’re going to use a thin, sandable epoxy called XTC-3D to fill the tiny holes and crevices in our print. XTC-3D is cheap (a 24 oz bottle costs about $25), quick, thin, and effective. Note that a small amount goes a long way (within the 10 minute pot life).

Pro Tip: Be sure to maintain a weight ratio of 100 Part A to 42 Part B. Mix thoroughly for one minute and coat your part within the 10 minute pot life. For more details, check Smooth-On’s technical bulletin here, and a great instructional example here.

Before applying the XTC-3D, wash the part with soap and dry with compressed air to ensure your part is thoroughly clean and free of any oils or sanding dust. Also make sure to wear gloves so as not to get any hand oils or sweat on your part.

Fill in holes or gaps in your print with a very thin (1/64”) coat; a thin layer of XTC-3D will level itself out. We used a razor blade to scrape excess XTC-3D into the unwanted holes and gaps, making sure to avoid any areas we didn’t want filled (like the letters DIM).

Allow the XTC-3D sufficient time to become tack-free dry (approximately 2 hours). Now we’re ready to continue sanding away at the excess XTC-3D layer with 300 to 600 grit to reveal the repaired surface.

Then, after another thorough wash, we’re ready to begin preparing our repaired surfaces for painting.

Priming and Painting

Painting 3D printed parts is a vast world of acrylics, enamels, sprays, and airbrushes.

In this example, we’ll be using Montana spray can paints to follow a relatively straight forward process: prime, dry, paint, dry, varnish, dry.

Standard spray painting principles apply:

  1. First make sure your surface is oil-free, dust-free and hole-free
  2. Shake your cans for at least two minutes prior to painting
  3. Ensure your cap is clean to prevent drips
  4. Be aware of how the paint is accumulating on the part and look for any pooling or dripping
  5. Paint in many light coats rather than fewer heavy coats; this is especially important for 3D printed parts with internal and obscured geometries
  6. Paint in controlled, well-ventilated and well-lit areas

The Dimension prints started with very obvious stepping between layers. If you’ve sanded properly up until now to create as smooth a surface as possible, these layers shouldn’t show up in your final paint finish.

The Final Result

The finished ABS part is matte black and smooth to the touch with very little evidence of layering in most surfaces. A few important results to note here:

  • Sharp internal pockets are tough to sand. After about 30 minutes of sanding, we still had a hard time removing all the layering and the stepping shows up even after priming, painting, and varnishing the print.
  • Because we had to remove more surfaces from the sanding, there is some sacrifice in regards to the final geometry of the part.
  • Filling the incomplete layer with a thin coat of XTC-3D worked very well; those holes are invisible in the final paint layer.

VeroBlack (Printed on an Objet30)

Thanks to .0011” resolution, the Objet30 prints have some stepping between layers, but nowhere near as obvious as in our FDM prints.

The Objet30 prints come out of the printer with a thick layer of support structure material so before we can begin finishing our VeroBlack part, we’ll need to remove this support structure and the residue it leaves behind.

VeroBlack 3D Printed Part Materials Needed

The materials needed for post-3D printing finishing:

  1. Sandpaper (grits 100 to 600)
  2. Medium, fine, and Extra fine Sanding Sponges
  3. Sandable Krylon Primer
  4. Montana Acrylic Primer in Shock Black
  5. Matte Acrylic Varnish

VeroBlack 3D Printed Part Sanding

Start with 100 grit sandpaper to wet sand the residue and gradually move to wet sand with 300 grit sandpaper; the residue will fall off in small soft white chunks. This is the hardest part of the VeroBlack finishing process and it took us about 30 to 40 minutes to remove all the residual layer.

After removing the residual layer by wet sanding utilizing 300 grit sandpaper, the surface of the part will begin to feel smooth. If you rub the part with your fingernail, you’ll feel it’s harder and more plastic-like beneath the gummy residual coat. Continue wet sanding through to 600 fine grit sandpaper until the part is fully smooth.

Pro Tip: Water breaks up the residue, so wet sanding is a highly effective method to get a smooth, residue-free, paintable, and homogenous surface.

Thoroughly clean your part with soap and water before you move on to the next step to remove any additional residue. Again, we recommend using compressed air to dry the part and clear any accumulated dust.

Beware that VeroBlack is like ABS: very easy to sand, so be careful not to overdo it. Once you break through the residual layer, the actual VeroBlack will sand very easily. Removing as little as .005” can be enough to completely remove any stepping layers. Be careful as oversanding can compromise critical dimensions.

VeroBlack 3D Printed Part Priming and Painting

Next, we’re going to paint the VeroBlack part just as we did the ABS part: using Montana spray can paint with the following process: prime, dry, paint, dry, varnish, dry.

Standard spray-painting principles apply:

  1. First make sure you have a good surface quality which is oil-free, dust-free and hole-free
  2. Shake each paint can for at least two minutes prior to painting
  3. Ensure your cap is clean to prevent drips
  4. Be aware of how the paint is accumulating on the part and look for any pooling or dripping
  5. Paint in many light coats rather than fewer heavy coats; this is especially important for 3D printed parts with internal and obscured geometries
  6. Only paint in controlled, well-ventilated, and well-lit areas

VeroBlack 3D Printed Part Final Results

The finished VeroBlack part is matte black and smooth to the touch. A couple points to note here:

  • Some of the internal corners were not sanded enough to remove the residue, so you can see how the paint powdered up in these areas. This will likely result in peeling paint over time.
  • Although very little stepping is visible on the part, you can see slight evidence of it here. This part could have probably used 30 more minutes of thorough sanding.

PLA (Printed on a 5th gen. Replicator)

Now for the dreaded PLA, a notoriously difficult material to finish. But with some tricks and patience, it too can join ABS and VeroBlack in the ranks of matte black glory!

This Replicator print came off the plate with severe striations: see the parallel grooves in the layers of the part above. This could be a result of machine quality, but for now we’ll just have to find a way to maneuver these striations to a smooth part.

Sanding PLA is difficult, in part because of how soft and gummy it becomes if you try to sand too aggressively or quickly, so we’ll explore options on how to smooth 3d prints with minimal effort and abrasion.

PLA 3D Printed Part Sanding

If you choose to sand the PLA directly, the process is straightforward. Note: PLA acetone smoothing is not advisable. PLA smoothing is not as forgiving as ABS when it comes to sanding and abrasion, so you will likely spend more time removing the stepping between layers, especially with the severe striations in a print like ours.

Begin with a low (100 – 200) grit sandpaper, sanding away at the bumpy striations and any raft or support material (aluminum foil) left behind. Particularly in the case of MakerBot support, it’s easiest to remove them with a flush cutter or pair of pliers and brush them with a rotary multi-tool first before sanding away at them.

Depending on the size and geometry of your part, you’ll likely be stuck in the 100 – 300 grit sandpaper range for a while to smooth out striations and pesky support structure remnants.

Once layering and striations are less prevalent, move through finer grits (400 – 600) sandpaper to achieve a shiny surface ready for priming and painting.

Pro Tip: Patience is key when sanding PLA. Turn on a movie or your favorite show, but don’t zone out! Sand in small circles evenly across the surface of the part. If you’re using a sanding multi tool on PLA, be careful not to overheat/melt your 3D printed part. 

An alternative method to sanding PLA prints directly is smoothing the PLA print with the XTC-3D first and then sand on top of the coating.

PLA 3D Printed Part Finishing

We’re going to use XTC-3D to create a smooth, sandable, paintable layer of epoxy clear coat glossy finish around our PLA print.

Before applying XTC-3D, ensure that your part is thoroughly clean, free of any oils and sanding dust (sensing a pattern yet?). Wash the part with soap and dry with compressed air to clear any dust. Again make sure to wear gloves to protect both your part and your hands.

Brush on the XTC-3D in a thin (1/64”) coat; as long as the coat is thin enough, it will level itself out. Between coats, leave 1.5 hours for the XTC-3D to dry.

It may be difficult to coat an entire part at once, so don’t be afraid to do it in sections, making sure to keep overlapping to a minimum between sections. Wait 90 minutes between first and second coats and after you’ve finished wait 2 hours to allow the shiny surface to become tack-free.

With striations as severe as ours, it will take multiple coats to get a smooth uniform surface, so patience is key. Remember that multiple thin glossy finish coats will level better than thick coats.

Pro Tip: Internal pockets are susceptible to pooling so be careful to suck up or remove any pooling that occurs before the XTC-3D begins to dry (that’s what we’re doing in the left picture above).

Beware that XTC-3D may compromise critical dimensions, but applying thin glossy finish coats will allow you to minimize the additional material.

After the XTC-3D layer has hardened (two hours after application of the last coat) it should be ready for sanding. Follow basic sanding guidelines, starting with 300 grit sandpaper (thanks to the smoothness of the XTC-3D) and sanding in small circular movements to even the surface. Any wavy patterns may require a coarser grit sandpaper to remove.

The sandpaper will scratch up the XTC-3D coat; focus on getting a level surface, moving through to 600 grit sandpaper.

After you’ve finished sanding 3D prints, make sure to thoroughly clean your part with soap and water and then dry using compressed air before moving on to the next step.‍

PLA 3D Printed Part Priming and Painting

Painting PLA parts follows the same process as the ABS and VeroBlack parts: prime, dry, paint, dry, varnish, dry.

Standard spray painting principles apply:

  1. Make sure your surface is oil-free, dust-free and hole-free
  2. Shake your cans for at least two minutes prior to painting
  3. Ensure your cap is clean to prevent drips
  4. Be aware of how the paint is accumulating on the part and look for any pooling or dripping
  5. Paint in many light coats rather than fewer heavy coats; this is especially important for 3D printed parts with internal and obscured geometries
  6. Paint in controlled, well-ventilated and well-lit areas

PLA 3D Printed Part Final Results

The XTC-3D coated PLA part is matte, black, and has a smooth surface to the touch with a few problems:

  • Although the XTC-3D has worked well to smooth the part and make sanding quicker and easier, it has left pooling in the internal pocket that has shown through the paint finish.
  • Striations are still visible on the part. 30 more minutes of sanding 3D prints could have prevented these from showing through the final paint finish.

Results and Closing Thoughts

After finishing all three parts to a smooth, matte black finish, let’s take a look at the differences in process, time, materials and finish.

Differences in Process
ABS (Dimension Elite)
  • Sand from 100 to 600 grit
  • Repair holes with XTC-3D (may not apply to your part)
  • Sand away XTC-3D with 300 to 600 grit
  • Prime, Paint, Varnish
VeroBlack (Objet30)
  • Sand from 100 to 600 grit
  • Prime, Paint, Varnish
PLA (Replicator 5th gen.)
  • Coat in 1 to 3 layers of XTC-3D (depending on how bad the striations on your print are)
  • Sand away XTC-3D with 100 to 600 grit
  • Prime, Paint, Varnish

Differences in Time

The part that took the longest to finish was PLA due to the XTC-3D coating time. Even without XTC-3D, however, PLA typically takes longer to sand than ABS or VeroBlack.

In our example, the VeroBlack was ultimately faster to finish since we repaired our ABS print with XTC-3D and stepping between layers was not as significant in the VeroBlack print.

All things considered, VeroBlack was the quickest to get to a smooth, matte black finish.

Pro Tip: If you’re in a rush to get from printer to photoshoot, pick the Dimension Elite or Objet30. Especially in models with overhangs and significant amounts of support material, the Dimension Elite and Objet30 both have support material that is quickly removable via dissolution, whereas the PLA support on a Replicator can significantly increase the time required to get to a smooth surface part.

Differences in Cost and Materials

It’s important to consider the amount of time it will take to finish your model as well as the overall look and dimension when considering the price.

PLA is the cheapest out of the three, at $20 per part, followed by ABS at $55, and VeroBlack at $110. In our opinion, VeroBlack is the best bang for your buck since it’s the shortest to surface finish and will give you the most accurate model.

Comparison of the Final Results

At first glance, all three models may look very similar, but there are a few key differences in the final finish.

Both the ABS and the PLA finished prints have evidence of stepping between layers that is visible in the final paint coat. The VeroBlack print requires much less effort to remove these steps, which ultimately are not as obvious in the final paint coat.

Although the ABS and the VeroBlack finished prints have very similar surface finishes, more material (approximately .020”) was lost in the sanding process for the ABS to remove stepping between layers. In contrast, the VeroBlack print required less sanding, so the final object dimensions are closer to the original design intent.

Individual Summary of Each Part

VeroBlack: High layer resolution (. 0011”) means little sanding is required to get a smooth, paintable part. Critical dimensions don’t need to be compromised to get a smooth surface quality part and no repairs are needed for fine detailed features.

ABS: Parts are easy to sand, but small fine detailed features may require repairing and careful sanding to remove stepping between layers. Once this stepping is removed, painting is straightforward.

PLA: The cheapest option, but also has the potential to be the most difficult to finish, depending on support structures and quality of the print. May require significant sanding and repairing via XTC-3D or Bondo filler.

Browse our website to learn more about our capabilities, such as 3D Printing and CNC Machining.

Quick Facts: 

  1. Finishing a 3D printed part often involves a combination of the following processes: smoother application, sanding, polishing, cleaning and painting. The process is unique to the material type.  
  2. A smooth finish with 3D printing is achievable but, post-processing will greatly improve the smoothness of parts. 
  3. Epoxy resins are an excellent choice for sealing PLA printed parts. 
  4. Acetone smoothing is not recommended for PLA prints.
  5. In general, IPA or rubbing alcohol will not dissolve PLA but there are some varieties that may be IPA soluble. Consult your filament material datasheet or technical datasheet for more information.
  6. PLA may be smoothed without sanding by dipping it or spraying it with a coating.
  7. ABS is tougher and lighter than PLA which is stronger and stiffer. Both have their ideal applications, but PLA is typically considered a hobby material whereas ABS is ideal for prototyping.

Plastic processing for 3D printer. Plastic post-processing after 3D printing ABS, PLA, Nylon, Petg

Contents:

  1. Post-processing of FDM parts
  2. Remove supports
  3. Removal of soluble supports when printing with a 3D printer with two extruders
  4. Sanding plastic 3D printed products
  5. Application of Acetone in ABS plastic processing
  6. Filling irregularities in ABS plastics
  7. Polishing ABS/PLA
  8. Priming and painting 3D printed products
  9. Acetone baths for ABS products
  10. Chemical solvent baths
  11. Using epoxy to finish prints

Hello everyone, Friends! With you 3DTool!

With the FDM 3D printing , you can quickly and economically produce plastic parts of any geometric shape. Finished parts show visually the lines of the layers they were printed on, making post-processing an important consideration if a smooth surface is required. Some post-processing techniques can also increase the strength of finished products by helping to reduce their anisotropic properties.
This article will discuss the most common post-processing techniques in FDM 3D printing .

Catalog of FDM 3D printers

Post-processing of FDM parts

This picture above (from left to right) shows the post-processed parts FDM :

  1. gap filling
  2. raw
  3. sanded
  4. polished
  5. painted
  6. epoxy coated

Remove supports

Support removal is typically the first step in post-processing for any 3D printing technologies if the part requires support for precision manufacturing. Supports can usually be divided into 2 categories: standard and instant .
Unlike other post-processing methods discussed in this article, support removal is a requirement and does not result in improved surface quality.
Removing supports mechanically is necessary when printing with a 3D printer with a single extruder (for example, PICASO Designer X, Hercules 2018, Zenit, Prusa i3 Steel Bizon) When using 3D printers with two extruders, as a rule, the supporting part of the product is made of special soluble materials.

Catalog of 3D printers with two extruders

Left to right. Original printing with support, poor support removal and quality support removal.

Tools and materials you will need for this job:

  1. Pliers
  2. Set with small tools (eg watchmaker's set).

Support Removal Process: The support material can usually be removed from the finished model without much effort. Cleaning of the substrate material in hard-to-reach places (for example, in holes) can be done using an awl and pliers. Properly positioned support structures and proper print orientation can greatly reduce the impact of the support material on the aesthetics of the final result.

Plus

  • The overall geometry of the part does not change
  • Fast on time

Cons

  • Does not remove visible layer lines, streaks or spots on print surface
  • If support structures leave excess material or marks behind, the accuracy and appearance of the part will be reduced

Soluble support removal when printing with a 3D printer with two extruders

As we said earlier, the removal of supports printed from soluble materials is done differently than manually, mechanically, so the use of 2 or more extruder printers is preferable. (e.g. PICASO Designer X PRO, Raise3D PRO2)

Catalog of 3D printers with two extruders

Tools and materials you will need for this job:

  1. Solvent safe container
  2. Thinner
  3. Ultrasonic cleaner (optional)

Process : the final model is placed in a bath with the appropriate solvent (for example, for PVA plastic it will be ordinary water, for material HIPS it will be D-limonene ) until the support material dissolves. Support is usually printed with:

  1. HIPS (in conjunction with ABS )
  2. PVA (in conjunction with PLA )

Glass storage containers such as jars are excellent receptacles for diluting limonene. For dissolution in water, any non-porous container will do. For prints using HIPS/ABS bath with a 1:1 ratio of limonene to isopropyl alcohol works very well for quick support removal. Many other auxiliary materials such as PVA (used with PLA ) are water soluble.

Helpful Hint: Speed ​​up the dissolution time of the support material by using an ultrasonic bath and changing the solution as soon as it becomes saturated with plastic dissolved in itself. Using a warm (not hot) solvent will also speed up the dissolution time if you don't have an ultrasonic cleaner available.

Catalog of ultrasonic baths

Pros

  • Great for complex geometries where standard support removal would be impossible without damaging the base model.
  • The result is a smooth surface where the support structure is in contact with the base piece.

Cons

  • Improper dissolution of the material can lead to discoloration and deformation of the entire part.
  • Does not remove visible layer lines, streaks or spots on part surface
  • May cause small spots or holes in the final print if soluble material gets on the object during printing

Sanding plastic 3D printed products

Sanded brown ABS plastic part

Tools and materials you will need for this job:

  1. Sandpaper up to grit 1000
  2. Rags
  3. Toothbrush
  4. Soap
  5. Face mask

Sanding process: After the supports have been removed or dissolved, sanding can be performed to smooth the part and remove any visible stains or traces of the supports. The initial grit size of the sandpaper depends on the layer height and print quality.
For layers with a height of 0.2 mm or less, or if there are no spots left on the part after printing, sanding can be started with a paper grain of - 150.
If there are obvious spots or the object was printed at a layer height of 0.3 mm or more, start sanding with 100 grit paper.

purity. The print should be cleaned with a toothbrush in soapy water and then with a rag, between sanding gradations to prevent the accumulation of dust and " sintering ". Your FDM parts can be sanded down to 5000 grit to achieve a shiny part surface.

Helpful Hint:
Always sand in small circular motions evenly over the entire surface of the part. Of course, it is more convenient to sand perpendicular or even parallel to the print layers, but this can lead to indentations in the model. If the part becomes discolored or if there are many small scratches after sanding, you can use a blow dryer. With it, you gently heat the part, thereby softening the surface a little and visible unnecessary defects will weaken or disappear altogether.

Pros

  • With this method, you get an extremely smooth surface
  • This method facilitates additional post-processing (such as painting, polishing, or epoxy coating)

Cons

  • Not recommended for thin wall prints as this may damage part
  • Difficult for surfaces with difficult geometries and fine details
  • May affect overall print accuracy if sanding is too aggressive and too much material is removed

Acetone for ABS plastics

Two white printed halves made of ABS bonded with plastic diluted in acetone.

Tools and materials you will need for this job:

  • Acetone
  • Cotton buds or brush

Machining process: When the size of the finished part exceeds the maximum size of the 3D printer's camera, the model often has to be broken into smaller parts and reassembled later by gluing. For PLA and other materials, bonding can be done using the appropriate adhesive (selection of adhesive will depend on the plastic) . For ABS plastic, multi-piece assemblies can be glued with acetone. The mating surfaces should be lightly moistened with acetone and held firmly together or, if possible, clamped until most of the acetone has evaporated. At this point, the two parts of your model will stick together.

Helpful Hint: increasing the contact area with acetone will increase the strength of the joint. This can be done by including block connections in the design.

Pros

  • Acetone will not discolor the part surface like other adhesives
  • After drying, the seam will exhibit ABS properties, making further processing easier and more uniform

Cons

  • The bond formed by this cold welding is not as strong as a solid impression
  • Excessive use of acetone can lead to aggressive dissolution of the part and adversely affect the final result and tolerances

Filling irregularities in ABS plastics

The gray ABS model had voids after sanding. The surface became smooth.

Tools and materials you will need:

  1. Epoxy resin (for small voids only)
  2. Automotive Putty (large voids and joints)
  3. ABS plastic and acetone (for small voids only and for ABS parts only)

Process: After sanding or removing soluble backings, gaps often appear in the print. During printing, gaps are sometimes formed, and often this pattern is unavoidable. Small gaps and voids can be easily filled with epoxy and no further treatment is required. Large gaps, or gouges, left from attaching model assembly parts can be successfully filled with automotive putty, which will require additional sanding after drying.
The putty gives excellent results and can be easily sanded and painted after it has fully cured. The connection will be strong, and will not weaken the plastic. Conversely, autofiller parts tend to be stronger than native plastic.

ABS print gaps can also be filled by making a slurry of ABS filament and acetone ( ABS juice or ABS juice ) that chemically reacts with the part and penetrates any surface voids. A ratio of 1 to 2 between ABS and acetone is recommended. This method will not significantly affect the cleanliness of the surface around the gap if properly applied.

Tip : If gaps are visible on FDM parts before sanding, fill them with epoxy and then sand once until dry. This will greatly reduce the overall time required to achieve a smooth surface.

Pros

  1. Epoxies are easy to sand and prime, making the surface easy to paint
  2. ABS juice will be the same color as your part, as long as you use the same filament by color and manufacturer. Therefore, there will be no discoloration of the surface

Cons

  1. Auto putty or other polyester epoxy will dry opaque resulting in discolored spots on print
  2. Requires additional sanding to achieve uniform coverage
  3. May affect overall print accuracy if sanding is too aggressive and too much material is removed

ABS and PLA polishing

Catalog of ABS plastics

Catalog of PLA plastics

Tools and supplies you will need

  1. Polish
  2. Sandpaper
  3. Nonwoven wipe
  4. Toothbrush
  5. Microfibre cloth or polishing pad

Process: Plastic polish can be applied after sanding the surface to give standard filament products such as ABS and PLA a glossy finish. After the part has been sanded to 1000 grit, wipe off any excess dust from the Non-woven » cloth, then clean it in a bath of warm water with a toothbrush.
Allow the piece to dry completely and buff it with a buffing pad, or by hand with a microfiber cloth and a jewelry polish designed specifically for plastic and synthetics that provides a long lasting shine.
Other plastic polishes, such as car headlight polishes, work on the same principle, but some may contain chemicals that can damage the original material.

Helpful Hint: For polishing small parts, attach the polishing pad to the Variable Speed ​​Drill (or other rotating tool such as a drill) . Bench grinders equipped with a polishing wheel can be used for larger, stronger prints, but don't polish too long in the same place. This can cause the plastic to melt due to friction.

Pros

  • Polishing is applied without the use of any solvents, which can deform the part and change the accuracy tolerances.
  • When properly ground and polished, the part will give the impression of a mirror finish, imitating plastic injection molding
  • Plastic polish and cleaner is very economical, making this method quite profitable for a quality finish

Cons

  • The part must be carefully sanded before polishing if a mirror finish is required. This may affect tolerances
  • Primer/paint may not adhere to surface after polishing and you will need additional products

Priming and painting 3D printed products

White PLA part spray painted gray

Tools and supplies you will need:

  • Nonwoven wipe
  • Toothbrush
  • Sandpaper
  • Aerosol Acrylic Primer
  • Polishing agents
  • Masking tape (only if using multiple colors)
  • Gloves and petal mask

Finishing process: after the part is properly sanded (up to 500 grit sandpaper is required at this stage) , the print can be primed. The primer should be applied in two coats using an aerosol can.
An aerosol primer designed for painting models will provide an even coverage and be thin enough not to darken the part before painting.
A thick primer, such as one available at the hardware store, may stick together and require more sanding.
Apply the first coat in short, quick strokes at a distance of about 15 - 20 cm from the part to avoid the formation of a thick layer of primer. Let the primer dry and sand down any imperfections with 9 grit sandpaper.0031 500. Apply the final coat of primer with light, quick strokes.

Once the primer is complete, painting can begin. Painting can be done with acrylic paints and artist's brushes, but using an airbrush or spray can give a smoother surface.
Hardware store spray paint tends to be thicker and harder to control, so it's best to use paints made specifically for painting models.
The primed surface should be sanded and polished (sanding and polishing sticks used in nail salons are ideal for this application) and then cleaned with a non-woven cloth.
Paint over the model using very light layers; the first few layers will look translucent. Once the paint has formed an opaque coat of (usually after 2-4 coats) , allow the model to dry for 30 minutes to allow the paint to set. Carefully polish the paint layer with nail sticks.

Multi-colour models can be painted with masking tape. Once all layers of paint are ready, remove the tape and buff the paint using polish paper. Polishing paper such as 3M or Zona can be purchased in a variety of grit sizes. You can buy it in a pack in many online stores. It will give the paint a shine that cannot be achieved in any other way.

Helpful Hint: Do not shake the can when using spray paint! The goal is to mix the pigment or primer, shaking the propellants will cause bubbles to form in the aerosol. Instead, rotate the jar for 2-3 minutes. The stirring ball should roll, not rattle.

Pros

  • Professional results with attention to detail
  • Excellent appearance of the final product, regardless of the material/color in which the object was originally printed

Cons

  • Paint and primer will increase the volume of the model, which will change the tolerances and can cause problems if the part is part of the assembly
  • Buying a high quality spray paint or airbrush is not cheap

Acetone baths for ABS products

Smoothed black model of a petal with a spherical surface made of ABS plastic after an acetone bath.

Tools and materials you will need:

  1. Non-woven cloth
  2. Sealed container
  3. Thinner
  4. Paper towels
  5. Aluminum foil (or other solvent resistant material)
  6. Face mask and chemical resistant gloves

Process: line the chosen container with paper towels along the bottom and, if possible, up the sides. It is very important that the steam does not disturb the chamber itself. The chamber may be sealed.
It is recommended to use glass and metal containers.
Pour in enough solvent to dampen but not drown the paper towels. This will also help them stick to the side walls of the container.
Acetone is well known for its ability to smooth out ABS parts. For PLA, smoothing is possible with various solvents, they work well, but as a rule, with PLA, it is more difficult to get a smooth surface, unlike ABS.

IMPORTANT! When working with any solvent, please follow the safety regulations for the chemical and always follow the appropriate safety precautions !

A small "raft" of aluminum foil or other solvent-resistant material should be placed in the middle of a lined paper towel container.
Next, place your part on this raft (either side selected as the bottom on the raft) and close the lid of the container.
Steam polishing can vary in duration, so check the print periodically. Heat can be used to increase polishing speed, but care must be taken to prevent the buildup of potentially explosive fumes.

When removing the part from the chamber, try not to touch it at all, leaving it on the raft and removing it from the container. Any points of contact with the part will generate surface defects because the outer shell will be half dissolved. Allow parts to dry completely before use.

NOTE . Many aerosol and/or spray solvents are flammable/explosive and solvent vapors can be harmful to human health. Be especially careful when heating solvents and always work in a well ventilated area.

Pros

  • Smooths out many small spots and reduces layer lines present in the print without any additional work
  • Creates a very smooth "shell" around part
  • A very fast method that can be implemented with improvised means

Cons

  • Doesn't "heal" gaps or completely mask layer height
  • The dithering process "dissolves" the outer shell of the print, and therefore the tolerances are greatly affected
  • Negatively affects print strength due to changes in material properties

Chemical solvent baths

Tools and supplies you will need:

  1. Solvent safe container
  2. Thinner
  3. Hook or small screw
  4. Wire
  5. Drying rod or stand
  6. Face mask and chemical resistant gloves

Process: Make sure the container you are using is wide enough and deep enough to hold the part and solvent. Fill the container with the appropriate amount of solvent, taking care to minimize splashing. As with steam smoothing, acetone should be used to dip the ABS.
PLA is sufficiently resistant to solvents, so it may take several passes to achieve the desired result.

Prepare the part for dipping by screwing an eye hook or small screw into an inconspicuous surface of the print. Pass the wire through the eye of the hook or around the screw so you can lower your piece into the wire bath. If the wire is too thin, you won't be able to submerge the part in the solvent.

After the part is prepared, quickly immerse the entire object in the solvent for no more than a few seconds using wire. Pull out the print and attach it to a wire over a dryer rod or rack to allow the solvent to completely evaporate from the surface. The part should be gently shaken after you remove it to facilitate drying and avoid solvent build-up in depressions on the surface.

Helpful Hint: If the part has an opaque whitish color after drying, it can be hung over a solvent bath for a while so that the evaporating vapors slightly dissolve the surface. This will restore the color of the print and provide a glossy outer layer.

Pros

  • Print surface smoothes much faster than steam polishing
  • Produces much less fumes than other solvent polishing methods and is safer

Cons

  • Very aggressively smoothes the surface of the part, so the tolerances deviate very much from the specified
  • Immersion too long can lead to complete deformation of the part and a significant change in material properties

Using epoxy to finish prints

The part is sanded and coated with epoxy resin.

Tools and materials you will need:

  1. Two-component epoxy (such as XTC-3D)
  2. Foam applicator
  3. Brushes
  4. Mixing container
  5. Sandpaper 1000 grit or higher

Process : After the print has been sanded (sanding first will give better end results) , completely clean it with a non-woven cloth.
Mix the correct ratio of resin and hardener as directed in the resin instructions. Make no mistake about the proportions. Epoxies are exothermic when mixed, so glass containers and containers composed of low melting point materials should be avoided.
Containers specifically designed for mixing epoxy resins are recommended. The wrong ratio will lengthen the drying time and the epoxy may never be able to fully cure, resulting in a disastrous and sticky part.

Mix resin and hardener thoroughly according to instructions. Stir gently to minimize air bubbles. The faster the epoxy dries, the better. Most epoxies have a working dry time of only 10-15 minutes, so do your post-processing in the proper order.

Apply the first coat of epoxy using a foam applicator and try to minimize resin buildup on recessed surfaces or other details of the print. Once your part is sufficiently covered with resin, allow it to fully cure according to the manufacturer's instructions. One coat may be enough to smooth the detail, but for optimum appearance, the print should be lightly sanded with fine sandpaper (1 000 grit or higher) . Remove dust with a non-woven cloth and apply a second coat of epoxy in the same manner.

Pros

  • A very thin coat of epoxy will not significantly affect part tolerances (unless the part has been sanded first)
  • Resin provides an outer protective sheath around the part

Cons

  • The layer lines will still be visible, they are under the "smooth" shell
  • Applying too much epoxy can cause surface dripping and over-smoothing of print details


Tools and supplies you will need:

  • Electroplating solution. It can be prepared by mixing a metal salt with acid and water, but if the proportions are not accurate, it will be difficult to get a professional result. Buying a ready-made solution guarantees that there are no problems with plating.
  • Sacrificial anode. The anode material must match the metal of the plating solution, so if copper sulfate is used in the solution, then a copper anode should be used. You can use any item made of metal plating (copper wire, for example), or you can purchase a thin strip of metal plating that is made specifically for electroplating.
  • Conductive paint or acetone and graphite. The print surface must be conductive for coating, which can be achieved with conductive paint or a 1:1 solution of graphite and acetone. Conductive ink will work on any printed material, but a solution of acetone and graphite will only work on ABS.
  • Power Rectifier - A battery can be used instead of a rectifier, but a battery is not as efficient and will not deliver results as quickly and consistently as a rectifier. A rectifier is also a safer option. It can simply be turned off to stop the current flow during electroplating.
  • Conductive screw or eyelet
  • Non-conductive vessel
  • Lead set
  • Non-conductive gloves and goggles.

Electrophoresis solutions are acids and can cause eye damage if splashed, so appropriate goggles are required. Also, these solutions can irritate the skin and conduct a charge when used. Therefore, non-conductive gloves should always be used.

Process: metal plating can be electroplated at home or in a professional workshop. Proper plating requires a deep knowledge of materials, and what you can do at home has certain limitations compared to what can be done in a professional workshop.
For a better finish and a wider range of plating options, including chrome plating, a workshop would be the best option. For clarity, the copper plating process will be described below.

At home, galvanization can be done using copper or nickel plate. It is imperative that the surface of the print to be processed is as smooth as possible before coating; any unevenness and visible lines of the layers will start to stand out after coating.
Prepare a cleaned and sanded print. By coating the plastic with a thin layer of high quality conductive paint or a solution of acetone and graphite (if made of ABS) . Allow the conductive coating to dry completely and sand if necessary to ensure a smooth finish. It is extremely important to minimize contact with the print or wear gloves as the sebum on your fingers will interfere with the coating process.

Insert a screw or hook with an eye into an inconspicuous surface of the part, similar to dipping in solvent.
Attach to one of the rectifier leads. This will serve as the cathode. The connection must be made to the negative terminal of the rectifier. Connect the copper anode to the positive terminal of the rectifier using the second power wire and fill the container with enough electroplating solution so that the imprint and the copper anode are completely hidden. Turn on the power rectifier. After the rectifier is turned on, make sure that the part does not touch the anode in any way.

IMPORTANT! Be very careful at this stage. Once the part is lowered into the bath and the system is energized, any contact with the solution, anode or cathode may result in personal injury !

Set the power supply rectifier to 1-3 volts. After that, the metallization process will begin until the part is completely covered with metal. Voltage may be increased to reduce coating time, but should not exceed 5 volts. Simply turn off the straightener and remove the print after a satisfactory finish has been applied. Dry the print with microfiber towels. Coat the part with a special varnish for metal after drying. This will protect it from corrosion.

Pros

  • The metal shell increases the strength of the plastic part, which greatly expands the possibilities of its application and use
  • The outer metal coating is very thin so if properly applied, tolerances of 9 can be held tightly0006
  • Creates a beautiful surface that, if done correctly, will not look like a 3D printed object

Cons

  • It is usually very expensive to do this at a professional level, and home plating requires a fair amount of professional processing equipment
  • Electroplating at home can cause electric shock if not followed

    Well, that's all we have! We hope this article was useful for you!

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    3D printed plastic post-processing, mechanical and chemical

    The most popular finishing methods for 3D printed objects are sanding, sandblasting and solvent vapor treatment.

    It is a misconception that 3D printing cannot produce objects that are as smooth and polished as traditional industrial technologies. Such claims can be countered with simple sandpaper, and this finishing technique is very common.

    Which finishing technique is used depends largely on the geometry and material of the part. These factors determine both the level of aesthetics that can be achieved and its functionality, because different methods allow you to achieve different textures and appearances. Some methods are better suited for prototypes and exhibition models, while others are better for machine parts.

    Sanding

    Although fusing systems are designed to produce high-quality parts directly from the printer, the layer lines remain visible and the end user does not need this at all, especially when it comes to a solution in which the aesthetic appearance is priority. Sanding eliminates these shortcomings and can be used for models, sales samples or concepts, fully functional prototypes and end-level assemblies and mechanisms.

    Many high-quality 3D-printed objects can be smoothed with sandpaper to get rid of lines where layers overlap.

    Everyone knows the process of sanding. Plastic parts are processed by hand or on a grinding machine, as is done with wooden or metal elements. Sanding is inexpensive and effective, and it is a proven method by which a quality finish can be achieved. In fact, this is the most common way to refine 3D printed objects.

    All but the smallest details can be sanded with sandpaper. And they can be large as much as you like, although it can be difficult to manually get to small defects and irregularities. In typical situations, the process is relatively fast. In layer-by-layer welding, we are usually talking about the fight against stepped surfaces. Steps on a part the size of a remote control take about 15 minutes to clean, while painting the same part takes 2 hours due to additional steps such as preparation and drying.

    When a part must be precise and durable in the first place, it is very important to consider how much material will be removed by sanding. If a lot of it is removed, it is necessary to make changes to the design before printing, to make the walls thicker. The requirements for the part also determine which sanding technique will be used, manual or mechanical, and which tool will be used.

    Sandblasting

    The second most common finishing method is sandblasting. In this case, the operator controls the nozzle, from which a finely dispersed material is sprayed under pressure onto the part in order to hide traces of layers on it. The process is fast, takes 5-10 minutes, the result looks whole.

    When sandblasting a part placed in a closed chamber, a stream of small plastic particles is sent, resulting in a smooth surface after 5-10 minutes.

    This technology is easily modified and can be used with most materials. It is also used during the development and manufacture of a part, at any stage - from prototyping to production. This kind of flexibility is due to the fact that processing is usually done with fine particles of finely processed thermoplastic. It is this "sand", the abrasive characteristics of which, when sprayed, are in the range from medium to high. Baking soda works very well as it is not too harsh. However, it is somewhat more difficult to work with than with plastic.

    One of the limitations of sandblasting is the size of the object. Since the process is carried out in a closed chamber of limited volume, it is usually up to about 60 x 80 x 80 cm.

    Steaming

    The third most popular finishing method is called steaming or steaming. In this case, the part is in an atmosphere of evaporation of a substance brought to the boiling point. The particles of the evaporating substance are fused into the treated surface to a depth of approximately 2 microns, making it smooth and shiny in just a few seconds. Those who prefer a matte finish can sandblast the part after steam blasting, when the part has already been smoothed and mechanical contact stress has been removed.

    Acetone vapor treatment of ABS plastic makes the surface smooth and glossy, the only drawback of this technology is that corners and small parts are folded

    Since the surface is very smooth, vapor treatment is widely used for consumer goods, prototypes and medical applications. The method does not significantly affect the accuracy of the part.

    Learn more