The Hip-N-Shoulder-Flip Test
When you first believe the figure is done, you are ready to do the hip-and-shoulder-flip test. You believe you are almost done but the hard work is just about to begin.
The hip-n-shoulder-flip test is the key for correct performance. In the following I am going to explain how a correct hip-n-shoulder-flip should look like.
In short this test consists of two flips: a shoulder-flip and a hip-flip and it is performed on a flat surface. If the hip-n-shoulder flip is carried out exactly right then you are ready to try the third flip on the stairs (step-flip). I am almost sure that a correct hip-n-shoulder-flip will ensure a correct step-flip and if the hip-n-shoulder-flip is not right, you can definitely be sure the step-flip won't be right either.
1) Set the figure up on a flat surface. Body tilted a bit forward, arms down. He should stand freely but only a little push backward should be enough to start the move. If he starts to move without the push, he still could perform well. So the free standing is not the most important criterion, but an encouraging sign.
The starting position for the test.
2) After the push, he start the hip-flip. (The torso turns back on the hip axis.)
Barry explains the movement pretty well, I just add a little extra.
"The cords are tensioned so they are taught when the torso is horizontal." The torso doesn't need to be exactly horizontal.
In this series of pictures, you can see that as I lower the torso with my left hand, the arms move forward because the string pulls them. Between the second and third picture, the arms fall dawn. On the third picture, only my thumb prevents it from falling.
One very important addition to this moment is the bouncing back. When the arms fall, they hit the peg and bounce back upwards. There was no way I could eliminate this bouncing but it turned out that eliminating it is not necessary. (I tried to put some rubber or felt pieces on the pegs but it still bounced back.) So, in a correct move, the arms bounce back and fall down again. Then, there is a momentary stop and the balls start rolling down inside. This momentary stop is what you must achieve! The best way to manipulate it is by the string length. If the string is too short, there won't be time for the bouncing and the body starts to rotate too soon. In this case the movement will be too fast and almost surely will fall from the step. If the string is too long it won't pull the arms in time and he just falls on his head. A few millimeters in length (or even just one) matters! For the correct hip-n-shoulder-flip the right string length is one of the most important key.
It is very important to slow the hip-flip down and achieve the momentary stop. Beside manipulating the string length, I also tried two other things, but none of them worked well. I tried to extend the pipe downward toward the bottom of the torso. I thought this would give more weight to the bottom and a longer track for the balls and consequently it would extend the balls' rolling time. It did not give a good result. So Barry was accurate regarding the pipe length.
Downward extension of the pipe did not give a significantly better result.
The other way I tried to slow down the hip-flip was making the torso's backward angle less, so the balls would roll down slower on a less steep angle.
In this picture you can see how the hands don't touch the ground as opposed to Barry's drawings. One reason for this is the smaller angle the torso leans back. (In other word the head is higher up.) This didn't give a significant improvement in the movement.
3) In the following description of the movements we can just follow Barry.
The hip-n-shoulder-flip test should be done on a flat surface not on a step as on the last picture.
4) Somewhere between these last two pictures the string should be taught again in order to pull the legs over. In fact, you should set the string length in this position. I mean, set the figure in this position and tighten the string now. Then it should pull just about right.
You should also put some weight on the front, on the head, neck and chest area. (As I described it in the Weight section.) Without the weight he just stops with legs upwards. So add weight little by little and see which is the smallest weight needed to do the shoulder-flip. The weight is needed to lift and turn the legs.
The weight and the string length are strongly interrelated. Observe your figure in the last two pictures' position. As the body turns, it pulls the string, which raps around the shoulder pulley (spacer) and it pulls the legs upward. (This is not well seen on the picture.) This is the key moment. If the string is pulled too soon the figure won't have enough momentum to turn around the shoulders because the legs are lifted up too much. So the legs should be lifted up (that is straightened) only when the body is already falling down and not while it is still raising. At the same time this is the key to slow down the shoulder-flip. The shoulder-flip must be slowed down to do the step-flip (the third flip later) correctly. The way to slow down the shoulder-flip is to find the right tension for the string to pull the legs up just in the right moment. (But don't forget the string tension is also key for the hip-flip.) I must correct myself. Too slow movement won't always work. You need a little momentum to get through the slow points. So you must experiment to find just the right speed. A longer string means faster speed. A shorter string means slower speed. But a longer string also allows a better bouncing back of the arms so it helps for a momentary stop before the shoulder flip. So a longer string might not necessary give faster speed. Things aren't very straightforward.