How does one make an animation of a running engine?

TimBo

Roygee said:

I recall doing this a number of years ago for a steam engine - here's a rough and ready example.

Con-rod parented to crankshaft, Piston independant body.  Two target helper objects on top tip of con-rod.  One parented to piston, one parented to con-rod.  The piston has a "track" modifier - the THO parented to the con-rod.  The con-rod has a "point at" modifier - the THO parented to the piston. 

Give the cranskshaft a spin modifier and off you go - all automatic, no keyframing :)

One problem I couldn't solve then or now is to stop the con-rod from making a -90 degree rotation at the start of the animation - hopefully someone more knowlegeable will jump in.

 

 

I like this idea but it is the same with me about the con rod flipping instantly at 0 and 180.  Weird.  Maybe someone can figure this one out.  Could it be a flaw in the program?

PhilW

msteaka said:

However Phil seeems to have a more elegant solution, I would think that would be the way to go.    

Hmm, not sure about that - I mean my physics based solutions works, but it is not very robust, I tried doubling the speed and even just that was enough to break it.  I think for a more complex engine, either keyframing or a solution based on Roygee's modifiers would be the way to go.

MarkIsSleepy

msteaka said:

I am not very familar with Youtube..It played for me so I assumed it was ok for others. I have been on Youtube but so far unable to to find the panel to correct the problem. Will try again tomorrow.  In the meantime this is a frame from the video.   

@msteaka - you need to set it to "Published" for others to be able to see it.  You usually have the option when you first upload it to have it automatically publish when it finishes loading but of you want to keep it private or forget then it loads as a private video that only you can see.  Go to the video and look for some icons underneath it - one of them should be Info and Settings, go to that, then go to the Video Manager and click Publish next to the video you want to make public.

cdordoni

TimBo said:

Roygee said:

I like this idea but it is the same with me about the con rod flipping instantly at 0 and 180.  Weird.  Maybe someone can figure this one out.  Could it be a flaw in the program?

Try changing the rotation from Quaternions to Euler Angles (unless you have already done that).

Roygee

That was the first solution I tried - no luck :)

starboard

Thanks MD02010,

I followed your instructions..It should be ok.  The only problem is that this video and some of the others I have posted were created many years ago (amazingly..almost 15 yrs.  - how time flys)  in NTSC  mini DV format.  The result is they are a little blurry and somewhat dated.  However the keyframing worked then as it does today....

DesertDude

Timbo, I turned my brain inside out trying to get this to work:

After uploading my example, YouTube helpfully pointed me to this tutorial:

I started watching, but it made my head hurt even more. It is another approach that you may find useful...

I need to take a break for a while then I'll come back with an explanation. Thanks to JoeMamma2000 and Roygee for tips and clues.

 

DUDU

DesertDude, I hoped that you would see this thread and you are there !
Your passion and your experiment for the technical scenes make me impatiently await your explanations to carry out this.
Thank you in advance !

DesertDude

DUDU said:

DesertDude, I hoped that you would see this thread and you are there !
Your passion and your experiment for the technical scenes make me impatiently await your explanations to carry out this.
Thank you in advance !

DUDU, thank you for the nice words, but you are much too generous!  99.9999% of what little I can do is only because of the Carrara community, Google and YouTube.

Meanwhile, here is an attempt at an explanation with some pictures. There are some caveats at the end because I really don't know what I am doing.

You need 3 parts - "Crankshaft" "Arm" and "Piston". You also need 3 Target Helper/Null objects.

Parent Null_001 to the "Crankshaft" and align according to the picture.
Duplicate that Null 2 more times and name them as Null_002 and Null_003 (or whatever you wish)
Move the Hot Point of the "Arm" to the same position as Null_001
The "Arm" is not parented to anything
Add 2 Bones and attach them to the "Arm". Carefully Align them with the parts you want to rotate, i.e. center them with the bottom and top cylinders of the "Arm" where you want to "pin" them.
Bone 1 Tracks Null_001 in X and Z
Bone 2 Tracks Null_003 in X only
Put a Constraint on Bone 1 and Bone 2. Bone 1 put Full Constraint, check Scale Min and Max...(and X axis to be safe). Bone 2 I used a Shaft Constaint and Locked X,Y and Z
Parent the "Piston" to Null_002.
Add Track Modifier to Null_002 towards Null_001 on Z axis only.
Add Track Modifer to "Piston" towards Bone 2 on X and Z axis.

That *should* work.

Caveats:
I have little to no experience using Constraints. I experimented and I am probably abusing them.
The pictures show Bone 2 and Bone 3...should be Bone 1 and Bone 2. I was too lazy to rename them and only realized after...and way too lazy now to make new screen grabs.
Your model may be different, so becareful with X and Y axis for Tracking behavior.
It's still possible to make this a more simple setup...maybe more experienced users can further enlight us.

Despite this "spaghetti" mess of an explanation, I hope this helps

Edited to add picture of "Arm"