For beginners, I will explain what is shaft turndown pool cue and then explain why intermediate and experts players turndown a shaft.
What is a Shaft?
For a two-piece or three-piece cue stick the part of the cue closer to the cue tip is the shaft.
This part of the cue stick is conical that is the part where it joins the butt is thicker and the other end is thinner. From the joint to the cue tip the shaft becomes thinner. This process of becoming thinner is called tapering.
The most common cue tip diameter is 13mm which can go as low as 11.75mm.
What is Turned down Shaft?
The shaft whose tapering is further lowered from butt joint to the cue tip is called turning down of the shaft tapering.
Why Are Shafts Turned Down?
In order to get more accuracy with the shots. A cue tip that is smaller in size allows the experienced players to hit the cue ball at more precise position on the ball. But there is a downside to this as well, all players are not the same and some mistake more than the other.
Pool is a game of fraction, a slight mishit on the cue ball then the intended spot results in an unintended spin on the cue ball. Intermediate level players are more likely to suffer from this then expert players who have better techniques and play the game more consistently.
If someone has a good technique on holding a pool cue then a turned down tapering of a pool cue would help. You will find more experienced players lowering the tapering because they know what they are doing. If you are a beginner then it would be a better idea to invest in a good pool cue rather then lowering the tapering.
Another reason why shafts are turned down is because of a rough transition. Often players upgrade or change their pool cue to a higher cue tip because they feel that a bigger cue tip would help in hitting the cue ball straight. The problem happens when they find the shaft to thick to play with a closed bridge. As a result, the temptation is very high to turndown the shaft.
CONSEQUENCES OF TURNING DOWN A SHAFT
You can void your shaft warranty. Altering the taper can change what the manufacturer sent you which would rightfully void the shaft warranty. Before you plan to do the tapering you should know exactly what you are about to do. Too much stress can change the tapering more then you have planned. It is better to get it done through an expert because you can not practice this with a cheaper pool cue because materials between a cheaper and expensive shaft can vary and the same force can change the amount of material removed.
Even if you have correctly reduced the tapering then it can alter the properties of the shaft. The balance point of the cue can move and you can lose the low deflection of the stick because the inner part of a low deflection stick is hollow and filled with other material.
If turning down of tapering is a must then I would suggest that you do it only for non-deflective pure maple shafts.
If you have a carbon shaft or a low deflection shaft then I suggest that you sell it up and buy a new shaft with lower tapering. Good manufacturers have lower tapering shafts within same model or similar shafts with lower tapering. For example, predator revo shaft is available in 3 different taperings.