Reinforcement carbon fiber plate for L75 frame
The spindle of the pulley turntables Lenco L75 is top of the range, with low tolerances, but unfortunately their hub is anchored to a frame that is not very rigid. The scarce thickness of the frame made from 2mm printed steel does not have any bending rigidity.
I noticed it when I tested the spindle’s tolerance by pressing the table at its extremities. I obtained considerable movement, not because of excessive spindle-bronze tolerance, but due to the bending of the whole frame in the area where the hub is anchored.
Thus we designed ‘support plates’ to make this critical area more rigid. A similar solution is used in designing sports cars; steel plates are placed on the suspensions struts to supply a stable and rigid geometry when external strains vary. The situation is not much different for the Lencos.
We used a CNC cut plate made from 2.5mm carbon fiber. Carbon fiber is more efficient than steel because it is more rigid with equal thickness. In order to have the same rigidity we should have used 4mm thick steel and this would interfere with the turntable.
The plate mounted with stainless steel screws and larger washers improves the situation hugely and this can be verified upon listening.
It is certainly not a radical and decisive solution such as the building of a new frame, but it is indeed a functional and economical one. Beware of imitations made from steel; they cannot have the same rigidity as carbon with equal thickness.
The kit is on sale, including screws, a carbon fiber plate and a set of widened and cut washers, at the price of 35 Euros plus postage costs.
NB: the kit ‘works’ only on L75; on L78 there are levers systems that make it impossible to use it.