6.625" dual rotor update.

[Jerry]

Well a littel more progress on the small alt. Thjere has been some discusion of solid material stators with holes cut for coils. This will be my 4th built that way.

I use the thin fiberglass shower stall wall board. I stack up wafers of this stuff then glue it together and then cut and drill as needed.

The discs for this alt came from an odd motor. This motor had 1 disc with 8 each 1.5" round NEOs 1/8" thick and 1 disc with no magnets.

I baught 8 more 1.5" X 1/8" NEOs and made a jig to set the magnets posision on the disc. I used the fiberglass material for this as well.

I've also wound 6 round coils with a slightly smaller then 1.5" ID. The coils will be imbeded into the holes in the stator for then reson poured over and compreesed between 2 boards. Would waxed papper work as a release ajent?

There will be a 360 degree support around the stator in the form of an 8" cast speaker basket.

Here are the 9 pictures of the so far parts and pieces.

This will be the 4th dual rotor alt I've built this way. I've got 2 more wiating in the wings. Another 8' and a 10" also.

                          JK TAS Jerry

[Jerry]

A few things after the stator has set up I'LL drill a hole through the center for the shaft. Also since these discs have a large 3&3/8" center hole I'll have to machine some form of a shaft to hub to disc adaptor.

Not sure what to expect from the round coils? They have 100 turns of #20 ga. The stator is 5/16" thick so maybe as close as 3/8" magnet to magnet gap?

                          JK TAS Jerry

[Flux]

Jerry

I love your ingenuity but this gives moving coil speaker a whole new meaning.

Do you grade your alternators into woofers and tweeters ( guess this little un is a tweeter)

Flux

[kitno455]

jerry i have a couple sheets of that same material, used to install undercabinet lights in my kitchen. but it is very slick on the textured side- how are you getting that to stick? do you sand it first?

allan

[Jerry]

Hi Allan.

In this alt I've used 4 sheets. I've glude the sheets together with a spray addhisive we use to glue carpet to speaker boxes.

It comes out of the spray can looking like spidder web. you spray each surface seperatly, allow each surface to dry or tack up for a minute or 2 then press them together. This seems to take care of the slick and bumpy surface problem. The back side of the sheeting is kinda dull but smooth.

I glue it and then squeeze it between 2 rounds of 3/4" MDF (1/4" bolts and large washers) over night.

After it sets up its reral strong and light weight. The bumpy surface makes for littel gaps and crevises for the reson to creep into when poured over the coils.

The hole cut for the coils have a ruff a jaged texture for the reson to adhear and grab on to. Seem to make a strong light weight stator. If the wire is small enough, I just use 2 seperate 2 layer wafers.

Put 2 wafers down, drop in the coils, extend the coil wire out then drop the other 2 wafer disc over that. This make a 4 wafer disc with wires comeing out between the center. The bumpy texture makes a bit of a path for the wire to protrude from.

In this alt I'm useing larger wire so I'll drill small hole out the side of the startor and poke the wires through whill droping the coils inplace.

The reson seems to flow and fill in the voids.

                        JK TAS Jerry

[Jerry]

Hi Flux.

I've actuly started a 5.25" speaker basket alt. It has a 4" disc.

The largest basket I've saved for this style alt is an 18".

I have some very nice 10" & 12" baskets. I also have two 12" X 1/4" steel discs I got from Ed. I'm thinking of useing some 1.5" X 1/4" round NEOs on this one.

However this 12" disc alt would requier 15" speaker baskets and I only have one of those in cast. It would be heavy and will requier 2 baskets.

I may just build that one simular to the small yellow alt and, that is simular to Eds kit.

I'm hopeing the 12" discs will give enough room with The 1.5" dia. magnets to allow for wedge shaped coils.

I'm thinking wedge coils are regarded as better then round? Not sure if the round VS wedge coil shape  isue was ever resulved?

I'm not to concerned on this littel 6.625" alt about coil shape and there wasn't enough room for wedge coils on this one anyway.

Its all fun.

                            JK TAS Jerry

[willib]

Jerry , if you havnt cast the stator yet ..

try winding one coil with the center size ,  equal to the distance between the magnets.

and tell me whether or not you get more from the coil..?

[Jerry]

Hi Willib.

The distance between the magnets is 3/8". Seems like a small coil center hole for a magnet that is 1.5" outer diameter?

What do ya think?

                          JK TAS Jerry

[willib]

it did'nt look that small of a gap.

all i can say is i just wound a coil for my 7/8"dia x 1" magnets , the distance between magnets is .450" and that is what i wound the coil,with a .45 hole and it looks great on the scope..

and instead of the 'optimal' 1.75"  od. i made the outer dia 1.52" to save resistance on two less outer loops and ended up with 99 turns of double wound #17  wire with my projected cutin of 107 rpm , right on, it is a real thick coil but with the 1" thick mags it  works for me !

anyway whatever you add to the center of the coil is better than the outside because of less resistance !

my coil dims. are for the double wound,,

http://www.otherpower.com/images/scimages/2965/coil_data_03_31_06.JPG

the nice thing about round coils is that you can predict the output a lot better than any other shape.

[Gary D]

Jerry, if you have 2 coils per phase of #20 wire, that is equal to a phase resistance of #17? It would seem that if you did any modifications to the coils to increase output it would be better to run 2 in hand #20 per coil and egg shape the coils (if there is room on the interior). That would drop resistance per phase down to #14 gauge?Depending on your tests of cutin voltage at the rpm's you want with your existing coil setup, Dan B. has many obsolete single phase machines still posted that way that preformed well(egged shape). In a normal 3 phase setup this "could" cause interactive issues, but you are rectifying each coil separately. Just a thought, it is April fools day after all! A little more crazy today! ;-) Gary D.

[spinner]

jerry

if ya use wax paper, my own experiences indicate that A. make sure the w.p. is not gonna wrinkle up or you'll end up with wavy lookin' pours B. maybe also a thin layer of grease, or whatever, over the side that will meet the resin; just to be sure release is EZ

thanx

spinner

[BT Humble]

Dang, clearly I'm too late to stop you, but I was going to say that this will never work:  you need a 6.627" rotor to work properly with 1.5" disk magnets! ;-)

BTH

[Jerry]

Sorry BTH.

Thats the way this motor came. If I were building the discs from scratch I would have made the discs larger diameter.

Its a littel crowded but I think it might work. I'm not real concerned about the power output on this one. It just looked like a fun littel project.

The last 8" dual rotor I built did more power thren I expected. I thought it would max out at 400 watts. It did 1225 W. That was at 45 mph however. But I didn't think it could reach 400 watts at 50 mph.

This was the alt that I was told voilated Betz law. I may put that one in my wind tunnel with the accurate anamometer to see how far off my truck wind test #s were?

So it will be intresting to see what this small alt will do. I'm also intrested to see how the round coils work?

                          JK TAS Jerry

[BT Humble]

It was a joke, mate! I was just impressed that you went to 3 decimal places in your measurements. ;-)

BTH

[Jerry]

OK BTH, I get it thanks. No need to be sirius all the time LOL.

                      JK TAS Jerry

[BT Humble]

OK BTH, I get it thanks. No need to be sirius all the time LOL.

Oh Pollux - foiled again!  Next time I'll Centauri through your cunning plans and Betelgeuse you in this battle of wits! Aldebaran you! ;-)

BTH

(Sorry!)