RE: How thick is 2-56 pushrods in mertic system?
According to my calculations, it's a little more than 2 mm.
The major diameter of a 2-56 rod is about 0.086". Multiply this by 25.4, (the number of mm to an inch), and I get 2.1844 mm. Now remember this is the OUTSIDE diameter of the THREADS. The inside diameter, (the valley), is about 0.065", or 1.651 mm.
So actually, a 2-56 rod should be a little larger than 2 mm.