Tactile Caliper: Geomtery Instrument for Students with Blindness

Tactile Caliper is a measuring and drawing instrument for students with blindness. I and Anshul developed the simple mechanical device that allows measurements as fine as 1/16th of an inch.

We took the caliper from idea to market in 2 years of hard work. We founded TacWorks and marketed the Caliper as first in our Squirrel Devices series of products.

Since its launch in March 2016, thousands of Calipers have been sold in the US by National Braille Press, our retail partner. We are currently working on a metric version of the caliper for international sales.

We started with the problem of geometry and measurement for students with blindness and came up with several design concepts. After concept refinement, several prototypes were fabricated for each iteration.

Every design iteration was followed by thorough user demostration and feedback. We worked with users in different age groups and geographical locations. User feedback strongly impacted both function and appearance of the Caliper.

Product Development included machine design, materials selection, prototyping, DFM and DFA, manufacturing design and design documentation. We identified contract manufacturers in China for injection molding and assembly.

The caliper came out in the market in March 2016. We have sold several 1000s of calipers in US and are expanding globally.

Pranay Jain, Anshul Singhal

August 2013 - March 2016

Assistive Technology, Mechanical Engineering, Prototyping, User Experience


P Jain and A Singhal. Tactile Measuring Instrument. US 2015/0243189 A1.


Making it at MIT. MIT Spectrum

Making the Sciences More Accessible to the Blind. MIT Division of Student Life


Squirrel Tactile Caliper. Perkins Accessible Science Blog

Tactile Caliper Provides Braille Output for Blind Users. WonderBaby.org