Our team was challenged with creating a 3D printed device which could assist amputees with tying their shoes. We wanted to design a solution which could work for either left or right-handed amputees and that would not be specific to the type of amputation. With this in mind, we designed a device which attaches to the top of your shoes and holds the laces throughout the tying process. Our design requires two STL files, one for the top clamp and one for the bottom clamp.
Step 1: Printing
The two device files should be for the top and bottom clamps. Opening the files in OnShape, minimal modifications should be required because the device adjusts to various shoe widths. If, however, a wider or narrower size is necessary, the design is easily changed. Opening the sketches for the rectangular top of the device (sketch one), use the dimensions tool to change the length.
For printing, export the two files in STL format with millimeter units. For the top clamp, print the three parts separately and oriented on their backside. By changing the print orientation, the overhangs are reduced which prevents warping and instability. For the bottom clamp, print the part with the default orientation. The file was designed at an orientation to prevent overhangs.
Step 2: Assembly and Attachment
For the bottom clamp, no further assembly of the device is necessary after printing. Thus, simply slide the bottom clamp around the toe of the shoe until the clamp fits tightly. The clamp should be just below the beginning of the shoe laces, and the flat bottom should be underneath the shoe for leverage.
With the top clamp, the three separate parts have to be attached around the shoe to allow for size adjustments. The two L-shaped pieces fit against either side of the top of the shoe, just above the start of the shoe laces. The L-shaped pieces should connect, with the oval with three holes sliding into the second L-shaped piece. With the three holes, the device can be adjusted to match various shoe widths. Once at the desired clamp size, insert the circular pin into one of the holes to lock the clamp in place.
Step 3: Picking Up the Laces
Now that the device has been properly attached to the shoe, grab the shoelaces and loosely cross over each other. Start with the left lace and pull to tighten, securing the lace underneath the second hook. Next, pick up the right lace and tighten and secure underneath the first hook. Once the two laces have been secured, a tight cross should have formed.
Step 4: Weaving the Laces
Unhook the right lace, leaving the left lace secured in place. Weave the right lace underneath the left lace, pulling until the lace is tightened. Secure the right lace underneath the first hook, but leaving slack to form the loops later instead of tightening. Now, the two laces should be tied (as demonstrated above).
Step 5: Forming the Loop
Starting with the slack in the right lace, form a loop by pinching the lace together between two fingers. Hook the loop underneath the third hook, which secures the loop to prevent loosening. Then, grab the top of the loop and tuck underneath the sixth hook, leaving the bottom of the loop secured, to create tension in the lace.
Step 6: Forming the Knot
Remove the right lace from the first hook and wrap around the loop, leaving the loop secured between the two hooks. Next, remove the bottom of the loop from the third hook, leaving the top hooked. Pinch the right lace between two fingers to form a loop, and weave through itself. Secure the right lace underneath the fifth hook, and pull on the loop formed on the right lace to create a tight knot.
Step 7: Removing the Device
Once the knot has been formed, unhook the top of the left loop and the right lace. Remove both clamps from the shoe, and slide into each other for easy storage in a purse or backpack. Now, the shoe should be tied.