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Old 27th March 2013, 07:45 PM   #31
solhaga is offline solhaga  Sweden
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Join Date: Jun 2009
Location: Värsta Götaland
A further comment on #23.
The pleats have to be as parallell as possible.
I´ll simulate that later.
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Old 27th March 2013, 09:46 PM   #32
solhaga is offline solhaga  Sweden
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It doesn´t seem to matter how I simulate the membrane, there will always be fields in the wrong direction.
So it´ll be a traditional motor mount with a traditional membrane orientation.

It´s time to looad the magnets...
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Old 29th March 2013, 08:39 PM   #33
solhaga is offline solhaga  Sweden
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Default Assembling the motor, pt 2.

First I made dummies for the gap, to keep the space open and stopping the magnets from intruding it.
Then mounted the dummies and loaded the first set of magnets.

I will probably load one complete side as the next step. I only got two clamps long enough, so it will have to be it two sessions.
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Old 30th March 2013, 01:32 PM   #34
solhaga is offline solhaga  Sweden
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Default Simulated rods vs solid

In the inverted motor I was able to study what happened with the field with respect to offset or rounded edges of the rods.

What if the iron was solid instead of 3 mm rods with 3 mm space inbetween?

The first three below is the rod simulation and the second three is with solid iron. Note that the layout is just for simulating the field, it is not the real motor.

So the field is actually higher with rods, even if it is not so linear.
Attached Images
File Type: jpg rods vs solid 1.jpg (43.4 KB, 199 views)
File Type: jpg rods vs solid 2.jpg (93.8 KB, 62 views)
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File Type: jpg rods vs solid 4.jpg (52.5 KB, 47 views)
File Type: jpg rods vs solid 5.jpg (82.4 KB, 43 views)
File Type: jpg rods vs solid 6.jpg (55.6 KB, 45 views)
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Old 1st April 2013, 06:46 PM   #35
solhaga is offline solhaga  Sweden
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Default Assembling the motor, pt 3.

So I mounted some more magnets, painted the motors black in order to hide some of the imperfections. Then I made some baffles.

Now I´m waiting for the 3M tape to arrive.
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Old 1st April 2013, 07:17 PM   #36
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It is looking good,and you are making a stereo pair.
How many pleats and what´s the depth of them?
Distance from top to top?

Bernt.
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Old 1st April 2013, 09:02 PM   #37
solhaga is offline solhaga  Sweden
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To be honest, I don´t know. Yet.
It´ll be a lot of experimenting and I must first learn how this motor behaves.
The only thing I really know is that I will be using your excellent technique with the Alu on paper foil together with the 3M 74 Tape.

So folks, I have been waiting a long time to be able to say this:

Pleats, don´t fail me now!
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Old 4th April 2013, 04:35 PM   #38
solhaga is offline solhaga  Sweden
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Default First membrane

I thought of having a simple layout at first.
The gap is 120 mm wide so why not have a 7,5 + 2,5 mm layout with 5 mm Alu strips.
The pleats are 7,5 mm deep and 2,5 mm apart.
That´ll be 120/2,5 = 48 pleats.
Unfolded the membrane is 48 x (7,5 + 2,5) = 480 mm.

So I cut a nail strip into 200 mm long strips to build a pleating tool:

Click the image to open in full size.

Last edited by solhaga; 4th April 2013 at 04:38 PM.
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Old 4th April 2013, 05:53 PM   #39
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I have been calculating a bit.
I use 30 pleats in my latest model,and with 5,5mm stripes i get 3,8 ohm.
I recomend you to use 7,5mm stripes for low impedance and to cover more surface with alufoil.
I have another tool in my mind to get paralel pleats.
Your nailstrip is only 1mm.It might be better with 2,5mm.
Keep up the good work.

Bernt
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Old 4th April 2013, 07:40 PM   #40
solhaga is offline solhaga  Sweden
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This was what I had at home. Just to get started.
But I wonder if the strips really has to be 2,5 mm in order to get 2,5 between the pleats.
I can easily have spacers to make the 2,5 mm with 1 mm strips if needed.
But I guess I´ll soon find out.
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