Another Ambassador Moment: Sanding and Finishing 3d Printed Parts!

2022-11-02 | By Will Siffer

License: Attribution Non-commercial 3D Printer 3D Printing

With this project, I am continuing my long-term scale model Boilermaker Special project. Since the scale of this project is so large, the parts don't all fit on the print bead of my printer. This was my first time sanding and painting a 3d printed part and I definitely learned a lot for next time, so follow along and use this as a way to get started and learn from my mistakes!

What do you need to get started?

• 3d printed parts!
• Sandpaper - I used 60, 80, 120, 180, and 220 grit sandpapers.
• Epoxy - 2-part epoxy tends to work the best for me to bond 3d prints.
• Body Filler
• Sandable spray on primer
• Paint

Getting started

The first step of finishing 3d printed parts is to sand all the individual components until they are smooth enough to not feel any layer lines or imperfections on the part. For me I worked through all the sandpaper grits I listed above and worked back through them to get each individual part perfect before gluing them together.  

Once I had each part completely sanded down, I used 2-part epoxy to bond the parts together. This is an extremely strong bond that so far hasn't failed me yet on my prints, and it dries in 5 minutes, so you don't need to clamp them for very long.

Finishing 

This is where I made a mistake. I only used body filler on the large gaps rather than the full part. After I painted you can still see some of the layer lines which wasn't the goal this time. I decided to keep the lines for now and maybe go back and fix them later, but in case you want that flat - gloss finish, definitely use body filler on the whole part.

Once coated with body filler, sand with 80 grit sandpaper to smooth and shape the filler.

Finally, it's time to spray on the primer. I used 3 coats with 2 light coats and 1 last heavy coat of spray-on primer so I could sand it smooth just before painting. I thought that the primer would do more here, which is why I now recommend that you use body filler on the whole part. 

When you finish sanding and priming, it's time to paint! This is the easiest part since the preparation you did up to this point will do the work for you. Just make sure to paint at least 3 light coats on top of each other to prevent dripping and to get that nice, finished work. 

Once you are done painting you are ready to add the part to the rest of the assembly! Go ahead and pat yourself on the back and admire the beautiful piece of art you just made!