Hi all,
I have a series of cogs that form a machine. They are controlled by an expresso using a master cog and math:multiply based on the number of teeth on each cog. When i manually rotate the master cog, it works. it also works when i key frame rotation up to 360 degrees. However i need it to rotate 30 times in 30 seconds. If i add a key frame with 10800 degrees of rotation some of the cogs rotate erratically. does anyone have any clue or suggestions please. thank you.
I animated the Spline #1 R.B value, and set it to linear interpolation. Yes, the file shows only 1080º.
What I can see at 10800º is an effect where it rotates too fast and provides the illusion of rotating right and then not. With motion blur, this should be clear.
Perhaps have a look at the Checker-box that I have applied, it even is at 1080º too fast on end.
Sorry for this but please will explain the difference between 10800 degrees (i.e. 360 degrees *30) and entering 188.496? I’ve tried that but get half a rotation of my master cog?
In the Xpresso file, the parameter in the Constant node needs to be in Radians. This means 360º is expressed in two PI. [6.28…] In the Object >Attribute Manager> Rotation fields, Degree is expected. If you place radians values there (while degree is expected), it will be much slower.
In post #4, I have added one file, your file. This morning I was, As I wrote in a rush to be on time for the Funeral. So I shared only the Xpresso example.
Your file is now added as well in post #4. Please got to frame 500 and render motion blur, you will see that most teeth are just not visible anymore.
The editor shows per frame a single frozen representation of the scene, no motion blur. You have seen it in movies when the wheel seems to move backward. Then stops even and moves forward later on. This has to do with the frame rate and the rotational speed. Google, “Why do car wheels spin backward on video?” and find a more extensive collection explaining the ‘secret’.
When you play just the editor view, you can see the change of the tooth representation.
I hope that explains it, if not, please let me know, I will then try to set up a better example.
Thanks so much for this. I understand the idea of the wheels appearing to move backwards. I don’t understand your first point about radians v degrees. What do you mean by the constant node parameter. And how do we place radiance value in the rotation field when it simply makes it degrees? I get that the solution is just to slow the whole thing down a lot but it would be great to have a better understanding as well.
Initially, I had no file, and typically, I do not try to guess what could have happened. I should not have done so, as I see how those guesses produce even more confusion. I think of guessing, instead of examining a scene file, as an act of professionalism, as it takes time to go through the guess while dealing with a problem. Sorry that I even tried, my fault. I usually request a scene file, it is clear to me after 15 years answering Cinema 4D questions, that I should know better. Much better than doing that guess-work thingy again. Please accept my apology. (It drives me nuts in other places when a long series of guess-work is done, with no real result, instead of opening the file in question and find facts. Yes, sometimes one can’t share the file, then an example file must do.
In Xpresso we need radians (normally), In the standard interface (outside of Xpresso) we need Degree, for any rotational parameter. If you place this otherwise, the expected speed will not match.
Again, let me know if there is anything not clear, and I will find something else to communicate about this.
The Splines in your scene have a lot of points, I guess half of the amount or even a quarter would have been sufficient, but this is of course only true if the camera takes no close-ups of the teeth. So toss this idea if the camera work requires it. Since the wheels are made editable, there is not really an options to reduce this quickly.
Some adjustments might help to get a more fluid preview. In this case, setting a lower ‘Level of Detail” isn’t helping, nor does the idea to set the splines to Linear and no interpolation.
To have the settings to Play All Frames set to on might slows down the preview. You can check that by setting the FPS to 500 and toggle this (Play all Frames) on and off. It should show clearly. If it affects your 30FPS project time is based on your hardware, of course, something, I might not say anything about it, as I would need to have it.
Thank you for your reply. Sorry i have another issue with the cogs. the cogs still do not rotating properly. i have added a degree to be able to change the radians to radians however at 00.01.07 (frame 32 )the result changed from -203.414 to -0.495 on 00.01.08 (frame 33 ) this happens on cog 4 and 5 however before this jump happens it goes up steadily. i only have problems with cogs that i have a parent and child relationship, how do i fix it so it does not have the gutter in the cogs. you can also see and example of this at the start of the animation.
Please have a look at your Cineversity Private messages.
I just do not click on links that I don’t know where they lead me. Sorry. Dropbox, Amazon, Google, Adobe, or Apple. Anything else, for security reasons, not at all. Thanks for understanding.
Inside of a Radiance based calculation, there is no need to convert back and fore.
Please note how X-Manager (Xpresso Editor) is sorted, top to button, as this sequence is crucial (Priorities)more often than not.
The Extrude is rotated, not the spline, it will prevent mesh problems. It also allows setting the Cogwheels to a P.R value, that adjusts the connection to the neighbors.
Please allow for a moment to set up an alternative file.
The Cogwheels are adjustable, and the teeth are used for calculations, which will be more precise.
P.S.: My personal way of setting up cogwheels has been since long (20 years by now?) based on tooth-count. As this is the most relative ratio among all wheels. Yes, the diameter would be the one I would have used back in time in my early education in metal-work.
For visualization, the teeth count is appropriate and much easier to handle in Xpresso. Please note that I turned every second wheel in the chain R.H:180º. Which means I don’t have even to bother in which direction it turns.
To have the Teeth calculation separate from the Angle allows from my point of view for better precision and management in the Xpresso setup.
