The late-model 4L , manufactured from the mid 1930s into the 1940s , showed numerous improvements over the first version with the top slide given greater travel and the tailstock provided with a longer and more robust casting. However, the most significant alterations were to the bed and saddle with the latter being thicker over its centre section and with very long arms added to its left-hand side. The was bed altered so that the ways ran on past the front and back of the headstock so proving greatly improved support for the cutting tool as it neared the spindle nose. That part of the bed abutting the headstock was braced by the addition of a large triangulated section on the underside, headstock given a more robust spindle, running in larger diameter bearing, and the backgears increased in size to cope with heavier work. The 3-step pulley was reversed, to bring the largest diameter to the left, and the arrangement for engaging backgear - previously rather fiddly - redesigned for simpler and more certain operation. The 4L illustrated below is fitted to an underdrive stand, the cost of which (if other Boley lists are a safe guide), would have nearly doubled the price of the basic machine.