This is a taiji ball with its training table.
When I say "Taiji Ball", I just follow what people usually call it nowadays. Training with a wooden ball / stone ball is not monopolised by Taiji. The discussion below relates to training exercises from an internal martial art / taiji perspective.
This taiji ball is made of solid wood and weighs 7 pounds. It is made from a single piece of wood.
For advanced training, some martial artists use balls made of stone. Stone balls are heavy. The weight of a stone ball varies from 30 to 50 pounds.
A high quality wooden ball is costly and is usually much more expensive than a stone ball. A taiji ball made of combined wood is cheaper.
If a wooden ball is not readily available, a beginner can use a basket ball as a temporary substitution. However, one must note that a heavy ball is essential in developing the internal power. An alternative is to get a no holes bowling ball. Stone ball is good but is not for a beginner, who should always resist the temptation to use a stone ball.
I note that some people talk about the importance of the material from which the ball is made, saying that certain material is "chi" friendly. I have no comment on this. My view is that so long as the material does not hinder the rolling process or if it is not too heavy for your physical capability, it is useable.
There is no, and should not be any, "standard" size or "standard" weight. Imagine the absurdity of asking a small built and weak person to train with a large size stone ball; or asked a big guy to train with a small size and light weight ball.
I also note that there are "taiji balls" painted with colourful "taiji" symbols. Other than price, the colourful symbol does not and will not add any value to your training - know what you need and get what you need.
Back to the first photo. The training table has a concave surface. It was originally designed for the elderly to practise ball rolling exercise. The concave surface of the training table helps to control the movement of the taiji ball so that it will not roll outside the table area and drop onto the ground. The exercise is simple, you put the training table on a desk and the taiji ball on the training table. You then use your hand(s) (single or both) to roll the wooden ball, in a clockwise or anti-clockwise direction. It is said that the exercise assists the elderly to relax and increases the flexibility of their joints.
Internal martial art training exercises are complicated as there are various methods to roll the ball. A beginner can, however, take advantage of the concave surface of the training table for initial training. Following the ball's motion, a beginner learns how to do circular movements correctly. The ball's motion will rectify your motion. The training also assists a beginner to strengthen his torsos, and enhance the coordination of his mind and body. It will also enhance the beginner's sensitivity and the ability to detect the other's "centre".
After passing the initial training stage, a beginner can discard the concave training table and roll the ball on the desk top direct. It requires greater skill to roll the taiji ball on a flat platform. A higher level of control is also required as it is easy to drop the ball onto the ground and hurt your feet and / or damage your floor (this also destroys the taiji ball). When rolling the ball, the practitioner should imagine that his internal energy is flowing out like water from his "dantin" to his hand and use the energy, instead of the arm's muscles, to roll the ball. It is not necessary to use the palm to roll the taiji ball. One contact point is sufficient to rotate the taiji ball if internal power is used.
The next stage is to roll two balls at the same time, each hand controlling one ball.
It has to be noted that, it is not safe to roll a taiji ball (or two taiji balls at the same time) on the desk top without any precautionary measures. Some people put a towel on the desk but this will limit the rolling speed of the ball. Personally, I use a rectangular wooden plate with railing to do the exercise.
Apart from table top rolling, there are other rolling exercises such as rolling the ball on the wall or on edges of table. Use a basket ball for these exercises- don't take the risk to use a wooden ball or stone ball. In addition, there are some taiji ball standing exercises. A practitioner holds the taiji ball in his hands and performs various sets of specially designed circular movements - a wooden ball, instead of a stone ball, should be used. Through these exercises, a practitioner learns how to transmit internal force through circular movements, taking advantage of the centripetal force and the centrifugal force.
The training is not for muscles building. A practitioner should not fall into the trap of the Strong Man Principle. That's why it is not desirable to train with a heavy stone ball at the initial stage - one will even get hurt if his body is not fit enough for the stone ball.
The purpose of the training is to use external movements to activate internal movements - It is very difficult, if not impossible, to activate internal movements by practising empty-hand forms alone. You need to ignite your internal energy before it can be developed into internal power.
The taiji ball is a catalyst.
Some Training Tips:
(1) Do the table-top double hands ball rolling exercise. Once you have strong "chi" feeling in the arms, stop the ball rolling exercise. Do the Taiji Form whilst the "chi" feeling is subsisting. Compare the quality of the form exercise with that without the assistance of the ball rolling. How does it feel?
(2) Do the table-top double hands ball rolling exercise as a warm up before you practice push hand exercises with your training partner. How does it feel?
[Last Edit - 11.06.2011]