V0.21 PartDesign/Assembly4 V0.12.4--Atkinson Differential Engine--Update

[ppemawm]

Can you help me to move forward?

Please see the attached revised file which follows the suggested directions in my previous post.

ASM_Atkinson_Masselottes428-1.FCStd

(601.44 KiB) Downloaded 63 times

Rotation is the independent variable.

The weight arm variable is a function of rotation such that it reaches maximum in 360 deg. This actuates the weight arm LCS_015 about its Z axis.

The Skt_Mvt001 containing the sketch is attached to the Parent Assembly.

Each weight arm is attached to 19's HoleAxis_5 which itself it attached to the rotating axle.

Keeping everything in one file makes life easier.

Screenshot 2023-05-08 195025.jpg (222.06 KiB) Viewed 1714 times

Please do not hesitate with any questions or comments about the attached file. Hopefully, it accomplishes what you were trying to do.

[Bernard19]

@ppemawm Hi,
Big change in file structure. Indeed it is much better to keep only one file.
I note that with Part, we do not only associate parts, a file is therefore possible.
My error seemed to be a misplacement of flyweight arm 17. It had to be attached at 19.

The way is still long. But I'm beginning to understand the hierarchy of this assembly combining displacement and rotation.
In Model/Variables/Angle_ weights = rotation/ 18.46.
What does 18.46 represent?
You are too strong. Thanks again

[Bernard19]

How did you turn the Skt_Mvt file into a New Part in the Parts folder?
I was thinking of just dragging the file but that doesn't work.

What is the difference between <<Sketchxx>> and Stechxx in a formula?

[ppemawm]

Big change in file structure. Indeed it is much better to keep only one file.

At least in the beginning. Once you have some experience then similar actions can be developed in sub-assemblies residing in a top assembly. My original post shows this using a master variable(s) that can be used in any file in the assembly.

In Model/Variables/Angle_ weights = rotation/ 18.46.
What does 18.46 represent?

Sorry, that was too cryptic. It is actually rotation*19.5/360 which means that the angle of the weight arms is linear with the axle rotation such that it reaches maximum (19.5 deg) at one full rotation of the axle (360 deg). Many other possibilities depend only on the limit of your imagination.

How did you turn the Skt_Mvt file 'Part container' into a New Part in the Parts folder?
I was thinking of just dragging the file but that doesn't work.

EDIT
Hmmm, seems to work OK for me. Have both files open. Select the file to drag from then select the Part Container and drop it onto the file name of the receiving file. Then you can drag/drop into into the Parts folder. You File>Merge Project a complete file but it may bring baggage that you do not want.

What is the difference between <<Sketchxx>> and Stechxx in a formula?

The former is correct and the latter is an error or maybe a translation? Basically, I do not know.

[Zolko]

What is the difference between <<Sketchxx>> and Stechxx in a formula?

The former is correct and the latter is an error or maybe a translation? Basically, I do not know.

<<Sketchxx>> references the label and Stechxx the name. Names are unique in FreeCAD while labels are not, therefore I always use names in formulas.

[Bernard19]

Hi,
I have some misunderstanding of language so? I revise my English at the same time.
I made this little video to see the movement of a file to ASM4
https://drive.google.com/file/d/1uigKnm ... sp=sharing
I hope the file will open
Thank you for always being there to support me. I hope I don't delay you too much in your activities.

[Bernard19]

After watching the short film, is this the right way to move the file or how should I do?

[ppemawm]

If you want to copy a Body from one file into another file and insert it as a link in an assembly: Yes.
You do not actually need the Part container.

[Bernard19]

Hello,
I took a little break on this project because I couldn't reproduce the movement of the weight.
I made a list to enumerate the actions and the results in order to arrive at the solution.
Between the badly oriented LCS, bad links, incomplete relations, not to mention the formulas, in short I accumulated the worries and as the movement of the weight block is complex, it was not easy to find a viable track. By dint of insisting I got the result. By the way, thank you for the formula. I think that soon we will have to revise the trigonometry.(sin/cos).
My roadmap is that it is necessary to position the local LCS then the links while checking the movement and as long as it is not good we do not go further. Once it is Ok, we integrate the next part And so on.
So now the weight block is integrated into the frame.
For operation I can't recall the rotation variable of the flyweight block from the built block. Is it possible to do this? With the animate icon, I call the weights/rotation block and it works.
My idea is as there will be multiple animations would be to have a single command that operates everything.
Next step the pistons...
https://drive.google.com/file/d/1u1Ct4_ ... sp=sharing
https://drive.google.com/file/d/1AcfD-K ... sp=sharing

[ppemawm]

I did a quick review of your files and must say that they look good. The subassembly is now corrected including the variables needed to define the degrees of freedom for proper movement. Your flywheel is a nice touch of detail.

My roadmap is that it is necessary to position the local LCS then the links while checking the movement and as long as it is not good we do not go further. Once it is Ok, we integrate the next part And so on.

That is why is is important to think through the assembly process before ever starting the model especially if some of the bodies need to be able to move. Placing the first sketch and feature of a new Assembly4 body at the default LCS will determine how easy and clean it will be to assemble. If you assemble the body before creating the sketch then you can easily see how it interfaces with its mating body.

For operation I can't recall the rotation variable of the flyweight block from the built block. Is it possible to do this?

You do not actually need a variable in the top assembly file now since you have combined the rotation and weight arm operation in the sub-assembly file. When you animate in the top assembly file choose the the sub-assembly document and its independent variable so that you can see the motion in the context of the whole assembly.

My idea is as there will be multiple animations would be to have a single command that operates everything

A convenient single independent variable is "time" since every motion can be defined in terms of this "master" variable as briefly explained in my original post. E.g. let's say that you want to run the simulation for 100 secs and you want the axle to rotate two times during that period of time. Then, rotation = 2*360*time/100. When animating, choose the time variable from 0 to 100.