I experimented with various oscillations, but they are disabled in the file that I uploaded (I think, this was my intention anyway). My intuition told me that a saw-tooth oscillation coupled with a sine-in or sine-out movement would produce 1/2 rotation (maybe even full rotation), but I could not get it very close. I also experimented with sinusoidal oscillation for the up-down movement (which should be exactly what’s wanted) coupled with no easing on the corresponding movement, but I could not get it to work very well. I may have had some stage of the nesting wrong or some other “simple” error but I couldn’t figure it out within the tolerance of my patience, so I switched off the oscillation and used sine-in/out easing on 1/4 rotation sequences.
I think you won’t be able to build something accurate with animator (at least until I implement kinematic movements).
You should try MSPhysics by Anton S, which is based on physical simulation and can generate an animated video.
Thank you very much - I think if I employ your solution but attach the big end bearing to the con-rod rather than the crankshaft the result will appear near perfect.
Thank you for your advice, and also for creating such an interesting and versatile plugin 
I promise this is my final post on the con-rod movement, as I think, after lots of help, I finally understand it 
The final trick for me was to calculate the actual angle of the con-rod when the crank hits 90 degrees plus the vertical offset of the little end at the same point and enter those values manually. For Easing I used OutSine & Insine only with no Oscillation values.
The result is pretty darn close and I am happy to move on:
Feeling pleased today - I’ve just managed to purchase a set of original S3 crank cases on eBay.
I have a Faro 3D laser scanner so I will be able to scan them and import the Point Cloud into SketchUp to model them accurately so the crank case sizes will be spot on.
I tried explaining to my wife why I had to buy this lump of dirty, oily, 45 year old aluminium. She didn’t get it at all, and thinks I’m mad
That’s the risk of taking a wife.
Well, aren’t you? You keep it on the dining table, of course.
Love your project. I have never driven a motorbike but my driving license entitles me to do that and kill myself in the first curve.
Hi Kevin
Jo Here
That a task you’ve set yourself .
I’d start with the Haynes manual.
it you are creating it from scratch and also.
look up Engin drawings . See link .
Hope this helps
Best
Jo
Thanks Jo - much appreciated 
OMG - look what’s arrived in the post today 
Can’t wait to scan this beauty tomorrow and start modelling it.
Some days are a success, but today was definitely a failure.
I spent hours doing 13 separate scans today (15 minutes each) of the lower crankcase making sure I got it from every angle, but the resulting point cloud was unrecognisable. I use the scanner all the time for scanning buildings and I thought it only had 4 settings which are outdoor >20M, 20M+, and indoor >10M, 10M+, so I used indoor >10M but when I imported the point cloud into SketchUp it was unrecognisable. I’ve just checked the settings and found another one called ‘Object HD’ which sounds more promising but each scan takes 1 hour 58 minutes. I think I had better study the manual again before doing any more scans.
A quick update on my project. I tried multiple times to get a decent laser scan of the crank cases without success - I did find a setting that gave a reasonable result, but as each scan at that setting takes about 2 hours and I recon I need 12 scans minimum that isn’t going to happen. My very expensive scanner obviously wasn’t designed to scan small things! I’ve sent them off now to be de-greased and shot blasted so that I can have them on my desk and measure them by hand without getting everything filthy. Afterwards I think they will look really nice hanging on my office wall
I have not had to do with point clouds very many times, but I would have thought them to be quite good enough for something like this where the result doesn’t have to be accurate to the last micrometer. Some years ago I looked at a series of external scans of a quite large building. It was rather insane - I was almost able to see what make was the ballpoint pen someone had dropped on the pavement in front.
I find my scanner gives incredible detail for objects further away than say 3 metres, but not for anything much closer - it was obviously designed for scanning buildings which is what I bought it for.
I actually had the crank cases hanging from the ceiling in my office to scan them 360 degrees - so the scanner was probably less than a metre away. To be honest I got MUCH better results using photogrammetry which is something I had never heard about before, but it was really interesting to experiment with:
Getting Started with Photogrammetry Using Your Cell Phone - YouTube
I’m really looking forward to modelling the crank cases from hand measurement’s now, especially after a powder coating company I deal with offered to clean and shot blast them for me.
Just collected these freshly de-greased and shot blasted beauties! Cannot wait to to get this motor up and running
Been thinking about this on this on and off for the past year having got stuck with the animation of multiple connecting rods and pistons. I was able to animate 1 cylinder successfully but everything went crazy as soon as I tried to do 3 cylinders despite my repeated attempts. I finally realised I had to use the ‘spin’ movement in animator rather than ‘rotate’ and then everything worked.
I’ve been experimenting with various ways to model the crankcase and think I’ve finally nailed it, but more of that later.
Brother I have been trying like hell to get the animation off a crank shaft going with my model. Could you please please tell me how you were able to achieve this. Thank you so much!!
The interface top left tells me it’s Fredo6 Animator (I recognised it, you didn’t miss the name)
it’s free until the end of the year, perfect time to get on it 
Hi 5276johnsonst
It’s been a while since I did this, but luckily I kept my notes which are shown below:
Choose variables ‘R’ & ‘C’ for your own setup:
‘R’ is the throw of the big end i.e. the distance from the centre of the crankshaft to the centre of the big end bearing.
‘C’ is the distance between the big end and small end bearing centres.
Using ‘R’ & ‘C’ calculate Offset A & Offset B (see the example in my notes) which is the vertical movement of the piston and small end bearing during each 90-degree rotation of the crankshaft, i.e. they both descend by Offset A during the first 90 degrees rotation from top dead centre and Offset B during the second 90 degrees before ascending by B then A.
Next, calculate the angle from vertical that the con rod spins about the small end centre during each 90 degrees of rotation (using the values C = 90 & R = 33 in my example the Sin of the angle will equal ‘R’/‘C’ i.e. 33/90 so the angle is 21.51 degrees
Then using Fredo 6 Animator as spotted by @ateliernab you can recreate this movement. The big end of the con rod spins back and forth about the small end centre by 21.51 degrees during each 90 degrees of rotation while the piston and the small end move vertically by Offset A & Offset B.
It may take a bit of getting your head around, but its important to know that the movements are not linear. The spin of the con rod about the small end changes from outsine to insine to outsine to insine during each 90 degrees of rotation while the vertical movement of the small end and the piston changes from insine to outsine to insine then outsine.
You will find it all starts to make sense if you give it a go.
Best of luck with it
