Can someone confirm this in FEMM?

[robbie47]

Robbie,
I tested your modified file and the changes you made shifted the optimal position of the lower small magnet.
It now seems the best starting point is at a distance of .025" from the center line of the upper small magnet.
After moving the large magnet .55 to the right, the small lower magnet would then need to have the polarity reversed then moved over -.175" so the opposite side is .025" from the center line of the upper small magnet to reverse the process.

It should not be necessary to simulate the reversal because in theory it should be the same as the first cycle only opposite.

You could use the fade in and out idea, to simulate the lower magnet moving in and out of the screen and this would show the best case condition of the setup. Moving the lower small magnet up into position and then down at the end of the cycle would show the worst case condition. Sliding in and out of the screen should fall somewhere in between these conditions.

I repeat the steps that I now understand from you last indications, starting with the modified file I posted earlier:
First shift the bottom small magnet 0.01" to the right (its new preferred starting position), then:
1) Move the long magnet 0.55 inch to the right
2) Reverse the polarity of the bottom magnet (180 degrees)
3) Shift the bottom small magnet 0.175" to the left
4a) Shift the bottom magnet down as a fade out, or
4b) decrease the magnet strength of the bottom small magnet in steps to zero strength.

[lumen]

Robbie,
That is correct, except you can avoid all the shifting at the end.
1: move bottom magnet up from bottom of screen (or fade in), into the new position (.025" off top magnet center line)
2: move long magnet .55" to right
3: move bottom magnet down to bottom of screen (or fade out)

These steps should cover the entire setup since the movement back would just be the same thing from the other end of the setup.

[robbie47]

Robbie,
That is correct, except you can avoid all the shifting at the end.
1: move bottom magnet up from bottom of screen (or fade in), into the new position (.025" off top magnet center line)
2: move long magnet .55" to right
3: move bottom magnet down to bottom of screen (or fade out)

These steps should cover the entire setup since the movement back would just be the same thing from the other end of the setup.

Lumen,

Some first results attached.
The pdf contains 3 pages:
page 1: X and Y forces of top small magnet
page 2: X and Y forces of middle long magnet
page 3: X and Y forces of bottom small magnet
Each page contains 3 steps:
step 1: move middle long magnet 0.55" to the right
step 2: move bottom small magnet 0.175" to left
step 3: move bottom small magnet down 3"

Also attached the Femm file (zipped) where the bottom magnet has moved 0.1" to the right as you indicated as new preferred location
Also attached the lua script file (zipped). If you use this file it will modify the femm file, so you should backup the original femm file first before running the lua script. The lua script moves the magnets stepwise, each step is analyzed and all forces are written to text files.

The output contains 3 text files (zipped) that you can import in e.g. MS Excel
The file names should be clear enough.
Each file contains two columns; the left one represents force results of the x-component; the right column represents force results of the y-component

[robbie47]

Lumen,
Our posts just crossed each other.
Let me know if the format is something you expected.

Then I will modify the script so the sequence will be like you indicated latest:
1: move bottom magnet up from bottom of screen (or fade in), into the new position (.025" off top magnet center line)
2: move long magnet .55" to right
3: move bottom magnet down to bottom of screen (or fade out)

Where does the polarity alteration of the bottom magnet fit in?

[lumen]

Robbie,
The polarity change of the bottom magnet is after the sequences 1,2,3 and that would be as follows.
4: Shift lower small magnet -.175"
5: Change polarity of lower small magnet
6: Move lower small magnet back up (or fade in). This is same as step #1 but now on the other side of the center line of the top small magnet by .025" and most the large magnet is now on the right side.

These steps are probably not needed because they are only to operate the mirror process and should show the same results as the previous steps but in the opposite directions.
I want to take a look at the results you posted and see if it's what I was getting.