Model generator build from scratch

[Steamchick]

You are correct: But the magnetic flux in the iron "focused" generator is 10 ~100 times bigger than the flux in air. It's a thing called Magnetic permeability. A bit like carbon and clay in a pencil lead can conduct electricity ...,. but copper, aluminium and silver just do it so much better that people use those materials instead. Are the casings aluminium? That is so much better than air - but a long way off the "magnetic soft iron" used commercially.
Look up the numbers for permeability of materials on Wikipedia.
I'll catch-up with you tomorrow.
How much does a set of castings and drawing retail for? Methinks this may be my next project. (maybe with some mods....? I have some old motors and stuff that could donate some "magnetic iron").

K2

 

[darwenguy]

You are correct: But the magnetic flux in the iron "focused" generator is 10 ~100 times bigger than the flux in air. It's a thing called Magnetic permeability. A bit like carbon and clay in a pencil lead can conduct electricity ...,. but copper, aluminium and silver just do it so much better that people use those materials instead. Are the casings aluminium? That is so much better than air - but a long way off the "magnetic soft iron" used commercially.
Look up the numbers for permeability of materials on Wikipedia.
I'll catch-up with you tomorrow.
How much does a set of castings and drawing retail for? Methinks this may be my next project. (maybe with some mods....? I have some old motors and stuff that could donate some "magnetic iron").

K2

You will just have to wait and see then wont you, your untrue statments just
add confusion to the thread. The castings are basicaly just cosmetic and would still work if made from plastic. Iron will increase performance up to 25 percent thats all check for yourself.
Il have have this finished in a couple days and it will work as i intended it to.

 

[Steamchick]

Hi Luke, Maybe you can post your calculations? I am without all the dimensions to do any myself.
I'm trying to resolve what I remember from Maxwell 40 years ago with what you are achieving. But I'll admit I haven't done the calculations since about 40 years ago, so may have got things mixed-up somewhere. I do remember working with various motorcycle alternators, and the difference between a 0.004in. And 0.006in air gap at the poles significantly reduced the output. Equally, reducing the air gap from 0.004in. To 0.002in clearance gave 30% to 50% more current. My instrumentation wasn't very accurate, but bulb sizes and flattening batteries gave me a good comparitor.
I like what you are doing, but I just don't understand the whys and wherefores.
Cheers,
K2

 

[darwenguy]

Hi Luke, Maybe you can post your calculations? I am without all the dimensions to do any myself.
I'm trying to resolve what I remember from Maxwell 40 years ago with what you are achieving. But I'll admit I haven't done the calculations since about 40 years ago, so may have got things mixed-up somewhere. I do remember working with various motorcycle alternators, and the difference between a 0.004in. And 0.006in air gap at the poles significantly reduced the output. Equally, reducing the air gap from 0.004in. To 0.002in clearance gave 30% to 50% more current. My instrumentation wasn't very accurate, but bulb sizes and flattening batteries gave me a good comparitor.
I like what you are doing, but I just don't understand the whys and wherefores.
Cheers,
K2

You seam to be looking for problems that dont exist.
Ive recorded all my method and finding from the start of this thread what more do you need.
Did you even read the link to that thread of the beutifull model manfred designd and made himself? It works on the exact same method, Or did you just tell him he should use an old motorbike alternator instead!

 

[Steamchick]

Sorry, I don't mean to upset you, but I picked up odd threads at different times. When I get time I'll study it all.
K2

 

[mu38&Bg#]

Nobody questions whether this generates some power.

A few are trying to convey the importance of proper design.....
I said I wouldn't comment when it became clear after my initial response that the electromagnetic design of this generator was irrelevant. If the goal was to make a few watts regardless of efficiency, certainly that could be achieved. Fundamental electromagnetic design was well understood a century ago.

It doesn't "need" iron, but you have to understand what you're giving up without it. There is a tremendous loss in power density, they use far more magnet and copper than a standard design. Those DIY generators do "work", but are poor designs overall. When there is no constraint on size or efficiency, this can be acceptable. There are "ironless" designs, but even those use iron.

I understand giving up efficiency and the effort of a detailed design in exchange for something that "works" and looks the part is the goal here. And that is fine. No need to get defensive about it, but understand that people are trying to help with a proper design.

You will find the torque required to drive the generator with the aluminum housing without stator back iron will be much greater than the plastic print.

 

[darwenguy]

Nobody questions whether this generates some power.

A few are trying to convey the importance of proper design.....
I said I wouldn't comment when it became clear after my initial response that the electromagnetic design of this generator was irrelevant. If the goal was to make a few watts regardless of efficiency, certainly that could be achieved. Fundamental electromagnetic design was well understood a century ago.

It doesn't "need" iron, but you have to understand what you're giving up without it. There is a tremendous loss in power density, they use far more magnet and copper than a standard design. Those DIY generators do "work", but are poor designs overall. When there is no constraint on size or efficiency, this can be acceptable. There are "ironless" designs, but even those use iron.

I understand giving up efficiency and the effort of a detailed design in exchange for something that "works" and looks the part is the goal here. And that is fine. No need to get defensive about it, but understand that people are trying to help with a proper design.

You will find the torque required to drive the generator with the aluminum housing without stator back iron will be much greater than.


Glad you understand my design now can i please get on with it.
I wont be using iron sorry this offends you sooo much. But this convosation is sounding like a broken record now have a nice day my friend.

 

[TonySteamHobby]

The castings look great! Any chance you have video of the process?
Great project, keep it up.

 

[darwenguy]

Thanks tony, do you mean the casting process, i dont, i learnt most of what i know from watching 'myford boys' videos hes a great teacher!
Undate so far got to excited and already machined all the parts, forgot to take pics. I may record a detailed build log of this when the design is settled.

 

[djswain1]

Hi all, so i got some decent castings all fettled and ready to machine in the morning now, actually already started on the rotor. I should have the first model finished by next week.
Il do another test when its finished now, il have to get some 12v car bulbs to show you as i only have 12v leds and it blows them in seconds as soon as it goes over 500rpm.
View attachment 125192
View attachment 125193
View attachment 125194

Those castings look really good. Liking the mix of technologies as well, CAD 3D printed parts to make an alternator for a steam engine.

 

[darwenguy]

Hi all, im very close to finishing this mk1 model now. Finished up all the machining and painted all the castings today, just needs assembling tomorrow
The build process goes like this...
A 3d printed plastic ring holds all the coils in position, i only had red plastic for the printer so this one has been painted black for cosmetics.

And how it fits in the housing. You can see the size here! The pics dont realy show you the scale of this model. Although i do have big hands ha.

The coils are all wound the same, the start lead of each coil is marked with a loop....

The coils are then super glued into the ring. They must be alternating in the direction of winding! This is done by positioning them with the two loops next to each other than the next join is two straght wires then repeat all the way around(two loops, two straght)

The ends are then trimed and the wire coating is burnt off and sanded to bare copper. The pairs of wires are twisted together and soldered. Then small sections of shrink wrap is used to insulate the conections. And joins are tucked away neatly between the coils.

And the finished stator ready for fitting..

Also had to glue the 25x10x3mm neodymium magnets into the rotor.

And thats about it all done ready to assemble tomorrow.
Heres the parts painted and drying

 

[darwenguy]

Those castings look really good. Liking the mix of technologies as well, CAD 3D printed parts to make an alternator for a steam engine.

Thanks, the cad and 3d printing have been a steep learning curve and ive just about got the hang of it after about 4 years haha.

 

[mnay]

Great job, the castings look perfect.
Mike

 

[kuhncw]

Very nice work. I like the vintage look.

Chuck

 

[darwenguy]

Hello all, ive got this model finished now and il be honest im pretty pleased with myself.
It performs way above expectations and i hope you will agree it aint too ugly to look at. so ive more than met my goles on this first setup
Heres a few pics of the assembly and the finished model.
the stator ring is fitted in the housing just a nice push fit holds it in place.

Fitted m3 studs to the base..

The little bridge rectifier is fitted into the base, a hole is drilled to fit the red led of the rectifier so it can be seen when running. Also fitted the two DC thumb terminals though they could be made smaller maybe.

And the finished model as it will look, the oil cups are just cosmetic but more shiny is always more better

And next to my other little generator..

Il set it up with some lights to display the output and post pics and video soon
Best regards.
Luke.

 

[awake]

Very nicely done, and great job with the pictures to document it. I'm eager to see a video!

 

[darwenguy]

Here is my quick and dirty setup as i imagined it would be setup before i started.
It has more than enougth power to light my little lamps. My other model generator only lights one of these at normal speeds. Il find a bigger load to test it more. The LEDs i have here just start blowing at around 600rpm they are operate on 5v-12v dc.

And it running with the shop lights off.

Video coming in a min.
..

 

[darwenguy]

Video here, the lathe sounds even more clunky in the audio haha. The speed is a little awkward to adjust on the lathe but gives a rougth measure of rpm.
I coild easily get more power from this model if i use more wire or even thicker wire an more of it, there is a lot of space to make bigger coils. But i just dont need that much electricity starts biting!

 

[skyline1]

Smashing job Luke it really looks the part and works well too

I agree about the terminal posts a couple of little brass studs with some tiny wingnuts would look more period.

If you want to go the whole hog, braided fiberglass Hi temp wire painted black looks just like old cotton covered wire which would likely be used on something like this.

Best Regards Mark

 

[darwenguy]

Cheers Mark.
Yes the terminals are a bit ugly they need changing. They were just what i had about, brass screws fiber washers and wing nuts sound like the plan.
Also did try getting some braided wire but its hard to find thin stuff. I did get some of the high temp stuff at 2mm but this turned out to be the actual copper wire size and the outer is nearer 4mm so way to chunky. Any thoughts on a supplyer?
Also the ugly screws nailing it to the wood was an after thought, so going to add some nicer looking lugs onto the outside of the base casting. Il prob do a full cast base eventually to display it with an engine i havent even made yet haha.
Best regards.
Luke.