magnets: to stack or not to stack

[Mary B]

Thanks guys for the additional info. I will take it into account.

I just ran an experiment to see if iron powder filled coils make sense and I think they do.

this test makes use of 2 iron powder bars connected to each magnet. The powder starts after about 2.5mm of print layer height.

I measured without and with powder bars at roughly 16mm distance.
without is around 35 mt and with around 65 mt
incredible !!

now obviously i can't put as much powder in the coils as most space will be wires but I do think it can help if the field will not start to meander around each coil wire.

This did not happen this time because the 2 bars aren't connected so no where to run for the field

I tried using the oscope but I can't figure it out while I am still looking for a manual ;( I have put it in the photo so perhaps one recognizes it and know where I can find a manual .
EDIT: I found a different unit that looks exactly the same that does have a manual. So never mind.

(Attachment Link)

Looks like a clone of this https://jyetech.com/wp-content/uploads/2019/01/dso150-shell-user-manual.pdf

[brandnewb]

Yes Mary, that's the one thank you!

[Jackir]

Using non-iron powder test magnet holders and measuring from 10mm in between the magnet pairs sounds like a reasonable approach. However, to ensure accuracy, consider using a gauss meter to measure the magnetic field strength at specific points.

[brandnewb]

this specific meter also has a gauss setting.

is not gauss just a different expression of the same thing? something like farenheit and celsius?

Can you please elaborate a bit more? I am not sure I see your point ;(

[brandnewb]

I have an update.

And if I have been doing things correctly then I am a happy camper

First I tried calculating a target frequency for the waveform.
Please bear with me it is probably full of blunders and also makes use of a tip speed ratio of 40% I completely made up ;(
Also because the arms have a length of 6m and going +7m like I said before might introduce stability issues I am going to aim for 6m diam.
 

target frequency of waveform
diam of turbine (m)
	circumference of blade tip (c=2pi*r(expressed in m))
6	18.84
wind speed (m/s)	wind speed to tip speed ratio (%)
		blade tip speed (m/s)
5	40	2
time for a full rotation (s)
9.42
number of magnets		pole pairs to calculate frequency
	number of poles (magnets / 4)
192	48	24
target frequency of 2 field reversals for full waveform
pole pairs / time for full rotation
2.54777070063694

So using the oscope I tried to aim for a measurement with the correct frequency. It took a few tries to get the speed correct.
The waveform really shows how to coils are configures. the first and last parts of the wave have less amplitude because only half of the space is filled with coils and the middle which has a stacked coil has a higher amplitude.
When I saw the voltage my spirit got lifted to new heights.as only 1/48th of the disk is being used with this test coil. On the image below we can see the test coil on the right and to the left of it how it would look like if I just kept on installing coils. practically I will have to have single coils every now and them to keep things separable and maintainable.



 

current coil usage of disk
1/48th
current voltage of single phase at target frequency
13.95
projected optimistic voltage with full disk of coils (non stacked coils are not taken into account here)
669.6

Assuming no mistakes were made in either using the oscope and or coming to a target frequency (and I am sure I have ;( )then this is both exciting but also daunting. Because now I have all kinds of new options.

[brandnewb]

I knew it 

Either the oscope is total crap or I am. Probably the latter.

I tried again with this time only a single non stacked coil.



Anyone any ideas? I would be eternally grateful

[Mary B]

I knew it 

Either the oscope is total crap or I am. Probably the latter.

I tried again with this time only a single non stacked coil.

(Attachment Link)

Unless you are actually measuring RPM with a meter accuracy will be so so...

Anyone any ideas? I would be eternally grateful

[brandnewb]

Yeah no Mary. I have an tachometer but the RPM we are talking about will be in the single digits
I really believe that going by frequency (if that frequency was properly determined to begin with) gets one rather close to the mark
I am positive about it

I figured out my mistake in the meantime. In the top left corner of the first image and the reading I was happy with I did actually do a calibration to 0 step.

And then I assumed it would stay calibrated for a while. But as evidenced on the second photo it does not stay calibrated and one should do that step each session on cheap hardware like this.

I can live with that.

The only thing I cannot live with is using a single channel scope on a 3 channel system like a 3 phase alternator. I am looking for something open source but can't find any ones with more than 2 channels. I'll keep looking.

But you have convinced me Mary that multimeters are not the correct tools for things like this. Oscopes it is even though I have barely used one before and do not even know what triggering does and all other related terms.

But i'll get there.

[brandnewb]

EDIT4: TLDR
What I would like to ask about is if we should try and strife for square wave or are sine waves ok?
--------

while I am reading up on magnet to coil ratio's I see a lot of information on the many many variations and that each use case can benefit from a specific set of combinations.

As to the why is probably way above my pay grade so I'll not bother at this stage trying to find out for now.
Other than the mention of asynchronous vs synchronous loads I have gotten here in this thread. That I am still interested to learn about but the resources I find again is way above my head ;( this early in my learning curve.

Anyway. I realise now that I have gotten this nice looking sine wave because the magnet counter pairs are spaced far enough that the field also still crosses to the magnets adjacent to them. EDIT3: After all this is what a dual stator (coil) single rotor (magnet) i.e a coil sandwich depends on. And I know this falls in the exotic category but one of these days I will try and make something useful with it.

The data I have tells me that at a spacing of 20mm there is already a direct path with little to no field crossing over to adjacent magnets. This would result in a more pulse like/square waveform Mary described earlier.
EDIT: (for my specific setup of magnets and configuration) at 30mm there were still fields crossing to adjacent magnets so somewhere in between 30 and 20mm is where the magic happens when not using iron filled coils.

What I would like to ask about is if we should try and strife for that even though we can perfectly reach our target voltage with sine waves (i.e: fields that also cross to adjacent magnets).

I did not specifically test for it yet but will do so next Monday but I am assuming using iron filled coils will also lead to pulse like waveforms.

I am in favour of having the magnet counter parts spaced a bit apart so that the pull between them stay manageable. But if I have to then I am up to the engineering challenges getting them close together will bring

EDIT2: I'd like to add a little anecdote my structural engineer once told me. he said 'you seem to not be inhibited by any knowledge of the field when designing' i.e because you know nothing you try anything.

[brandnewb]

I went ahead and gone and ordered  a 3 channel scope. I want to learn more about this subject.

My question above still stands but I have gone ahead and have an additional question I posted in a new thread. My progress will be posted there until a new fundamental questions arrives and I will create a new thread.

[Mary B]

Yeah no Mary. I have an tachometer but the RPM we are talking about will be in the single digits
I really believe that going by frequency (if that frequency was properly determined to begin with) gets one rather close to the mark
I am positive about it

I figured out my mistake in the meantime. In the top left corner of the first image and the reading I was happy with I did actually do a calibration to 0 step.

And then I assumed it would stay calibrated for a while. But as evidenced on the second photo it does not stay calibrated and one should do that step each session on cheap hardware like this.

I can live with that.

The only thing I cannot live with is using a single channel scope on a 3 channel system like a 3 phase alternator. I am looking for something open source but can't find any ones with more than 2 channels. I'll keep looking.

But you have convinced me Mary that multimeters are not the correct tools for things like this. Oscopes it is even though I have barely used one before and do not even know what triggering does and all other related terms.

But i'll get there.

Read this https://techexplorations.com/guides/tools/oscilloscope/functions/

[brandnewb]

hahaha Thank you Mary. Much appreciated.

I love how you chosen a beginners guide for "busy" people

It is all starting to make sense now this whole oscilloscope thing.

As a thank you I will make good on my earlier statement and also test the horizontal stacked repelling  arrangement. Even though I am not expecting fireworks I at least want to show a sign of gratitude and perhaps sheer madness

[MattM]

hahaha Thank you Mary. Much appreciated.

I love how you chosen a beginners guide for "busy" people

It is all starting to make sense now this whole oscilloscope thing.

As a thank you I will make good on my earlier statement and also test the horizontal stacked repelling  arrangement. Even though I am not expecting fireworks I at least want to show a sign of gratitude and perhaps sheer madness

What is a horizontal stacked repelling  arrangement?

[brandnewb]

hahaha Thank you Mary. Much appreciated.

I love how you chosen a beginners guide for "busy" people

It is all starting to make sense now this whole oscilloscope thing.

As a thank you I will make good on my earlier statement and also test the horizontal stacked repelling  arrangement. Even though I am not expecting fireworks I at least want to show a sign of gratitude and perhaps sheer madness

What is a horizontal stacked repelling  arrangement?

understood my good sir. images say more than a thousand words.



It was brought up here early in the thread. I have always dreaded the idea. But since I am learning so much from you guys I am willing to risk a little dry wall  just to keep things balanced . Is not that a fair deal .

Nah brother. I already think this will lead no where. but but BUT. I might just have to eat my words.



What is your stance on this all?

EDIT: wow such a huge blunder. give me a few minutes I will fix it.
EDIT2: blunder was fixed. image is now correct.

[brandnewb]

this all calls for another explanation.

Please understand that I am able to filter advice. I do so through  multiple sets.

But the ones that keep hanging even though my gut feeling telsl me to not be interested is if it came from someone that I hold in the highest of esteem.

Then I want to make sure the input is felt as treated with the care it deserves.

Look, I'll be blunt. If I could be released from this experiment then I would be saved quite a bit of time. But if one is interested in the results then I will make it so!

[MattM]

Ok, I think your amended picture made a little more sense.  Not sure how that will work out, but you don't owe it to anyone to further their interests at your expense when it will unlikely benefit your project.  You may overthink your design and never get anything done.

[Mary B]

hahaha Thank you Mary. Much appreciated.

I love how you chosen a beginners guide for "busy" people

It is all starting to make sense now this whole oscilloscope thing.

As a thank you I will make good on my earlier statement and also test the horizontal stacked repelling  arrangement. Even though I am not expecting fireworks I at least want to show a sign of gratitude and perhaps sheer madness

What is a horizontal stacked repelling  arrangement?

understood my good sir. images say more than a thousand words.

(Attachment Link)

It was brought up here early in the thread. I have always dreaded the idea. But since I am learning so much from you guys I am willing to risk a little dry wall  just to keep things balanced . Is not that a fair deal .

Nah brother. I already think this will lead no where. but but BUT. I might just have to eat my words.



What is your stance on this all?

EDIT: wow such a huge blunder. give me a few minutes I will fix it.

Tried and proven technique! Several mills have been built this way.

[brandnewb]

understood Mary. I will see if I can squeeze in this test or ignore it for the time being.

Because the material has arrived. I am already building turbine structure MK II. I just can't hold my excitement!!

Also for the bearings needed in MK II I am printing neat umbrellas to keep them dry This time making use of white filament, as to not heat up so quickly by sun radiation, and I will give them a coating to survive harsh conditions.



Don't it look neat ?

EDIT: I would like to explicitly state that I am not advocating for a particular brand of printer. I just can't always avoid having logos in my photos.

Truth be told these printers are a good start but I advise against them anyway!!

EDIT2: I forgot to motivate why I advice against them. Entry level printers like these are easy to setup and get going with but have difficulties printing with more advanced material. Most, if not all, exotic materials need temperatures that these printers can not reach so one is stuck with printing PLA or ABS or a few materials I do not know of yet.

[Bruce S]

brandnewb
No worries about showing the brand name of the 3D printer.
You might get questions from people like me asking the Pros & Cons of the one you have tho  .

This is IF you don't mind the tangent from the subject matter!!

Cheers
Bruce S

[brandnewb]

brandnewb
No worries about showing the brand name of the 3D printer.
You might get questions from people like me asking the Pros & Cons of the one you have tho  .

This is IF you don't mind the tangent from the subject matter!!

Cheers
Bruce S

Bruce my dear brother.. tangent is my middle name! I have been under a constant flux of tangents for a large part of my life anyway

EDIT: so I am more than happy to give any advice I can give. just shoot

[Mary B]

brandnewb
No worries about showing the brand name of the 3D printer.
You might get questions from people like me asking the Pros & Cons of the one you have tho  .

This is IF you don't mind the tangent from the subject matter!!

Cheers
Bruce S

Probably an Ender 3... one of the most popular 3d printers out there... I wen to an Ender 5 for a larger build area/more stable platform

[Bruce S]

brandnewb
No worries about showing the brand name of the 3D printer.
You might get questions from people like me asking the Pros & Cons of the one you have tho  .

This is IF you don't mind the tangent from the subject matter!!

Cheers
Bruce S

Probably an Ender 3... one of the most popular 3d printers out there... I wen to an Ender 5 for a larger build area/more stable platform

I'm vacillating between the Ender & Elegoo Neptune 3 Max. I don't need the highest speed but do like the idea of the extra height I'd go with the Neptune 4 MAX , but just can't seem to press the buy now button.

A lot of the stuff the FD here wants to print in tall, beyond the 300mm range, and they don't mind paying for the filament.

Bruce S

This might turn into a separate thread 

[brandnewb]

this printer is the ender 5 plus. I have chosen it because of its build volume range. rather large prints one can make with this compared to many others.

For entry level printers that can give a descent out of the box experience while boasting this size build volume then look no further.

But I strongly suggest ones does look further

EDIT: or one does not look further yet just take this frame of the ender 5. swap out the board and hot end and what have one and bob is your uncle I will consider doing just that once I am done printing this project.

[brandnewb]

Also. for those interested in 3d printing. Entry level printer normally do not have by default stepper motors that can signal if they have "overstepped"

in practise this means that a bump either from a print artefact or an external fool will more likely result in print misalignment.

a closed loop stepper motor is what i am eyeing on for future builds to address this issue.

Yet ones build plate sensor, if physical, will be more likely to get a more heavy beating when the  printer refuses to skip problem parts and gets back to the exact same spot