A flexible driveshaft includes a proximal coupler and a distal coupler each configured to couple to a respective component of an instrument, and a flexible shaft having a proximal end connected to the proximal coupler, a distal end connected to the distal coupler, and a longitudinal axis. The flexible shaft may include a sleeve, and a core having a first end and a second end. The core is housed within the sleeve. The flexible shaft also includes a plurality of coils arranged around the longitudinal axis in at least one layer.