Island size

[fabricator]

I'm building the Dans 17' machine, the coil connections around the island are in a really tight spot, it struc me that it would be easier to keep some more space around these connections by simply making the island a little smaller, the bolt circle of the studs is around five inches, so why does the wiring around the island have to be so tight?

[Dave B]

It doesn't. Experiment, do your own thing, enjoy. There is no "standard" just a good starting point for a design that works.  Dave B.

[bob golding]

i do all my connections to the outside edge. if it doesnt fit make it bigger. no restrictions on size around the outside edge. if fact you might get better cooling.

bob

[fabricator]

Cool, I already started making the island smaller, Dan Lenox's stator short started me thinking of ways to make this less likely to happen.

[windspeed]

maybe not relevant

but when I made my first stator I ran into problems centering it

when I went to drill the outer stator holes the leads out were in the way or to close for comfort

so don't leave it to tight or like me you will have to enlarge the centre after

Windspeed    

[dlenox]

I'd be hesitant to put the connetions around the outside of the stator. This area is used to mount the stator and hole locations are tough to position exactly.

The previous stators used 8" ID and left plenty of room for the coil connections. There have been conversations about flow of air through the inside of the turbine, making the center island  a smaller diameter may inhibit cooling air flow.

My feelings about the stator is to reduce mass as much as easily possible, as that mass retains heat. It still has to be structurally sound and should not move. When you short out the stator to stop the turbine there is an incredible amount of torque that is applied to it, as it has to absorb the energy of stopping the whole blade/rotor assembly.

Dan

[fabricator]

I made it 1.25" inch smaller or 5/8" on each side, so it is 8.75" diameter and there is still plenty of clearance on the stud diameter, it also seems to me that on the next machine I may make the OD larger, another inch or inch and a half would make drilling the mounting holes a non issue.

[Jerry]

My Stators have 8 mounting holes. I bring all 18 wires out to the outside.

In the 14-11 it also has 8 mounting holes, I brought 22 wires out to the outside on that one.

Works great.

                        Jerry

[Flux]

It's far easier to connect on the outside where you have plenty of room.

If the fixing holes are a problem then cast some ears on the stator like Hugh does.

Flux

[bob golding]

should have pointed out that my stators do have ears. it would be dangerous without the ears. the way i positioned my stator was to make a cardboard ring the same outside diameter as the centre of the magnets and fix that to the studs so it is centred, then offer up the stator to the stator mounting arms and, assuming you can see the coils, line them up with the ring. i then clamped the stator and marked the hole positions. if you cant see the coils you should be able to get close enough by eye if you positioned the coils right.

bob

[fabricator]

Excellent idea, I believe I will do that.

[fabricator]

Thanks for the explaination Bob.

[dlenox]

fabricator,

have you made your mold yet?

My mold is 22" OD and 8" ID, so going larger OD / smaller ID is easy if planned up front. Even if your mold is already made you still can take a router to it to modify the outside edge. Preplanning can allow you to put the interconnections pretty much any location that you desire. I even put in a single large 'ear' where the three phosphur bronze bolts bring the 3-phase wires out of the stator.

As Bob stated using 'ears' for the mounting locations works well while still keeping stator mass to a minimum.

Any way you go, just be sure to use plenty of glass matt to help keep a solid structural integrity.

It also does not hurt to pre-fabricate your stator mount and design the mold around it. This way you can be 99% sure of the locations of the mounting points on the final stator.

BTW: have you considered soldering the wires to bronze bolts before you pot the coils?

Dan

[fabricator]

Right now I'm 8.5 ID and 25 OD, and yes, my bronze bolts will have pieces of bronze flat stock soldered to them so they are like a T, making them less likely to spin in the casting, the wires will be soldered to the flat stock.