yeah, they are actually pretty easy. Describing them... not so easy. Here's a go:
with your left hand do a 1 beat. Probably best to do it out to your side in wallplane while facing some mirrored surface. May wanna hold it out from your body a bit if you have long staffs.
this is the "wheel" of the train that you are making. Ever look at a train? ever see the drive wheel? you got this metal rod that has one end attached to the wheel and that rotates around with it. The other end is attached to another rod that only moves linearly (forward and back). So in this case, your other staff (the right hand one) is going to be the first metal rod (attached to the wheel). And one end of the the right hand staff is going to follow one end of your left staff. However your right hand staff is NOT going to make "spin" circles. While the 1 end (we'll say the top end, which is the side extending from the top of your fist) follows the left staff, the bottom end moves in a straight line in a left to right to left to right etc motion. Essentially the bottom end of your right staff acts as the pivot point for the right staff.
All in all it looks like the fill drive wheel setup of a train, one wheel with a rod that follows it around.
Another good way that may work for you is to think of a piston in a car engine. One end moves linearly, the other moves in a circle.
Then you can get into R-types and other crazy mess that is strictly for nerds but way fun once you understand it ;-)
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I once learned every move that there was,
Every style, Every technique.
Then I woke up, and forgot it all,
So now I struggle to dream.