Ah, gad-dammit. Knew I should have saved it as an .ma file. Hmm. Sorry I've been unclear in my instructions. I've just gone through it all again just to make sure I've not missed a step. So, here's what I did, verbatim. Fixing Newton's Pendulum PART I - Align the balls ~~~~~~~~~~~~~~~~~~~~~~~~ 1) Load file 2) Using front view, select left-most sphere 3) Modify->Reset Transformations 4) Translate by 5 in Y axis PART II - Reset axii ~~~~~~~~~~~~~~~~~~~~ 1) For each sphere, move the pivot to it's center. PART III - Setting the start position ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 1) Create a locator 2) Set the ScaleX, ScaleY and ScaleZ of the locator to 1.5 in the channel box. This makes it easier to grab a hold of. 3) Move the locator to the center of the left-most sphere. 4) Move the pivot of this locator directly up until it is the same height as the top of the frame. 5) Select the locator AND the ball and set RotateZ to -45 deg. Note: This will make the ball rotate in place and the locator swing around it's pivot point. 6) Move the already-rotated ball so it's pivot lies on top of the locator you just positioned(with the -45 deg rotate). 7) Hit play. Here's the .ma file of the scene. I believe you can edit the file by hand and get maya to open it. Just change 1/all of these 3 lines to reflect the version you'd like to open it with requires maya "7.0"; fileInfo "product" "Maya Unlimited 7.0"; fileInfo "version" "7.0"; Simon