Ruler That Does Not Move on the Paper When Pressed—DL-24

For (With Whom)

People with left hemiplegia after a cerebral hemorrhage, with motor and sensory impairment, who cannot hold the ruler in place because the tension in the fingers of the left hand rises when they position the ruler, press it with the left hand, and try to draw a line with a pen in the right hand. * When drawing lines, both hands

Why

The user requested help, saying, "I tried to draw a simple drawing, but I couldn't use the ruler well." We thought the user could not hold the ruler in place because of sensory impairment, increased muscle tone accompanying movement of the unaffected side, and divided attention, and sought a solution through a compensatory approach.

How

We had the user use an ordinary ruler and observed the task of drawing lines on paper. The user could align the ruler and press it with the fingers of the left hand, but when trying to draw a line with a pen in the right hand, the tension in the left fingers rose and the ruler moved. We thought it might be solved by creating a mechanism that can switch the fixing of the paper and ruler ON and OFF. A drafting machine for technical drawing has that function, but here the user wanted a ruler that could be used casually. We also considered non-slip materials such as magnets and rubber, but taking into account that it must be possible to position it freely, that the grip must be switchable ON/OFF at will, and the production process and cost, we aimed to make it with 3D-printed parts only as far as possible. We came up with a mechanism that uses the resilience of the resin like a spring, so that the fixing part presses against the paper to hold it and lifts away to move, then designed and printed it. After the user actually tried it and we repeated improvements, it was completed after 10 prototype models were made and tested (image at upper right). Respecting the user's opinion that "it has to be accurate," we deliberately did not add graduation marks.

Outcome

Drawing lines on paper for making drawings can now be done repeatedly without stress and without the lines being misaligned.

Materials Used

Body: PLA

Approximate 3D Print Weight

17g

Print Settings Overview

Body: Nozzle diameter = 0.4mm, Layer height = 0.1mm, Infill = 20% (no basis for the setting because it is thin), Temp = 210°C (to suit the filament), Speed = 20mm/s (slow), Support = None

Accessory Information

None