A caliper is a tool which measures with more precision than a standard ruler. Calipers can range in price from ~£10 to £40+ for a high end digital model. The homemade caliper can be built in less than 30 minutes and uses everyday waste materials like paper and cardboard, making it virtually free!

Measuring with greater accuracy can allow for tighter tolerances in an object. The use of a caliper can mean the difference between visible gaps or a snug fit in projects!

The idea for this Instructable came from my interest in the maker movement and the possibilities of giving people access to more tools. Perhaps the user cannot afford to spend money on a tool like this, or perhaps amazon prime delivery is just not fast enough and they need one NOW!

At the end of the Instructable some more ideas are given: incorporating a ruler rather than printing one out or 3D printing parts can make a much stronger caliper (but could require money). Printing the ruler gives freedom in terms of the length; I have not seen a caliper measure longer than 20mm, so this could be a chance to build a longer caliper!

Step 1: How to Use a Vernier Caliper

A vernier caliper uses a vernier scale too achieve greater precision. This Wikipedia article on the vernier scale gives all the information possibly needed, but in short, it is a ruler with an added secondary scale which gives extra precision.

- An object is placed between the arms of the caliper, so the arms grip the object.

- The 0mm on the secondary scale will line up on or between two increments on the ruler, indicating the distance in mm

- if the 0mm lies in between two measurements, then the secondary scale will line up with one on the primary. The number which lines up is then the value of the next decimal

- for example, if the 5th increment on the secondary scale lined up with the primary, and the 0mm was situated between 25 and 26mm, then the caliper would be measuring a distance of 25.5mm

(the above GIF was sourced from https://commons.wikimedia.org/wiki/File:Vernier_scale_zero_error_%2B0.10.gif on 23/3/17)

Step 2: Tools and Materials

A list of tools and materials is provided below:

Tools:

- Scissors(or scalpel if you have one and would prefer)

- Printer

- Computer

- Ruler

Materials:

- Paper – doesn’t need to be new, could recycle an old bill, whatever fits in a printer

- Cardboard – again doesn’t need to be new, my supply of cardboard comes entirely from waste packaging

- Pva glue (optional)

- Sticky tape

Step 3: Print Out and Calibrate Ruler

The first step in this build is to print out the primary and secondary scales used to create the ruler. Either grab an image off the internet or download the pdf provided:

http://www.mediafire.com/file/ije05ggxdiqrmeq/parts_diagram.pdf

You may need to calibrate the ruler, by this I mean line up the print out with an actual ruler to check that it is the right size. This could be a problem when using different A good forward thinker like myself will print out 3 or 4 slightly different sizes to cut down on wasted time, and 4 are provided in the pdf.

When you have found the calibrated set of scales, cut them out using scissors

Step 4: Print & Cut the Body Parts

A cutting pattern has been provided in the pdf below for the shape of the caliper:

http://www.mediafire.com/file/w808klf92zmzz88/vernier_caliper_project.pdf

- Cut out the shape

- attach the paper to cardboard using sellotape or a small amount of PVA glue.

- cut out the pieces

Step 5: Assembling the Parts

make sure the scales will fit onto the body before assembling the caliper, in the way shown in the GIF

In general, part A is needed to slide the primary scale across. Part B is the ‘arm’ for the primary scale. Part C&D fit above and below part A, and the secondary scale should fit on Part C. Part E and F keep parts C & D close to part A.