Sep 26, 2010· Ive been thinking of building a small jaw crusher for the past 3 months and decided to made a very small one today to see if it would work. The jaw plates are 1/4" steel 4 1/2 inches wide and 9 inches tall. ... small rock crusher. ... Belt driven crank and a large flywheel. I think ill mount the crank on bushings rather than bearings.