Sunday, 29 June 2014

What is the Tween Machine?

Below is a simple guide to installing and using the TweenMachine plugin, one of the most useful free plugins available to Maya animators.

The free TweenMachine plugin, created by Justin Barrett, helps animators to create breakdown poses in Maya on stepped curves. It's a time saving tool that takes much of the labour out of breaking down your poses - once you are happy with the timing of the main blocking of your animation.

What is the tweenMachine?
The tweenMachine is a free Maya plugin designed to simplify the process of creating breakdown poses between your key poses.

How do you download the tweenMachine plugin?
You can find the free plugin here:

How do you use it?
To animate with the Tween Machine, watch the video below

Who created it?
The tweenMachine was created by Justin Barrett.

How do you install it?
The tweenMachin comes with a Read Me file, which you should definitely read.

To install the tweenMachine,  first find these files:

Copy the files into your scripts folder in Maya. The path should look something like this: username/myDocuments/maya/2016/scripts
You can also copy the files into any other scripts folders you see - such as older versions of Maya - while you are there.

Once you have copied the files into your Maya scripts folder, open Maya.

Now open up the script editor (bottom right hand corner of yourr screen) and type this in the MEL (not Python) command line: tweenMachine. This should launch tween machine.

In the script editor, copy the command, and create a shelf tab so you can use the tweenMachine any time you like. Name it tween, or TM

Click on the shelf tab to activate the tweenMachine. A pop-up slider should appear:

Why won't it install?
If the tween Machine won't install, work through this checklist. Have you:

  1. copied the program files into your scripts folder? Remember that you must copy the individual program files into the scripts folder. If you just copy the folder which contains the files, the tweenMachine may not work.
  2. copied the program files into other scripts folder, such as Maya 2015 and Maya 2016 subfolders? Copy the files into any scripts folders you can see.
  3. saved your scene and re-opened Maya? Re-opening Maya forces the software to refresh itself.
  4. closed Maya and re-started it again?
  5. re-booted your computer?

Hopefully one of these methods will make the tween machine work.

How do you test it out?
To test the tweenMachine, first create some break down poses on a simple moving object, such as a sphere.

1. Create a sphere. Create/polygon primitives/sphere.
2. Move the sphere to one end of the grid, and set a keyframe on it
3. Click on the preferences tab in Maya, and set your animation curves to stepped curves, not spline.
4. Back in your timeline, go to frame 25. In the viewport, move the sphere to the other end of the grid, and set a key frame. Press play. You should now see the sphere move, but in a very staccato fashion.
5. Go to frame 13 in your time line. Set a keyframe on the sphere, and click on the tweenMachine button. Use the slider on the tweenMachine to adjust the position of the breakdown pose. The slider allows you to favour one key pose over another.

Ok, got it. Now, how do I use it for proper animation?
Now use the tweenMachine to create break down poses on a complex human biped.

1. Import a human biped, such as the Morpheus or Max rig.

2. Create two poses, one at frame 1, and a second at frame 25, following the thumbnails below.

3. Now select all the controls, and set a keyframe at frame 13. Click on the tweenMachine tab, and use the slider to adjust the spacing of the breakdown position.

4. Once you have done your pose at frame 13, go ahead and add breakdown poses at frame 5, 9, 17 and 21, using the tweenMachine.

In conclusion:

What the tweenMachine does is allow you to set breakdown positions on all the control curves, without having to manipulate individual controls one by one. It saves a huge amount of time on production.


For more information on finding work in the animation and visual effects business, read our post on how to find a job in the animation industry, and check out our post about what not to do at a job interview. Also see our post on starting your own small animation business, learn how to create an invoice, and see how we are helping our students find work through our film co-operative Nano Films.  Download the free Escape Studios Careers in VFX Handbook. Take a look at how can help you find a job, and read our piece about how to survive as a freelance animator. Also, find out what Cinesite look for in a student's demo reel, and read our post on setting up your own animation business.


  1. please help me i am traying same steps to install tween machine in maya 2013 but its not working error is lie that //error prosuder code somthing
    please any one no this ow to fix please help me......

    1. I just stumbled across this comment from last year. Sorry to hear that you had trouble getting it to work. Is it still not working, or did you find a solution? If not, please contact me directly. Follow the link in the article above to my site, then fill out the form on the Contact page.

    2. Thanks Justin! The Tween Machine is a wonderful tool!

  2. Hi Ravikumar, sorry you are having trouble. Follow all the steps super carefully and you should get there in the end., It is a bit buggy.

  3. Hi Justin I have tried following your steps but not working, Do you have any Recorded video how to install TM.


    1. Just to clarify, Pritam, I'm not the author of this article (though somehow I was notified of this comment, possibly because of my earlier comment). Unfortunately I never recorded a video re: installation of tweenMachine, but managed to find one on YouTube after a quick search:

      Also be aware that I turned over all tweenMachine development to Alex Widener a few months ago, so the tool is no longer hosted on my site. Here's its new home: