Lasercut Keyguard Instructions V0.1
User Manual:
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Laser Cut Keyguard Instructions
This guide describes a workflow to assist a maker to design a custom lasercut keyguard for an
Augmentative and Alternate Communication (AAC) device.
An AAC device is used to help someone communicate. AAC devices may be comprised of a
variety of different tablets, (tablet cases) and apps. The AAC apps may also provide options to
customize the number, size and layout.
A keyguard is a thin plate that sits over top of an AAC device. The keyguard can help a user use
the AAC device more easily and more effectively. The openings in the keyguard can help
provide focus, tactile feedback, and the ability to rest the user’s hand on the device without
activating a button, reducing fatigue.
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Overview
The overall process involves measuring the users device, designing the layout of the Keyguard,
preparing the vector file for Laser cutting, Laser cutting the Keyguard, and mounting the
Keyguard.
Equipment
Creating a custom lasercut keyguard requires the following items:
Computer with vector graphics software.
o Inkscape
o (Optional) Autodesk Fusion 360
Measuring Tools
o Ruler
o Measuring Tape
Keyguard Material
o Cardstock or cardboard to test fit
o 1/8 in. or 1/16 in. acrylic
Mounting
o Suction tape
These instructions will refer to steps in Inkscape, but alternative vector graphic software such as
Adobe Illustrator or Corel Draw may also be used.
1. Gathering Device Information
The first step is to gather information about how the user uses their device and then get the
physical size of the device and app to create an appropriate keyguard.
Usage
Does the user want access to the on-screen buttons for editing, menu, iPad home button, etc.,
or is the keyguard to block access?
What size and shape of openings are required?
Should any additional information be marked on the keyguard?
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Device Measurements
If the user’s device and AAC application is available, measurements can be made directly.
In some cases, the user may submit a photo of the device with some measurements that can be
used to scale and determine the measurements.
Capturing A Reference Image
To accurately measure the position of the various buttons, it can be helpful to capture a
reference image. To ensure the final keyguard properly fits the device and the openings match
the buttons, it is critical that the reference image can be scaled properly.
To capture a reference image, accurately measure the cut a piece of paper to a length that
spans the longest edge of the device. Accurately measure the length of the piece of paper and
write it on the paper. It is important to know the distance of the screen opening to the closest
milimeter or 1/16 inch.
Take an image of the device with the app running and the piece of paper. Try to position the
camera so the device is not skewed.
If possible, capture a screenshot of the image as well. See the appendix for instruction on how
to capture a screenshot of the app.
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Using The Reference Image
In order to use a device photo to design the keyguard layout, the image needs to be rotated and
scaled.
Import Reference Image
1. Open Inkscape.
2. Select File > Import
3. Select the reference image. Press Open.
4. Press OK to use the default import options.
Rotation
Rotate the photo so that the tops and sides are aligned with the horizontal and vertical axes.
Tip: Use the measuring tool (ruler icon on toolbar, or ‘M’ on the keyboard) to measure the angle
of part of the image that should be horizontal.
Scaling
Scale the image so that the size of the image on the computer matches the size of the device.
Use the measuring tool to measure the known distance in the reference photo. Change the units
to match the known measurement.
Calculate the required scaling factor by dividing the distance measured from the photo by the
true distance measured on the device, then multiplying by 100.
For example, if the distance measured from the photo is 25 inches and the true distance is 5
inches, the scaling factor is:
5/25 * 100 = 20%
1. Click Object > Transform
2. Click on the Scale tab.
3. Make sure the ‘Scale Proportionally’ is checked.
4. Enter the scale factor calculated above.
5. Click Apply to scale the image.
2. Keyguard Layout
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Design Considerations
Message Window Size Settings
Many AAC applications have a message window near the top of the screen. This message
window may be adjustable to allow the user to set the number of lines and the text size.
Changing the message window size affects the size of the buttons below. Increasing the
number of lines or text size of the message window will cause the cause the buttons below
to reduce in height.
Camera Access
Don’t cover the camera.
Symmetry
In some cases, it can be helpful to make the keyguard symmetric about a vertical axis so
that the device can be rotated.
Material Thickness
Thicker keyguards may help reduce the number of accidental touches.
Robustness
Round the corners of the keyguard to remove the sharp edges.
Try to avoid skinny section, especially near the edges, that may cause the keyguard to
crack or break.
Mounting
How will the keyguard be mounted to the device?
Keyguard Design
Using the reference image as a reference, add rectangles and circles to match the outline and
the openings for the keyguard.
TIP: Use rectangles and circles and set the dimensions using the top bar.
Marking
Adding some laser etched marking can make the keyguard easier to use for the user, caregiver,
or therapist, by helping identity for which app, device and/or user the keyguard belongs.
One way to add text that is fast to etch as lines with the laser cutter is to use the Hershey Text
plugin in Inkscape:
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1. Extensions > Render > Hershey Text
2. In the Hershey Text dialog box:
a. Type in desired text
b. Select Action: Typeset that text
c. Select Font Face: Sans-1 stroke
3. Click Apply.
4. Adjust the size and position of the text as desired.
This will create a single-stroke vector path that can be quickly etched using the laser cutter.
Use these steps to add “makersmakingchange.com” near an edge of the keyguard. In order to
be legible, the text should be ⅛ inch (3 - 4 mm) in height. This will allow the user to locate the
plans for a replacement or request a modification to their keyguard and provide an opportunity
for other potential keyguard users to request their own keyguard.
Customization / Personalization
Add any additional information requested by the user to the keyguard. This may include, for
example:
Name
Organization
Phone number
App / App setting
Etc
Try to position the text in a location so that it will not obscure the screen. The space on either
side of the camera or Home button is usually a good choice.
Laser Cutter File Preparation
Once the geometry of the keyguard has been finalized, the next step is to prepare the design for
laser cutting. These instructions may vary depending on the laser cutter and laser cutter
software.
Operation
Stroke
Fill
Width
Cut Line
Red (R:255,G:0,B:0)
None
0.01mm
Engrave Line
Blue (R:0,G:0,B:255)
None
0.01mm
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Engrave Area
None
Black (R:0,G:0,B:0)
0
Cut lines are meant to cut through the entire depth of the material. The outside outline and all of
the button openings should be set as Cut Lines.
Engrave lines will engrave a line a limited depth. Single-line text markings should be set as
Engrave Lines.
Engrave Area will engrave a closed area. This can be useful for adding closed shapes, but
takes longer to do on the laser cutter.
Save the design file using the following naming convention:
{FirstName}{LastInitial}{Number}_{Revision}.svg
Save a copy as a PDF for laser cutting using the same naming convention:
{FirstName}{LastInitial}{Number}_{Revision}.pdf
For example, the initial design for John Smith’s first keyguard should be saved as:
JohnS01_1.svg
AND
JohnS01_1.pdf
Data Transfer
Transfer both the SVG and PDF file to a USB flash drive.
3. Test-cut
This is a recommended but optional step.
Before cutting the keyguard out of plastic, it is helpful to test the fit to see how well the
design matches up on the device and how well the openings match up to the buttons on the
application. To quickly and inexpensively test the fit, we can laser cut the keyguard out of
cardstock or cardboard.
Laser Test Cut
Bring the USB stick with the PDF design file to the laser cutter.
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Assessing Fit
The keyguard should sit flat on the touchscreen. A little wiggle room is better than too tight.
The openings should match up with the buttons
Refinements
If necessary, adjust the size and spacing so the keyguard fits the device and matches the
buttons properly.
4. Final Cut
Final Design Checks
□ If possible, have you cut a design to test the fit?
□ Are the corners rounded?
□ Is the keyguard marked with makersmakingchange.com ?
□ Is the keyguard marked with any requests from the user (name, app, etc)?
Laser Cutting
Bring the USB flash drive with the final design files to the laser cutter so the keyguard can be
cut out of acrylic.
5. Finishing
There are a few final steps to make the keyguard ready for use.
Smoothing
Check to make sure there are no sharp edges on the keyguard outline or any of the openings. A
sharp knife or small file can be used to smooth over any sharp edges.
Mounting
There are a few different methods for mounting a keyguard on to an AAC device including:
● suctions cups
● velcro
● suction tape
● magnets
● under the case
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Suction tape (or "suction cup tape") bonds to smooth, flat, clean surfaces just like a suction cup.
Though not actually suction cups, the surface of this tape has thousands of microscopic craters
that work by creating many partial vacuums between the tape and the target surface.
The tape is not pressure sensitive, can re-bond repeatedly, and leaves no residue on the target
surface. To remove, you simply pull the tape off or twist it to break the bond.
1. Cut some narrow strips of suction tape.
2. Attach the strips of suction tape to the edges of the keyguard.
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Appendix
iPad Screenshot Scaling
To capture a screenshot on an iPad device, load the app and hold the device in the desired
orientation. While holding down the On/Off button, press the Home button. The screen will flash
to indicate a screenshot has been captured.
The screenshot image will be 1024 pixels wide and 768 pixels high regardless of the actual size
of the screen on the device. In order to scale it properly, use the conversion factor in the table
below.
iPad Type
Screen Width
(mm)
Screen Height
(mm)
Conversion
(px to mm)
iPad
198.1
149
0.193
iPad2
198.1
149
0.193
iPad 3rd generation
198.1
149
0.193
iPad 4th generation
198.1
149
0.193
iPad 5th generation
196.47
147.39
0.192
iPad Pro 9.7-inch
203.11
153.71
0.198
iPad Pro 10.5-inch
213.5
160.13
0.208
iPad Pro 12.9-inch 1st Generation
262.27
196.61
0.256
iPad Pro 12.9-inch 2nd Generation
262.27
196.61
0.256
iPad mini
161.2
121.3
0.157
iPad mini 2
161.2
121.3
0.157
iPad mini 3
161.2
121.3
0.157
iPad mini 4
161.24
121.31
0.157
iPad Air
198.1
149
0.193
iPad Air 2
203.11
153.71
0.198
Source: http://volksswitch.org/index.php/volks-devices/fully-customizable-3d-printable-aac-
keyguard-for-tablets/using-app-screenshots-to-determine-the-app-layout/
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Fusion 360 Workflow
Autodesk Fusion 360 is a cloud-based, computer-assisted design program with a free license
for hobbyists and enthusiasts. Fusion 360 requires a 64 bit system and either Windows or MAC
OS. To access the hobbyist license, you’ll need to sign up for an account and download the free
trial: https://www.autodesk.com/products/fusion-360/overview
Fusion 360 has a few features that make it a useful tool for designing custom laser cut
keyguards.
Insert Canvas
1. Under the insert menu, select Insert Canvas
2. Choose the top plane
3. Select the image
4. Rotate the image to align the edges with the grid. You may need to manually enter a
small value (e.g. 1, 0.1 degrees) into the box.
Scale the Image
1. In the Browser bar, click the triangle beside the Canvasses Folder to show its contents
2. Right click on the canvas image you added in the previous step and select ‘Calibrate
Image’
3. Use the mouse to select a first and a second point on the image with a known distance
between them, and then enter the distance value in to the dialog box. Try to be as
accurate as possible when entering the points so the reference image is scaled properly.
Design Keyguard Layout
1. Create a new sketch on the same plane as the canvas.
2. Create the outline of the keyguard using the rectangle tool.
3. Create the keyguard button openings using rectangles or circles according to the users
preference.
4. When finished, close the sketch.
Tip #1: Use construction lines to help align the openings.
Tip #2: To make the design symmetric, add a construction line in the middle and use the
Sketch>Mirror tool to copy openings to the other side. You can also use Symmetry constraints
to enforce symmetry.
Extrude Keyguard Sketch
1. Click Create > Extrude
2. Select the keyguard profile sketch.
3. Set the extrusion distance to 1/16 inch or 1/8 inch
Export sketch
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1. Right click on the sketch
2. Click ‘Save as DXF’
Import sketch into Inkscape
1. Import the dxf file.
2. In some cases the design may be upside down. You may need to rotate the design 180
degrees.
3. Add any marking or text.
4. Change the line color and stroke according to the laser cut file preparation instructions.
Additional Resources
Suction Tape
http://www.keyguardat.com/suction-tape/
3D Printed Keyguard Workflow
http://volksswitch.org/index.php/volks-devices/fully-customizable-3d-printable-aac-keyguard-for-
tablets/
