Generator Experiment

[maury]

Generator Experiment
Some time back I thought I'd like to build a generator to pair up with one
of my engines. It seems I was never able to get over the hump to get started
on it. Then recently I was poking around on You Tube and ran across a build
of a wind generator. It seemed simple enough and the architecture was
interesting. Unfortunately, the build was heavy on details for making the
obvious parts, but really light on the real engineering of the business parts.
With my background I should be able to fill in here... hahaha..

The architecture is simple: a ring with magnets on each side of a ring of coils.
The flux passes from one magnet through the coil to the opposite pole of the
magnet on the opposite side. The poles of the magnets alternate between
N & S as you progress around the ring. Same on both sides, except the
orientation of the ring is such that N & S are opposite each other.

So I set out to design/build this project. I started by picking the magnets.
This has a big bearing on the size of the overall project.

I looked around the internet for suitable pictures of old timey generators,
picked one, and got busy in Solidworks.

[crueby]

Sounds fascinating - will be watching along!

[maury]

 Crueby, Glad to have you aboard. Don't know what happened to the pict, ... try again.

[Roger B]

Looks a good project      I always like engines to have some work to do 

[kuhncw]

Maury,

I'm looking forward to your generator project and hope to learn more about the electrical design.

Do you know any details about the engine in the photo you posted.  I'm surprised to see it is a 5 cylinder inline.

Chuck

[Dave Otto]

Cool project Maury, looking forward to following along.
I think one of the coolest Generators I have seen is the one that Gordon Williamson built to connect to his beautiful Fairbanks 3 cylinder R engine. If I remember correctly he used the guts of a ceiling fan for the internals, it did a nice job of loading down the engine. Sadly Gordon is no longer with us.

Dave

[steam guy willy]

Hi. Looking good , and in the New Mills building there are quite a few old electric motors from the 1920's   so some good prototypes to measure up and make !!!..

[BillTodd]

Just a thought...

Stepper motors (hybrid stepper)  make good geneators ,  they also have multiple poles so with a squint of the eye the rotor and stator could be made to look scaled 8-)

[maury]

Thanks for tuning in guys.
First off, I was poking around the internet for old generator pics, the one I liked with the 5cyl inline didn't have any text included, so sorry, but I don't have any details on it. There may be a reference to it or a similar engine in the C.H. Wendel books "American Gasoline Engines"

From the posted pics it seems there is some interest in building generators for our models. This project is being designed as a simple to build and inexpensive project. I will be using 3D printing and the machine shop tools I have. So let's get started.

First off, I did a first pass design in Solidworks for the basic parts to get the sizes and look I wanted. I will be 3D printing the housing and stator. The rest of the parts need to be metal.

The End Bells. It turns out, at least on my printer, the outside dimensions of a part are just about right on, but the inside dimensions are a bit under sized. I will be using this feature to treat my printed parts like castings... the holes can be reamed and drilled to correct size. This actually works well and gives a nice internal finish on the holes.
The bell is printed, and machined as shown in the pics. The bearing hole is reamed .001 under size.  A bearing is made and pressed in.

[Admiral_dk]

That looks like at very nice result for that end cover 

I have very recently tried to clean up threads printed in my parts - M4 - and that worked out very well, but I hadn't thought about using a reamer - did you end up with a press fit or glue, to hold the bushing ?

Per

[maury]

Per, I reamed the hole .001 under the OD of the bearing, It pressed in nice and tight.
Thanks for tuning in.
maury

[maury]

Hope everybody had a good time at CF, hope to see some pictures.

SO, the next part of the project will be the magnet ring. I chose .75 x .062
round magnets, you have to be careful with these, if they stick together they
are almost impossible to get apart. During the CAD phase, I designed a holder
 fir the magnets which would hopefully rout the magnetic flux from one
magnet down through the shaft and back up the other side to the second
magnet. I added pockets to keep the magnets from moving, was going
to glue them in, but it was quite unnecessary.

 I chose gray iron to make the magnet rings, and will be using the CNC
to profile and pocket the parts. Two og these parts are required. This
is all mounted on a shaft with two end spacers, and a center spacer. The
end spacers bear against the main bearings to prevent the magnets
 hitting the stator, and the center spacer provides clearance for the
stator to the magnets.

The pictures show progression from the blank stock to the ring with
magnets installed

[maury]

ok, so the next part of the project is to print the stator body, install the coils, and
wire them up. I will be using a 3 phase Y wiring format with a 6 diode bridge to
rectify the output.
Gluing the coils was a bit messy, and the coils were not cooperating very well with
wires trying to go everywhere. I did finally get it assembled and wired up.
A handy feature I put in during the  design was to add a slot around the inside
perimeter of the stator to push the wire connections into.
The stator was then assembled to the stator and installed into the end bells.
I tested the end play on the shaft to gurantee the magnets would not hit the
coils.

[Roger B]

Looking good      I await the results with interest  I have always used commercial small motors as generators (and starters) for my engines.

[Admiral_dk]

I really like it so far - nice ideas

Will you be putting iron cores inside the coils ?

Per

[kuhncw]

Very interesting Maury. 

How did you wind the coils?

Chuck

[maury]

Chuck, good question. Thanks for tuning in.
I made a coil winder setup for my lathe. First I 3D printed a spool that would just
fit into the stator pockets. I designed the geometry so it would give me 300
turns of #28 wire and have the coil just fit snug in the stator. I had no idea how
much output I'd get, just a starting point.
I ordered a counter from a surplus vendor, and went about designing the cam and
trip for the counter. I also printed a bracket to mount the counter in my quick
change tool post.
Then it was simply a matter of winding the wire until the spool was full.

[kuhncw]

Maury,

Thanks.   You just ran low rpm and fed the wire by hand.

Simple and it works.

Chuck

[ddmckee54]

How easy was it to get the coil off the 3D printed form?

[bent]

Following along with interest also.

[maury]

Ok Folks, so here's the scoop. As I mentioned previously, I wired the stator as a 3
Phase generator. I used a 6 diode fill wave bridge to rectify the AC. The output was
disappointing at about 2 1/2 VDC. I could have made a mistake in wiring the stator
but I believe i did it correctly.
There were other inconveniences with the coils. I was able to get them where they
belonged, but it was a hassle and I had to use a lot of glue. So I went back to
Solidworks and made the stator a bit wider to accommodate spools. I designed a
spool to be printed, with with holes, and I redesigned the winder to hold the
spools.
( By the way, to answer a previous question, yes, the coil came off the winder
ok, I added 2 deg of draft to the winder, enabling the coil to be removed. It still
wasted to come apart until I was able to apply the tape.)

So I built the new stator and wired the coils in series. WOW! what an improvement.
Testing the generator at about 300 to about 800 RPM the output ranged from
5 VDC to 10 VDC. with a 150 ohm load.

[Roger B]

As I think Per asked earlier, do you have iron cores in the coils? It is not clear from the pictures.

[maury]

Roger, sorry, guess I missed the question.
No, there are no iron cores in the coils. I suspect that would enhance the output, but the original
information I had from the videos I watched had no cores.
For my purposes, the generator has enough output as is, and I believe it may have enough so I could scale it down a bit. Currently, it's just under 5" in Dia.

At this point I'm going to call the project done, and am working on a steam engine to drive it, and a street lamp accessory. I'd like to thank everyone for their comments and questions, and for tuning on. If anyone wants design
info about this project, just let me know. I'd post the design, but there doesn't seem to be a way to do it on this
site.

maury

[maury]

I can go ahead and share a peek at the engine design I'm working on. It uses some of the features of engines I've worked on
previously: the Dickson steam engine, and the Gothic Beam engine.
The design is not complete at this point. I will be printing 3D patterns to make the castings. Looks like it will be made in
bronze, and I'll be making the bar stock parts from 303 Stainless. For reference o0n size, the flywheels are currently 5" dia.
maury