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

[Bernard19]

Hello,
Resumption of file SKt weight v3. I'm tearing my hair out. I can't find why when the triggers the angle variable of the animation, the arm/weight changes orientation by 1 to 2 degrees. I modified the LCS of the object, of the edge. I have your file but I don't see where the solution is. I even redid the arm with a left orientation but I still have a slight reversal.

[ppemawm]

The good news is that the kinematics seem to be working perfectly. The bodies just need some offset alignment.

I'm tearing my hair out.

Me too. There is a slight misalignment between the sketch that the arm is attached to and item 19 as shown in image7 but I could not find the source:

image7.jpg (46 KiB) Viewed 1926 times

There is also an error in the arm dimension shown in dark green. It should be 7.112 but that should not affect the alignment. I made the same error.

image6.jpg (70.1 KiB) Viewed 1926 times

[Bernard19]

Good morning,
Good news. I'm happy, I just found the source of the lag in the animation. Several errors in the Skt_mvt001. Among other things, there were 4 circular arcs of 21° instead of 2, LCS with shifts. But the main wolf was in the skt_mvt at the level of LCS_17-1 linked to flyweight arm 001. The attachment was made on the small arm instead of the large edge.
I took the opportunity to take the dimensions of the arm.
Now it is necessary to find the relation between a displacement of the flyweights according to the speed of rotation of the shaft.
It was a good exercise. Now the file is good and in addition it is less heavy.

[Bernard19]

Hi,
I retained the solution to group in only one the 02 files of the pistons.
I just realized to my great joy the animation sketch. He works.
Next step the association of the parts to the sketch with the LCS.
I still have to solve the speed variation problem which in the end should manage everything
Cordially

[Bernard19]

Hello,
I still have gaps. I have just assembled my Mvt Rot Trans file in that of the Bati and it is not good.
the 2 files do not have the same orientation. In position and orientation. How do I proceed to move the file Mvt Rot Trans file? I tried with Transformed but as soon as I click on OK, the figure resumes its original position.
The Bati LCS is oriented like the original system. While that of the Mvt Rot Trans, in the middle of the picture, is totally different. Thus we find
Origin |LCS Mvt Rot Trans file
Z -> X
Y -> Z
X -> Y
Cordially

[ppemawm]

How do I proceed to move the file Mvt Rot Trans file?

Use the Assembly4 Edit Placement of Part as shown in the following image8:

Attach to the Parent Assembly LCS_Origin and rotate 90 deg about the X axis and offset as necessary.

image8.jpg (223.42 KiB) Viewed 1521 times

The next step will be to coordinate the axle rotation angle with the sub-assembly Mvt_Rot angle. You can then animate the sub-assembly in the Bati file by running the animator from the sub-assembly file.

[Bernard19]

@ppemawm
Since my last message, I have correctly positioned the pistions file as advised. Thank you so much.
I have just spent 2/3 days trying several things in order to obtain the rotation movement without moving the steering arm on the flyweight file.
So I changed the orientation of the LCS on the lever arm - NOK
On the tree changing the variable initially attached to the angle moved on its LCS, the tree rotates alone - NOK
the Skt attached to the shaft goes to parent > axis rotates + ignition cam but the flyweights or the steering arm - NOK

I can't manage to dissociate these elements, on the one hand certain parts must turn with the shaft and others not. On the other side there is this centrifugal movement for the flyweights.
The movement of the weights works - OK
The spinning movement - Everything spins - NOK. I can't quite put my finger on the solution. Can you give me a clue

[Bernard19]

@ppemawm
Hi,
I have just exploded the flyweight file, on one side I find the flyweights with arm and slider and in the 2nd file there is the steering arm and its connection.
Separately the movements are good but I can't combine the movements. I still have a lot of gaps;
I don't know if this is the right track so I'm testing.
We are waiting for your news
Sincerely

[ppemawm]

the Skt attached to the shaft goes to parent > axis rotates + ignition cam but the flyweights or the steering arm - NOK

You are on the right track trying to separate the two functions.

1. Attach the Part container with the sketch to the Parent Assembly so it will not rotate.
2. Add LCS's to item 19 where the arms 17 are located.
3. Attach the arms to the LCS's you added in #2. This will separate the arms from the sketch and allow them to rotate with the axle.
4. Add another variable and expression to actuate the arms, e.g. arm_rotation=Variables.rotation*21/360 or some other expression you like. I used a conditional. Use a sin function if you want the arms to cycle with each rotation.
5. Use this new variable to rotate the arm 17 LCS's created in #2 about their proper axis.

Hopefully that helps get you back on track. If you still have trouble I will correct your file and return it.

Edits

[Bernard19]

Good morning,
I still haven't managed to make the connection between the rotation and the movement of the flyweights. The parts fly into pieces, make disorderly movements.
The files are okay separately. The motivation is still there but here I must admit that it becomes complex.
Can you help me to move forward?
Cordially