Hello. I am fairly well versed using SketchUp Pro, but am new at using the Animator extension. What I am trying to do is animate the flywheel spinning along with the attached cylinder and piston.
I can get the flywheen to spin properly, and the piston to move back and forth inside the cylinder. I can even sync up the piston/cylinder to travel and rotate properly to line up with the flywheel pin at each of the four 90° positions. The problem now is how to get the piston and flywheel pin to link to each other and stay connected for the entire 360° of the flywheel while it spins.
This little project is to get better at Animator rather than trying to find the best product for this animation.
I haven’t found too many other Animator enthusiasts out there, but maybe someone could suggest an approach to this.
Its not exactly the same scenario, but this post I made a while back about animating a piston and its connecting rod will give you an idea.
It’s been a while since I did it, 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 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.
You don’t need to do all that math for animating a piston and a wheel on animator, that math is if you need a precise movement for a simulation if you’re designing pieces for a machine or an F1 car, in which case sketchup isn’t the right tool.
With animator, keyframe animator or scenes, you do it just by changing the position and rotation and adding it to the time line or scene.
Maybe you should actually attempt to create the movement using Animator liked the OP says he is trying to do and then you will be very grateful for my notes. Once you learn how to create the movement below you could then maybe apply it to an F1 Engine
Well I´m not a mechanical engineer, the animations I´ve done are either virtual tours or process of construction, but in the very hypothetical case someone asks me to design something like a gear and make precise simulation I surely be grateful for your notes but in that case I wouldn´t use Sketchup to make that simulation, probably CATIA would be the right software for that.
Wow. That was a lot of work. Thanks for the information. I won’t pretend I understand all the formulas, but I do understand what they are trying to get accomplished. However, I’m not sure if they can be translated into something that Animator understands.
Great. Did you do these using SketchUp and the Animator extension? I don’t expect anyone to actually do it for me. I’m just trying to understand the overall approach that I can dig into and learn for myself.
Hi Randy. The animation shown in my example is powered by the animator plugin and all the clues are in my post. Let me know if you need any help although I do appreciate Dave’s method is easier to implement.
Using SketchUp and the Animator extension I’ve managed to get the flywheel spinning and the piston/cylinder to pivot and extend/contract properly, but only at the cardinal points of the circle. I’ve attached the animation. Obviously the pivoting and extending need to be altered to match the pin on the flywheel. I appreciate your calculations. Even if I did plug my numbers into them I don’t understand where I would enter those results into the Animator interface. Maybe the problem is that I am using combinations of Rotation and Translation movements to move the piston and cylinder.
I’m obviously missing a big chunk of how to do this.
Thanks
Randy
I went through your notes and applied what I could. I’ve always had the measurements for offset A and B. I’ve been able to create most of what’s in your animation, with the exception of keeping the piston aligned with the Z axis. I’ve attached an animation of what I am getting. Unfortunately the vertical piston wanders from the Z axis. Is there any way of getting a copy of your model in order to see how you did it?
I didn’t keep a copy of the .skp file for the animation I posted above, but if using animators’ ‘spin’ movement rather than ‘rotate’ doesn’t work for you, I will recreate it this weekend.
Just curious. What would it take to animate the piston along with the eccentric and the steam valve ? How hard is it to keep all your ducks in a row with Animator for that. I have Animator but so far I’ve found it simpler to make the animations as I do instead.
I couldn’t be sure without experimenting. I think the animations you create are great and your method is really versatile, but my motivation for using animator is to save the crankshaft/con-rod/piston movement as a clip to be used within other more complex sequences involving the entire gear box. Im pretty sure animator can do almost anything given enough thought about the movements involved. Having said that I am currently experimenting with MSPhysics and hope to post some really good stuff at some stage
