Introduction: How to Make Your First 3d Printed Round Open Cuff Bracelet!

About: I like to make and create lot's of things! Follow me on Twitter, Thingiverse and Instagram under my name: christinachun to keep up with what I'm making next!

This is a relatively straight forward instructable on how you can make your first 3d printed round open cuff bracelet and print it on your home 3d printer or through a service such as Ponoko, i.materialise, Kraftwurx or Shapeways. I will be 3d printing on my Afinia H-Series 3d Printer.

You should also have a basic understanding of 3d modeling but I will be walking you through my process. The concepts and techniques are not difficult to understand. You can also use any modeling software such as 3ds Max, Maya, or free alternatives such as Blender, Sketchup, Autodesk 123d, and any other programs of your choosing. I will personally be using 3ds Max.

You'll also want a few measuring tools such as digital calipers and a fabric tape measure. The calipers will help you accurately measure in mm for 3d printing and the fabric tape measure can measure the length of your wrist. You'll need to convert those measurements (inches/cm) to mm. You'll always be measuring when designing for 3d print!

Step 1: The Design

Even if you just want to make something that is super easy in theory, a lot can go wrong. It's important to know the size and dimensions of whatever you're planning to make. If you're going to 3d print at home, then you'll be limited by the size your 3d printer can print at. Helpful tools would be Digital Calipers, Rulers and a fabric tape measure. 

To start, you'll want to measure the width of your wrist. The cuff that I will be showing you how to make is a rounded cuff so the measurements won't have to be form fitting since a round shape is easy to get on the wrist. If you want to make a round open cuff bracelet that is more fitting to the wrist, then also measure the thickness of your wrist as well. Write down the measurements somewhere and keep it for reference later. You'll also want to have sketched out a basic design you would like or found some reference pictures of cuffs you like. Having some sort of blueprint on hand is important to keep you on track, even if you don't follow it entirely and just use it as a loose reference. It doesn't have to look that great either (see my example!).

Depending on where or how you will be 3d printing your round open cuff bracelet, minimum wall thickness will be an issue. Shapeways explains this thoroughly, I encourage you to read it. Also, to print in different materials like metal or ceramic, your model will need to meet the minimum thickness requirement. i.e. Shapeways can print in Stainless Steel as long as your model has a minimum wall thickness of 3mm. Also, the amount of detail in your final 3d printed piece is also limited by the materials minimum detail measurement so be sure to check with the 3d printing service that you choose for the exact specifications so that you can create your model with those things in mind. It will save you a headache later on and you won't get your model rejected from their service for not meeting the minimum printing requirements.

Step 2: 3d Modeling: Set Up Measurements

Before we get started with 3d modeling, make sure that you've set up the measurements in what ever program you are using. Since I am using 3ds Max, I will go to:

Customize> Units Setup and then proceed to change the Metric to Millimeters. If you're using another software, check the user's manual on how to set up the measurements.

Step 3: 3d Modeling: Visual Guide

When modeling for 3d print, I like to draw a visual guide like a cube or a sphere if I want to make something large but within my build platform size. In 3ds Max, when you make primitive objects, they have built in measurements in the parameters that you can adjust when you create the object. To start my guide for my round open cuff bracelet, I go to:

Create>Standard Primitives>Tube

In the Front View, I then draw out a Tube by clicking and dragging. You'll notice you have to click and drag one time for the initial size, then click drag again for the thickness or inner wall, then click drag outward to create the height. Don't worry, it doesn't have to be exact or look perfect.

When you created the Tube object, a panel on the right appeared with a section that says Parameters. In this section, you can modify the dimensions of the Tube. If you lost this section, make sure you have the Tube selected and then click on the Modifier tab (second tab). From there, I edited the Radius 1 to be about 37mm, Radius 2 to be about 32mm and the Height to be about 27mm. This would give the inside diameter of about 64mm where your wrist would be. For a round open cuff bracelet, measurements don't need to be super exact to your wrist since the circular shape is forgiving and the open cuff will allow your wrist to fit inside. Then right-click on the object and select Freeze Selection. Now you won't be able to click on it when you're editing other things.

Now that the guide is set, you will begin drawing your pattern.

This would also be a good time to Save (Ctrl+S). Save frequently, you never know when the program you're working in may crash!

Step 4: 3d Modeling: Creating the Basic Pattern - Shapes & Symmetry

Go to: Create>Standard Primitives>Torus

In the Top View, draw out a Torus by clicking and dragging. You'll notice you have to click and drag one time for the initial size, then click and drag again for the inner thickness. I've set the Radius 1 to 3mm and the Radius 2 to 1.5mm. Right-click the object and select Convert To: Convert to Editable Poly.

In the Modifier Tab, add a Symmetry modifier to the Torus by selecting it in the Modifier List. Next to Symmetry, click the + symbol and select Mirror. Hit the W key to activate the move tool, select the X gizmo with the arrows and move it to over like in my example or follow your design.

This would also be a good time to Save (Ctrl+S). Save frequently, you never know when the program you're working in may crash!

Step 5: 3d Modeling: Creating the Basic Pattern - Edge Loops & Bevel

Under Symmetry, click + next to Editable Poly and select Edge.

Select the middle edge to the right side of the Torus. In the Graphite Modeling Tools rollout, go to Edges and click Remove. Now you've deleted the edge loop!

Select the the top Edge of the deleted edge loop and then in the Selection section, click Loop. Now go to the Edit Geometry section and next to Make Planar is XYZ. Select Y. Now you have straightened the edge loop on the Y axis. Hit the W key to activate the move tool and along the Y axis, move the edge loop down a little. Do the same for the other edge loop below and then move the edge loop up a little (see example).

Next, select the edge loop above and below the straightened edge loops. Go to Graphite Modeling Tools>Edges>Remove to delete those edge loops. Go to the Selection section and select Vertices. Hit the W key to activate the move tool and select the vertices that make up those edge loops as shown in my example. Hit the R key to activate the scale tool and along the Y axis, scale the vertices. Then hit the W key and move the vertices over just slightly to the left.

Go to the Selection section and select Polygon. Hit the W key to activate the move tool and select the faces as shown in my example. Then select Bevel in the edit Polygons section. Change the parameters to Local Normal, height 0.4mm and outline 0.15mm. Select the inner faces of this bevel and hit the W key to select the move tool. Move the faces to the left a bit. Select the outer faces of this bevel and go to Edit Geometry and next to Make Planar select the X. Hit the W key to activate the move tool and move the faces to the right a bit. Right-click on Symmetry and Collapse All.

Now go to Editable Poly and select Edge. Select the outer edges of the Bevel (see example) and then click Loop. Go to Edit Edges>Chamfer and edit the Edge Chamfer Amount to 1mm and Connect Edge Segments to 4.

Reminder: This would also be a good time to Save (Ctrl+S).

Step 6: 3d Modeling: Creating the Basic Pattern - Boolean

Now we are going to make a hole in the center of the design. The reason that we are making these shapes in this way, is so that we can have a repeatable pattern. So, for this hole, we will Boolean one object from the other or in other words, subtracting another object from another object.

Go to Create>Standard Primitives>Cylinder

Change the parameters for a Radius of 0.92mm, height of about 10mm and Sides to 12. It's important to match up the geometry of the Torus as close as possible so that when the Cylinder is cut from it, it won't leave a mess of polygons that could make your model look terrible. Also place the Cylinder as center as possible inside the middle of where the two Torus meet (see example). The other important thing about Boolean is the make sure the object penetrates through on both sides if you want a visible hole on each end. So move the object in place checking in all views.

Next you will need to select the Torus object and go to the Modifier Panel, Create>Compound Objects>Boolean

In the Pick Boolean section, select Pick Operand B and click the Cylinder. The Cylinder should be subtracted from the Torus shapes. Then right-click on Boolean and click Editable Poly.

Next you'll want to check the model. Go to Editable Poly, Vertices and then select the vertical vertices to connect (see example). In the Edit Vertices section, click Connect to connect them. Check the other side as well and repeat.

Next you'll see that you have vertices that do not connect. There will be four on the top and 4 on the bottom that need to connect to the corner vertices (see example).

Now you'll see that there are other edge loops that remain and a few other vertices. For this, you can spin the edges to connect. In the Selection panel, select Edge and then select the edge to spin. In the Graphite Modeling Tools panel, go to Geometry (All) and click Spin. You may have to spin a few times to get it to line up correctly. Then select any of the unconnected vertices and select Remove.

If you've done it correctly, there should be no distortion when applying Turbosmooth. Everything should look uniform. To check the geometry, add TurboSmooth from the Modifer List (see example). If everything is okay, then right-click TurboSmooth and delete.

Reminder: This would also be a good time to Save (Ctrl+S).

Step 7: 3d Modeling: Creating the Basic Pattern - Shapes & Symmetry II

In the Top View, select the object. In the Modifier List, select Symmetry. Under Symmetry, click the + symbol to open it. Select Mirror. Hit the W key to move the Symmetry line to the left (see example). If the joining geometry is a little shorter than you would like (or longer) you can edit the vertices under Editable Poly.

Select the Vertices then go to Edit Geometry>Make Planar>X and hit the W key to activate the move tool. Move the vertices over a bit. Under Symmetry, select Mirror and move to join the other side. If you notice that the shape isn't level, with the vertices still selected, you can hit the R key and scale along the Y axis to align.

Add another Symmetry modifier on top of the current one. Hit the + next to Symmetry and select Mirror. Hit the W key and activate the move tool to move the mirrored object to the left like in my example. Only 3 groups of 2 Torus should be shown. Try to get as exact as possible.

Right-click Symmetry and Collapse All.

Now you will need to select Polygon and then hit the W key to activate the move tool. Select the outward faces on the left and right side, leaving the middle group of polygons. Press delete to delete them.

Add Symmetry to the model 3 times, this will create 16 loops. Adjust the center of the Mirror as needed. Right-click Symmetry and Collapse All.

Add Symmetry to the model again. This time, you will change the Parameters. Change the Mirror Axis to Y. Select Mirror and hit the W key to activate the move tool. Move the mirrored object down a bit to create the bottom half of the cuff.

Reminder: This would also be a good time to Save (Ctrl+S).

Step 8: 3d Modeling: Creating the Basic Pattern - Adding the Ends

Now it's time to add the end pieces and close the holes.

In the Editable Poly section, select Outline. Select one end where there's a hole. The mirrored side will already be selected. In the Top View, hold Shift and drag the edge outward (see example). You've just extruded polygons! Now hit the E key to activate the rotate tool. Rotate the edge outline inward at about a 70 degree angle (see example). Hit the W key to activate the move tool and move the edge outline until it meets the other side.

In the Editable Poly section, select Edge. Now select on of the edges on the newly extruded area. Go to Graphite Modeling Tools>Edges>insert to insert a new edge loop.

In the Editable Poly section, select Vertices. Select the vertices from the newly created edge loop. Hit the E key to activate the rotate tool. Rotate the vertices outward about 50 degrees. Hit the W key to activate the move tool and move the vertices to create a U like shape. You can also shape the vertices using the scale tool as well. Have some fun with it and don't be afraid to experiment with different shapes or ideas!

Right-click on Symmetry and Collapse All.

Now you want to re-align the pivot. Go to the Hierarchy tab. Select Affect Pivot Only and then under Alignment, click Center to Object. Then go back to the Modify tab. Hit the + next to Editable Poly and select Polygon.

Select half of the bracelet without the completed end. Delete.

I noticed that the end has too crisp of an edge so I want to delete 2 edge loops on the top and bottom. Select the edges and then go to Graphite Modeling Tools>Edges>Remove. I'll even delete the inner ring and the middle edge loop along the end too as well. It'll give a smoother look when we apply TurboSmooth.

In the Top View, I'll also move some of the vertices over so the hole isn't so big. Next from the Modifier List, add Shell. Change the parameters for the Outer Amount to about 0.41mm.

Now add Symmetry and adjust the mirror position to be perfectly centered. Apply TurboSmooth and inspect the model for any issues.

Reminder: This would also be a good time to Save (Ctrl+S).

Step 9: 3d Modeling: Creating the Cuff

Now you will add a Bend modifier from the Modifier List. This will curve the model into a round cuff shape!

Edit the Parameters to: Angle 333 and Bend Axis X

You should now have a nice round cuff with a small opening. You can alter this however you wish. 

If the pivot is off, go to Hierarchy>Adjust Pivot>Affect Pivot Only>Center to Object. Right-click Bend>Collapse All.

Re-size the cuff if necessary, click R to scale and drag to fit your guide. If the object becomes skewed or distorted, Ctrl+Z to undo. Then click on Use Selection Center icon below Rendering (see example). Then try scaling the object again.

Reminder: This would also be a good time to Save (Ctrl+S).

Step 10: 3d Printing: Getting Print Ready

The next thing to do now that the Round Open Cuff Bracelet is designed is to get it ready for 3d printing!

Continuing in 3ds Max, you will want to export the model as an .STL file. With the model selected go to File>Export and save your model as an .STL (StereoLitho) file.

Then you can double check to make sure your model is watertight using a service such as netfabb Cloud Service. Just upload your .STL file and it will check your file for any errors as well as attempt to fix them. You will receive an e-mail with a link to your file as well as a comparison of the original file versus the repaired file. I find this solution quite fast and works fairly well.

Be sure to check your model though to see how the repair looks. Just because it's repaired, it doesn't mean that the model will look the same as you intended every time. i.e. You may have left some unintentional holes somewhere but when the file is repaired, not only are the holes repaired but other geometry is skewed or pulled into where the hole was filled.

Step 11: 3d Printing: 3d Printer

Not all 3d printers are created equal.

These suggestions are for those of you who have an Afinia H-Series 3d printer or an UP! 3d printer. Some of the settings can be applied to other 3d printers.

Before you start to 3d print your model, you should always check to make sure your build platform is level. Calibration is key to a good 3d print. If you're printing in ABS plastic, a leveled platform can reduce warping. If you've experienced warping, then you should enclose the unit in some way to block drafts from interfering with your 3d print. I personally just use scrap art board or card board and stand it up by scoring a line with a sharp blade to fold the ends, then clipping them together to form walls. Gives me easy access to the printer and I haven't experienced any warping since using it. Also, if you have experienced warping, note what side of the build area your model is lifting from. You most likely need to re-calibrate the height and make adjustments to the leveling of the platform. One other thing, don't scrape your model off the platform, glass or perf board while still clamped to the 3d printer. This can cause calibration issues. You wouldn't want to go through a large print to see a part of your model lifting off one of the edges.

These suggestions are just things that have worked for me so if they work for you too then great.

After you load your model into what ever software powers your 3d printer, you can try out the settings I used or use it as a starting point.

These are the settings that I used to print the round open cuff bracelet on my Afinia H-Series 3d Printer and I printed with Glow in the Dark Blue filament.. This is only the second time I've used this filament and it extrudes differently than other ABS I've tried. I don't have a temperature switch (yet) for my printer but I may need one after trying the Glow in the Dark filament from Octave. My favorite filament so far would be natural and black  which I've printed my other bracelets in.



Part Settings
Angle: 30 Deg
Surface: 3 Layers
Fill: Solid Fill

Support Settings
Dense: 2 Layers
Space: 6 Lines
Area: 8mm
Angle: 30 Deg

That's pretty much it. I've included some photos of the model that was printed from this instructable as well as some other images of similar bracelets I've made that have been sanded, primed and painted after being 3d printed. ABS plastic can be primed with non-acetone based primers that you can buy from any hardware store and painted with any water based paints such as acrylics.. Hopefully this instructable has helped you in some way or at least has given you a decent understanding of how to create 3d objects for 3d print.

*I've also uploaded the .STL file on Thingiverse so you can download and print. This version though, has an extra level of TurboSmooth added.
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