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This, highly customizable, universal cuff, capacitive stylus reuses the stylus tip and stylus extender concepts from the 6th finger/toe capacitive stylus but replaces the finger/toe rings with a palm loop for those individuals who lack fingers or lack the ability to rotate their wrists sufficiently to position the stylus above their tablet or smartphone.
Unlike the 6th finger/toe stylus there’s no option for using a bolt and nut to conduct the electricity to the individuals skin, so all versions of the Universal Cuff Capacitive Stylus use conductive filament (like the conductive PLA available from ProtoPasta) to carry the electrical signal between the user’s skin and their tablet or smartphone.
Here’s a quick video that demonstrates how you can use other conductive materials like conductive foam and conductive tap in concert with a stylus made of conductive filament:
First Things, First:
The program for creating your own custom universal cuff stylus is located here on Thingiverse.
The first step will be to decide how you want to do your customization. You can use the Thingiverse Customizer but it’s really slow and clunky [Instructions for using the Thingiverse customizer can be found here.]
We recommend that you use free software called OpenSCAD, instead. [Instructions for downloading and installing OpenSCAD on your computer can be found here.] The images of the user interface shown on this page come from OpenSCAD though the user interface of the Thingiverse Customizer will be very similar.
If you decide to use the Thingiverse Customizer, just click the “Open in Customizer” button to the right of image on this page. If you’ve downloaded and installed OpenSCAD, click on the “Thing Files” tab which will take you to this page, and click on the file called “universal_cuff_stylus.scad” to download the program and open it with OpenSCAD.
Second Things Second:
You need to decide on the basic shape of the palm loop and whether or how it will support the user’s thumb.
The starting palm loop shape looks something like this:
This design is made to be used with a fixed (4 or 6-sided) turret. There are two mounting points for the turret on top of the palm loop. The one on the left is aligned with the user’s index finger and the one on the right works well for a stylus that is oriented at a right-angle to the user’s arm.
The latest version of the palm loop is designed to work with a rotating turret. More on that topic below.
The palm loop goes onto the individual’s palm with the largest opening on the user’s thumb side and the smaller opening on the user’s little-finger side.
For individuals without fingers or a thumb this style of palm loop may be optimal. It can be made wider to provide greater stability on the palm.
In this image, the palm loop is comprised of multiple different filaments. The conductive filament is black (for now), so to make the stylus more attractive to the user and to limit the amount of the conductive filament needed, it can be sandwiched between two other colors that are favorites of the user. In this example, the user is a Denver Broncos fan, hence the choice of orange and blue filaments.
You can also add two features to accommodate the user’s thumb and provide additional stability. The first is a simple “thumb rest”:
If it would be uncomfortable for the user to place their thumb on the rest, it’s possible to add a “thumb loop mount” to the palm loop and insert a thumb loop at any one of six locations along the mount:
The thumb loop printed separately and sized to fit the user’s thumb. Note that the thumb loop doesn’t need to be made of conductive filament. There’s already sufficient conductive filament in the palm loop to provide the electrical connectivity with the user’s skin. In fact, all it takes is a small amount of the user’s skin to be in contact with the inside of the palm loop. The rest of the inside can be lined with padding if that makes wearing the loop more comfortable for the user.
Finally, you can add a circular grip to the bottom of the palm loop for users who can apply pressure with their fingers. The grip can be used with thumb support mounts or without:
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Third Things Third:
You’ll now need to gather measurements of your palm and determine the length of the stylus. If you plan to use a thumb loop as well, you’ll need to measure the diameter of your thumb.
The palm loop measurement tool will give you the length, height, and width measurements you’ll need.
Use the measuring rings to easily determine the diameter of your thumb.
Fourth Things Fourth:
Let’s look at how you use the program’s user interface to design and customize your universal cuff stylus.
The customization options are organized into several categories:
The Part to Print category is where you indicate which part of the stylus you’d like to print.
The Palm Loop Info category is where you specify the size of the palm loop and how/if the palm loop will support the user’s thumb.
The Stylus Info category is where you specify the length and width of the stylus and whether the capacitive tip will be mounted to the stylus with a 4 mm nut.
The Thumb Loop Info category is where you provide sizing information about the thumb loop.
The Circular Grip Info category is where you provide sizing information about the thumb loop.
As you specify each stylus part that you need, start at the top of the set of categories and work downward. Begin with choosing the type of part that you want to print. It will be helpful to see the part displayed in the user interface as you provide more specific details later.
Part to Print Category
The Part to Print category has a single item – a pull down list of possible parts:
You will need to print a palm loop, stylus tip, and a turret for any stylus. You can also print a stylus extender, thumb loop and/or circular grip.
Choose palm loop to begin the process. A default stylus tip will be displayed. If you are using OpenSCAD to customize the stylus you will see a slightly fuzzy image:
The rendering process will clean up the display, but if you wait to the end to render your design, then design changes you make will be displayed very quickly. If you’re using the Thingiverse Customizer you won’t see the fuzziness because the image is automatically rendered but will take extra time to display after each change.
After you make all changes and render the palm loop, you’ll see a cleaner image:
The default palm loop is designed to be used with a rotating turret for attaching the stylus tip to the palm loop:
You can also mount the stylus tip to the palm loop with a fixed turret (either 4-sided or 6-sided):
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The advantage of the rotating turret is that it’s easy to change the angle of the stylus tip relative to the palm loop. The disadvantage is that it requires a couple of other parts – a 4 mm nut and an M4x20 mm bolt.
The advantage of using a fixed turret is that the mount is very stable and doesn’t require any additional hardware. The disadvantage is that it can be difficult to reposition the stylus tip if you need to change the angle between the tip and the palm loop.
If you go with a fixed turret then the palm loop will have two slots in the top where you can insert the turret:
As you specify your stylus more, the size and shape of the palm loop may change.
Palm Loop Info Category
Here you set three key dimensions for the palm loop. These are the same measurements that you took using the palm loop measuring tool. Here’s how they affect the size of the palm loop:
Next, you can decide whether to provide additional support for the user’s thumb by including a thumb rest or a thumb loop mount as part of the palm loop. Note that you can’t include both a thumb rest and a thumb loop mount at the same time.
Finally, you indicate the type of turret you want to use in your design. The default is “rotating” but you can choose to go with a “fixed” turret, instead. If you go with a rotating turret, you will need to download the STL file for the rotating turret from Thingiverse. You also need to get a 4 mm nut and an M4x20mm bolt.
Stylus Info Category
Return to the Part to Print category and choose “stylus tip” from the “part” pull-down list. You’ll see a stylus tip displayed based on the starting option values:
The Stylus Info category has three options. The first is called stylus width. The starting value is 10 mm but you can make the stylus thinner or thicker. A thinner stylus will be lighter but slightly more fragile. Also a conductive filament stylus that is thinner than 10 mm won’t support an opening for a 4 mm mounting nut. At the same time, a thick stylus may be cumbersome for a small user.
The starting value for the length of the stylus tip (or an, optional, stylus extender) is 20 mm. You can only have one stylus tip but you can have an unlimited number of stylus extenders. Each of them can be up to 200 mm long. The longer the stylus, the more unwieldy it becomes. Still, if you need a very long stylus, then you have no choice.
If you want to add a 4 mm nut to mount the capacitive tip more sturdily select yes from the “use 4 mm nut to mount tip” pull-down list.
Setting the length to 50 and using a nut changes the image to look like this:
A slot has been created for the nut and the stylus tip is longer.
Thumb Loop Info Category
The Thumb Loop Info category has two options for specifying the size of your thumb loop. In order to properly mount your thumb loop, you must have added a thumb loop mount to your palm loop in the Palm Loop Info category.
To see the thumb loop displayed, return to the “Part to Print” category and choose “thumb loop” from the “part” pull down list. You’ll see a starting image of a thumb loop:
You’ll use the measurement you took with the measuring rings to set a value for thumb diameter. The value for thumb width will depend on the amount of support required by the user.
Circular Grip Info Category
The Circular Grip Info category of options has a single value and that is the preferred diameter of the circular grip. The diameter you choose will depend on how much the user can bend their fingers and how much padding you’d like to add to the grip.
To see the grip displayed, return to the “Part to Print” category and choose “circular grip” from the “part” pull down list. You’ll see a starting image of a circular grip:
The grip has a groove cut along it’s length for gluing it to the palm loop. The groove is slightly wider than the palm loop width to make attachment easy. The length of the grip is determined by the length of the palm loop. If you’d like to make the grip shorter or longer, adjust the length of the palm loop (without printing a new palm loop).
Choosing a Turret
You’ll see three turrets in the list of parts to print – a 4-sided fixed turret and a 6-sided fixed turret – you will also see an option for a rotating turret but if you choose that option you will just see text telling you how to download the STL file for the rotating turret from Thingiverse. The two fixed turrets look like this:
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The turret you choose will, mostly, depend on the number of options you want to have for the angle between the stylus tip/extender and the user’s arm. [Note, if the width of the stylus falls below 9 mm, the program will only allow for a 4-sided turret because a 6 sided turret would be too fragile.]
The following picture shows the 4 directions that the stylus tip/extender can be mounted on a 4-sided turret (note the angles with respect to the palm loop):
The next picture shows the 6 directions that the stylus tip/extender can be mounted on a 6-sided turret (note the angles with respect to the palm loop):
Of course, the actual stylus will only be in one of these locations at a time.
The turret is pictured in black because it must be completely printed in conductive filament in order to ensure that the conductive filament layer of the stylus tip/extender makes contact with the conductive filament layer of the palm loop.
The turret you choose will depend on the angle that the user needs to use to interact with their tablet or phone.
See the video below about assembling and using the rotating turret.
Fifth Things Fifth (assembling your stylus):
The following video shows you how to assemble your customizable universal cuff stylus:
That’s it! Put the stylus on your hand and try it out!
More Flexibility
You may find that you need more flexibility in angling the stylus – more than you can achieve simply by rotating it around the palm loop. In that case, you can print and insert further rotators. They come in two forms that rotate in different planes. The first, named “rotator up-down”, rotates the tip of the stylus up and down. The second, named “rotator side-to-side”, rotates the tip from side to side.
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| Rotator up-down | Rotator side-to-side |
You can insert both rotators into the stylus and point the tip a in just about any direction.
The each rotator comes in two parts. The two parts are joined together with an M3 nut and a 10 or 12 mm M3 bolt. Both parts of the side-to-side rotator should be printed with supports. Download the STL files for the rotators directly from Thingiverse.
Note that the rotators should be printed entirely out of conductive filament.