Spring balance for heavier loads

Fasten a chair or automobile cushion spring to a flat piece of wood that will dish up as base to the instrument. As scale pan, use a large tin lid or plate. Fix this to the top of the spring. If it is not possible to use solder for this purpose, the scale pan can be secured by fine wire passed by double holes punched by it in convenient positions.

Attach two vertical laths to the base. These act as guides to the scale pan. Make graduations on these guides when loads of 0.5,1, 2, etc., kilograms are placed on the scale pan. Wine bottles filled with water make suitable calculates of litres, etc., and having of course, the equivalent weights in kilograms.