Polish a 3D Printed Part Using Jewelry Polishing Techniques

You might have read the instructable on how to polish big resin pieces from the Objet 3D Printers. But what if you want to polish a small but complex part? When a sander is too big and powerful for your delicate little part? In this instructable I'll demonstrate how you can polish a small 3d printed part using jewelry polishing techniques.

This method works for: investment-casted metal pieces, 3d-printed metal pieces (steel, bronze, precious metal, etc.), and 3d-printed resin pieces.

Step 1: Set-up Work Station

Since our part is small, we need good control on our hands to polish it well. A flex shaft is ideal, but if you don't have one, you can easily modify a dremel into a flex shaft using a simple attachment. When you purchase this attachment make sure to check if it works with your dremel model.

Attach the flex shaft attachment to a dremel, and find a spot to hang your dremel upright. (You don't want to put it on the table since the vibrations will be super annoying). Make sure the cord of the attachment forms a light and easy curve from the head of the dremel to your working table. A sharp curve will damage the tool.

Step 2: Polishing Wheels

Jewelry polishing wheels (here I used AdvantEdge silicone polisher) come in different grits, sizes and shapes. These different shapes (disk, flat-edged disk, teardrop) are very efficient in working on complex geometries.

The white wheels are the most coarse, relatively equal to 400 grit sand paper; the black wheels are medium coarse, relatively equal to 800 grit sand paper; the blue wheels are fine wheels, and can bring your part to at least 1200. There're finer wheels than blue too, in pink, but usually for general purpose blue is fine enough.

Use a screw mandrel to secure a wheel to your dremel. If the mandrel is too thin for your dremel opening, an easy hack is to tape it to make it thicker.

You can purchase all of the polishing wheels as well as the screw mandrel from Rio Grande.

Step 3: White (coarse) Wheels

Clean and dry your 3d printed part thoroughly. Here I printed a model of a chicken pox virus using vero clear on an Objet 3D Printer. You can see all the texture from the 3d printing process very clearly.

Start with white wheels. They are very efficient in removing the 3d printed texture and other small scratches. Recommended speed is 1,000–5,000rpm with very light pressure. If you press too hard, you start to create new dents on the surface.

After using white wheels, the whole surface will look blurry. Clean your part and examine if there're still scratches left. The white wheels should be able to get rid of all major scratches on the surface.

Polishing wheel dust is annoying so make sure you wear proper protection gears (respirator / mask, safety glasses, apron, etc.) while you're polishing.

Step 4: Black (medium) & Blue (fine) Wheels

Continue with black wheels and blue wheels. Your part should become more and more clear when you move up grit.

Step 5: Sand Paper

An alternative sanding technique is to use sand paper. Similar to polishing wheels, jewelry polishing sand paper comes in many different grits. The green sand paper (400 grit) and grey sand paper (600 grit, no picture here sorry) are frequently used to remove small scratches. All these sand paper is for dry sanding. Note that although the green sand paper might seem pretty coarse (400 grit for example), they are actually very fine and soft sand paper and are not really comparable to the white polishing wheels. They're better for later stage polishing when you already have a pretty smooth surface.

Sanding with sand paper by hand is very labor intense. But here's a little trick. Stick a small piece of sand paper in a slotted mandrel and now you can use your flex shaft / dremel to drive the sand paper.

Some jewelry polishing sand paper can be super fine (6000 grit) which is a little bit unnecessary for general purpose. But go for it if you're OCD.

Step 6: Polishing Compound

The last step in polishing is to use some polishing compound. Use a brush wheel with tripoli (a pre-polishing compound) first. Then wash your past thoroughly before you move on to rouge. This is to prevent the rouge wheel from contaminating with left-over tripoli. If you have a ultra sonic cleaner, soak your part in warm soap water for 5 minutes to get rid of all the tripoli.

Then use a cotton or felt fluffy buffering wheel with rouge. Your part should start to have a beautiful shine at this point. If the rouge is somehow stuck on the surface, it means either you're not pressing the wheel hard enough, or your surface is not smooth enough for the final step and you should go back to previous steps.

Step 7: Final Result

The finished result should be smooth and shiny.

One last note: there's no fixed method of polishing. Wet sanding should also work for this test piece. Just try out different combinations and see what works best for you. Happy sanding!!

Comments

[DavidP124]

Hi!

I love this instructable. How do I keep a piece of sandpaper in my mandrel so I can polish a piece from rough to smooth? I have a set that look just like yours. Adding a strip, turning it on (low BMP), causes nothing but chaos, nothing equating a useable tool. How do you get it to work?

[ndanner]

I don't understand how to use those dremel wheels on the item. At what angle ware you pointing the disks at the item? Could you add a photo? I bought a dremel with those attachments but for other reasons, I never used them. I thought most of those brown disks that you show in the first image were to cut away bolts and nails? Strange.

[wei wei]

Please see step 2 to get more info on the polishing wheels. These are NOT the ones that often appear in dremel bit set, and you're right, those are used to cut parts off. The ones I used here are made of silicone, they're very soft and are made to polish jewelry. You can get them from Rio Grande. Use the wheels perpendicular to the surface. You'll know immediately once you get the right wheels.

[ndanner]

Do you think that this will also work on PLA printed 3D prints or only resin?

[wei wei]

Oh I'm not sure......I used this method only on resin. I think it might not work on PLA, since using dremel with polishing wheels will add quite a bit pressure on the surface, and if the piece is not strong enough, it might shatter the piece.

[ndanner]

Thanks for the fast reply, will look into this for my PLA!

[Suraj Grewal]

Wow man ,the thing you printed doesn't look like its from this world,it looks like some microscopic alien microbe,

How did you obtain those reflective surfaces (what material is that?)

[jarikcbol]

Yeah, the unpolished version (with the printer lines) looks like an image from an electron microscope.

[Suraj Grewal]

btw,it looked better before polishing,had it been a showpiece representing some virus

[wei wei]

Sorry to hear that....I would agree that it looked more like a virus before polishing :)

It's part of a bigger project I'm working on right now. Stay tuned for more viruses!

[wei wei]

That's clear resin (vero clear) printed from an Objet 3d printer. This method will work for casted resin polishing as well.

[oldmicah]

Fantastic description! Thank you.

Two questions: In step six you use a wire brush on the piece? I would have guessed that it would scratch the heck out of the piece at that point.

Second question: About how long did it take you to polish the virus?

Thanks again!

[wei wei]

Thank you for the question!

1. In step six it's not a wire brush but a wheel with soft brush. I looks rougher than it actually is.

2. I took about 2 hours for the whole process.

[Raitis]

It looks more like a plastic brush, search for Dremel 403.