Dynamo build by castings

[arnoldb]

Very nice castings Manfred; they look great Thm:

You mentioned the "material Ms" - is the "Ms" for Messing ? I'm asking because the castings look like brass or bronze and messing in English is brass.

Looking forward to your progress!

Kind regards, Arnold

 

[manfred albert]

Hello Arnold,

Are you a member on the German site Dampfforum?? Yes and I cooperate with Dampfotto. His 4 cylinder V-steammotor I have in mind to run with the generator.

Manfred

 

[lazylathe]

Hi Manfred,

What username do you use on Dampfforum?
I cannot locate you using your name on this forum.

Andrew

 

[Rustkolector]

Manfred,
I am very impressed with your work on your dynamo project. I am particularly interested in the air coil design you are using. I have reviewed information on both the axial and radial air coil designs, and your adaptation to a model dynamo is quite unique.

I have built two model dynamo projects, but unlike you, I am a bit lazy. I started with solid core motor type stators. My most recent dynamo project required a very slow speed dynamo to give reasonable voltage at 200 to 700 RPM. So far, I am very pleased with its performance. I started out with an 18 pole 200 RPM ceiling fan stator with a solid laminated core. The cogging effect found with most PM motor conversions can be annoying, and can introduce some starting torque requirement, as you have mentioned. In my case, I was able to effectively minimize the cogging effect.

Your dynamo patterns and castings look GREAT. You do very nice work! I look forward to your progress posts.

Jeff

 

[manfred albert]

Hello Jeff,

the fan motor give You a excellent result and to minimice cogging, have a look http://www.otherpower.com/images/scimages/3538/decogging_tutorial_V1.pdf
I due like the coilwindings on this fan motor.
I have in mind , a small generator with a touch of a historical outfit. I believe that it could be done, for a less price, with the fan coil.

Best Regards
Manfred

 

[Rustkolector]

Manfred,
Yes, that is the same website I used for understanding and minimizing my dynamo cogging issues. My fan stator core is 25.4 mm in length. I used the helix method with skewed neodymium bar magnets, and my cogging torque is very low. Neodymium magnets are usually the first choice for building dynamos, but I don't believe neodymium magnets are the best choice for a motor conversion "model" dynamos. Neo magnets are expensive and "very" fragile. They can also be too strong for model dynamo needs. They can create excessive side thrust on sleeve type bearings if the air gap is not held precisely, and their strength can create severe assembly difficulties in a solid stator core. Neodymium magnets would not be a problem with your air coil design dynamo. If you want maximum voltage and power the neodymium magnets are the best choice, but I will probably use less powerful magnets in my next fan motor dynamo.

Jeff

 

[Don1966]

Manfred I have a question. In reviewing the video you posted early in the thread, was this one of yours are did you use it as an example? One of the reasons I am asking, is you had said in the post it was a air core motor, but in watching the video at the end a close up showed metel core in it. This motor was also running on DC with switching transistors.
I will presume that your motor will run on AC instead of DC (with switching transistors). Can you verify this for me? It will make a great AC generator and a unique one at that. Every photo shows your attention to details, this will make a great add on to all of our steam engines. I look forward to your completion.

Regards. Don

 

[manfred albert]

Hello Don,

I`m sorry on that mistake, I just have used this video for a example on air coils. It is difficult fore me to explain, what an air coil is and how it works.
If some one in the comunity can explain that what a air coil is, that would be nice. My English level is to low for that, but growing with every write up.

Best Regards
Manfred

 

[manfred albert]

Hello,

the google maschine is great, I found a link what is a air coil?

http://info.ee.surrey.ac.uk/Workshop/advice/coils/air_coils.html

 

[JorgensenSteam]

From the paper that was posted here the other day concerning generators using air-core coils, the efficiency was surprisingly high.

The paper mentioned the advantage of using air-core coils for windmill and other low-torque applications, where the "cogging" effect found with iron-cores would not be desirable.

Likewise, with a small steam driven model generator, it would be very advantageous to minimize or eliminate the cogging effect, since it would cause a rough running model/system.

Larger rotating devices like motors, and non-rotating devices such as transformers, almost always use iron cores, with the cores maked up of laminated and varnished thin steel layers. Iron cores are built up in layers I believe to minimize eddy currents.

So I have to think that for large electrical devices, an iron core is the way to go if you are going to produce significant amounts of power.

Pat J

 

[manfred albert]

Pat,
I agree on Your points, there is an other aspect high voltage and high power could be dangerous and I don`t need that.

Now the last pattern are really finished and they can move to the foundry. The patter are very strong, so I could use them direct to build the generator or other stuff. The link tells You more about this material.

http://toolingandcomposites.sika.com/en/solutions_products/03/03a001.html

Best Regards
Manfred

 

[Don1966]

Thanks Manfred I did not think the video related to your dynamo. I am familiar with air core coils. Your last photo show how close you are to completation. Will you be offering kit for the Dynamo? In kit I mean casting kits. I am interested in one.

An Pat you are correct about the laminated cores. They are insulated and laminated to reduce eddy currents. For those unfamiliar with eddy currents. It is currents induced into the iron core by magnetic fields surrounding the windings. And I will keep this short and you can google it.

Regards Don

 

[manfred albert]

Hello Don,

I have made an order of 3 gray cast iron kits. One for my son one for me and a spare one.The price I don`t know jet. All the packing shipping will be handled by Maria. The coil body is a 3D print made by shapeways an US company. For this part I can send You the STL file, so You get it printed locally. An other point, I have in my stock tausends neodym magnets grade 45H for a very low price.
But be for we go in to that things let us see how this generator works. The next step is to prepare a test coil, get the rotor finished and run the tests. With that information we will get some idea what the outcome is.

Best Regards
Manfred

 

[lazylathe]

Looks excellent Manfred!!!

Are you going to post all the build photo's of the generator?
I love to see all the set ups and machining steps that everyone uses.

Andrew

PS- thanks for the Dampfforum name, the engine you have posted there is amazing! :bow:

 

[rhitee93]

Looks great Manfred.

I'll be very interested in a casting set if you decide to make them available. The idea about including the STL file for the coil form would be great as I have sources for printing those parts.

Good luck!

 

[Don1966]

Yes Manfred, let us get all the testing done and we can go from there. When you do start to test I would suggest a small load be put on the generator, because of the high impedance of the generator. This way we would get an average voltage reading instead of a static reading before loading. By stepping the load by a decade resistor box and monitoring the voltage till it reaches half voltage we can calculate the impedance of the stator. This would be our max load and we can calculate the current from this impedance, and it makes a simple method of doing it.

Regards Don

 

[manfred albert]

Hi Brian,

check You email, the STL file, a picture and a drawing for the coil body are there.
Be for start printing, wait for the test results from the coil.

Hi Don,
the coil test, we are going to make that together. Now we are getting more and more a international team. That is what I like, let us get all our knoff hoff together.

Best Regards
Manfred

 

[manfred albert]

Hello,

the first coil is ready for a test. In the center I put the magnet for demonstration only.
The wire is 0.5mm and baked together with ethanol. The amount of windings are 30 turns. Few moor turns are possible, I thing 35 - 40 will fit into the coil body center.
The rotor is still in the foundry, so we have to wait.

Best Regards
Manfred

 

[manfred albert]

a week delayed on my castings. Don`t wait, make your on rotor from plastic. I want to know what is the outcoming of this coil. ( 24 magnets only, 32 magnets is the plan )

Inside coil:wire 0.5mm, length 2.9m resistance 0.08706 OHM/m 35 windings
Outside coil the same.

at 1000 rpm and the air gap 0.5mm with out load

inside coil 1V, outside coil 0.5V that will increase about 10% with a iron rotor

So with a total of 12V I`m in a safe voltage range to operate a model engine.

Best Regards
Manfred

 

[manfred albert]

again one week delay with the castings.

2.nd coil winding

wire size 0.355mm and 70 windings, with out load and the plastic rotor with 24 magnets at 1000 rpm. The original rotor is from iron with 36 magnets.

the inside coil 2V and the outside coil 1V, the total with 12 coils 36V AC

The home fan motors are using 0.2mm wire and go up to more than 100V AC in a generator application, there is a wide range to manipulate the output voltage.

Best Regards
Manfred