The Acme string structure (/ˈækmiː/ack-mee). The Acme string was produced at some point in the second 50% of the nineteenth century as a profile appropriate to power screws that has different focal points over the square thread,[a] which had been the type of decision until then. It is less demanding to cut by means of either single-point threading or bite the dust than the square string is (on account of the last's shape requires apparatus bit or pass on tooth geometry that is inadequately suited to cutting); it wears superior to anything square (in light of the fact that the wear can be made up for); it is more grounded than a similarly measured square string; and it makes for smoother engagement of the half nuts on a machine leadscrew than square does.[2][3]

The trapezoidal metric string structure is like the Acme string structure, aside from the string point is 30°.[4][5][6] It is arranged by DIN 103.[7] Although metric screw strings are for the most part more predominant worldwide than royal strings, the Acme string is extremely normal around the world, and might be more generally utilized than the trapezoidal metric string. This is not astounding, as makers today are generally equipped for making whichever strings (metric or royal) are best for any given application (taking into account client desires or tooling accessibility). It might be that the tooling for Acme strings has been so prevailing (contrasted with trapezoidal metric) that clients tend to need Acme strings for force screws paying little respect to metric measures utilized somewhere else as a part of the item.