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

 

This “how to” will teach you the best practices associated with sanding your 3D prints.

 

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

 

Supplies Required:

- Sandpaper (80, 120, 240, 200, 1000, 1500 grit)
- Handheld electric sander
- X-acto Knife
- Needlenose pliers
- Flush cutters
- Chisels
- Bin to hold water
- Respiratory mask
- Eye protection
- Gloves

 

 

 

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.

 

 

 

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

 

Step 2: Roughing

 

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

 

Tip:
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

 

Tip:
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.

 

Step 3: Sand with Coarse Grit Sandpaper (Dry)

 

Supplies used: Electric sander and 80 grit sandpaper

 

A. Begin sanding with coarse (80 grit) sandpaper

 

Tip:
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 colour. The shine will return as you move to higher sanding grits.

 

Tip:
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 multi-tool. 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

 

Tip:
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.

 

Step 5: Sand with Fine Grit Sandpaper (Wet)

 

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

 

Tip:
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

 

Final Part

 

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.