Stator storie

[SmoggyTurnip]

I built a simple coil winder and mold

and made a stator. It has 21 coils, 18 gauge wire,

196 turns each. Inside hole was 1" by 2" - the

same size as my magnets.

[SmoggyTurnip]

 When I went to connected

all of the coils together I thought it would be easier

to make the connections on the outside of the

coils rather than on the inside because there

was a lot more room there.  I forgot that that is where

the holes were to be drilled to mount the thing to

the stator mounting bracket.  I used baby powder

with my resin so the stator was only semi-transparent.

By putting a bright light behind the stator I could see

most of the wires and I tried rotating the stator mount

bracket around to find a position where I could drill

holes without cutting through a wire.  The first hole

cut 3 wires - the second cut 2 wires - the third cut 3.

Using the light I could see that there was no place

that I could drill a hole without cutting wires. I tried

using a jigsaw to cut along side the cut wires to dig

them out and join them back up again.  This worked

but also cut more wires. After about 8 hours I had

all the wires reconnected, soldered and the holes

patched up with resin.  I decided it would rather

start over than continue with that frustrating process.

I was able to test that stator by mounting it with the

3 holes that I did have - It gave me 168 volts at 198rpm.

I didn't like making the connections from one coil to

The next so I built a new coil winder.

[SmoggyTurnip]

This way I could wind all 7 coils for each phase

From 1 continous piece of wire and not have to

make any solder connections.  I also found counting

196 turns for each coil a bit tedious so I added this

simple turn counter.

[SmoggyTurnip]

 It worked good but I left a bit too much

wire between coils.

[SmoggyTurnip]

When I poured the first stator I used duct tape

for the mold release because that is what I used

when I did my rotors and it worked great.  But

I used epoxy resin on my rotors and it didn't

heat up much.  I used polyester resin on my stator

and the heat it produced caused the duct tape to

wrinkle up a bit so I didn't get a very smooth finish,

It would be ok I think - just didn't look so great.

I wanted to use a different material on my second

try so I tested out this flooring material that I had

lying around.  I poured some resin on a piece of

it, let it harden, and it came off easy and smooth and

I decided I would use it to make my mold.  I still

used the duct tape for the center part of the mold.

[SmoggyTurnip]

I put 21 bolts through the back of the mold, .25" diameter,

one in the center of each coil.  I put a bit of vasilene on each

bolt so they would be easy to remove.  This worked great on

my first stator so I wasn't worried about it at all.  They didn't

leak at all and were easy to remove.  On my first mold I used

a 24 inch diameter circle cut out of MDF for a cover but I was

unhappy with it because some resin got between it and the

center part of the mold and it kept the cover from going all

the way down making the stator thicker than I wanted. So this

time I cut out a ring - it worked much better.

[SmoggyTurnip]

On the other side of the MDF ring I put the flooring

Material so that it wouldn't stick to the material.

I poured the resin at 8:00pm and sat sown and had

a cup of coffee and was happy to finally have the stator

in the mold - what could go wrong now I thought.

I went to check on it at 10:00pm because the first stator

took about 2 hours to harden. Hmmm - this wasn't hard

yet.  Well I thought about the first one and it seemed like

it did all of its hardening in the last 20 minutes - maybe

this one is going to take off any minute now.  While I was

standing around waiting I thought I would put the meter

on the terminals again just to make sure everything was

ok.  First phase OK, second phase OK, Third phase OPEN

CIRCUIT - arrrrg! What happened???  Each phase is one

continous wire so it must just be disconnected from the

stainless steel bolt that is attached to the end of the wire.

Thinking I might only have a half hour or so I remover

the 21 nuts and removed the top of the mold.  I checked

the connection to the bolt and it was OK.  What now??

I took the top piece of fiberglass off and dug around inside

following the wires for that  phase from one coil to the next

and eventually came to a break in the wire.  When I put the

21 bolts through the back of the mold I accedently put a short

one through - when I went to tighten the cover down I noticed

the short bolt - pushed it through the mold and replaced it with

a longer one.  There was a wire pressing against the side

of that bolt and it moved into position to be cut when I

put the new bolt in.  I stripped the wires and connected them

together, bolted the cover back down, and went to bed.

I got up at 6:00 am and went to check on the mold - it didn't

harden at all - "whats wrong with this thing???  Maybe it's

too cold here in the basement, but I did the first mold in the

basement." . I took the mold upstairs and turned the thermostat

up to 75 degrees and left for work.  When I came home it

was hard.  Another hurdle over.  I started taking the mold apart,

-    looking good.

[SmoggyTurnip]

When I took the last part of the mold off this is what I found.

[SmoggyTurnip]

It seems that when I took the cover off to fix the open

circuit one of the washers fell off the cover and went

into the resin. I took my dremil roto tool and carefully

made a small cut around the the edge of the washer and

was able to pull it out .  I drilled the mounting holes and

used my meter to check the phases again and all is OK.

I have not tested this stator yet but I expect it to work -

after all, what could go wrong now?

[electrondady1]

smoggy , those coil look good nice and dense.  i realy like your multi coil jig. i tried to go that way but couldn't get the retaining wire to slip under the inside coils . looks like you found away. i'll give it another try.  i used a 5.5 to one gearbox from an electric lawnmower and an electric drill to motor up my winder. try that next.also a foot swich is good to keep your hands free.

 i poured a stator two weeks ago. turned out great.

last week i tried again but just as i had poured in about half the resin a customer came in wanting a business card. no sweat, caus' the first stator had taken over night to kick.  when i got back to it i discovered the first mixture was already getting stiff. yikes!! mixed the rest and slamed the lid down quick. i didn't realize it was about ten deg. warmer outside.  my 3/8" thick stator is i/2" thick !

 

[SmoggyTurnip]

Actually I did use a sewing machine motor

and geared sown about 16 to 1 with a foot

switch at first, I found it too dificult

to control so I took it off.  Even with

200 turns it doesn't seem to take very long

to wind a coil.  Maybe 3 turns per second.

It all adds up though with 21 coils and 200

turns each thats 4200 turns.  It took about

1. hour to wind each phase.  I took me about
   
2. hours to make all the connections on the
   
   

first stator so I think the ganged coil

winder was worth the effort.

Someone told me that it always takes twice

as long as you think to do something - unless

it looks easy - in that case it takes 3 times

as long. I have to agree.

[oztules]

Grit and determination, thats what I like to see....in it to the bitter end. I have some empathy here with you and your trials and tribulations :-).

4200 turns..... powerful lot of wire there.

Great result, ripping yarn and keep it up...........oztules

[DanB]

I like the idea of winding a whole phase on a long coil winder so you dont have to make connections between the coils....  might try that.

[dinges]

Yes, it's an original idea. Looks very good.

Only problem I have with it is that I usually tie some string around my coils before I take them out of the mould, so they'll stay in shape. I normally use 4 pieces of string per coil. Seems hard/impossible with his method.

But you get rid of the job that I dread most: cleaning all the connections and soldering them together. For single-wire coils it's doable, but for 2-in-hand coils... It's one of the reasons I stay away from 2-in-hand winding, for as long as I can. His method becomes double as attractive for 2 (or even 3?) in hand winding, I think.

Peter.

[RP]

Can you identify the flooring material you used?  That seems like a nice method to get a smooth surface.

[powerbuoy]

Concerning then soldering ... we used to take a blow torch to get rid of the insulation at the ends, then we used a welding tool ...don't know the brand but it had a carbon tip. The ends basically melted together in notime. Zaaaappp ....done, next, zaaapppp done next.

Powerbuoy

[Flux]

For a high voltage machine I would have slipped a piece of sleeving on the interconnections between coils. In the picture with the washer in it I think I see interphase links crossing coils in other phases. This is ok at low volts but it is not good practice for a high voltage winding. It will no doubt be ok but better to play safe.

With your continuous coil set up you would need to thread all the sleeves for one phase on to the wire at the start.

Nice work otherwise.

Flux

[SmoggyTurnip]

I don't know exactly what it is called, around here

everyone calls it "click flooring" because of the

click it makes when you join two pieces together.

It is very popular these days as a cheap alternative

to hardwood in rec rooms etc..  The pieces connect

together verytight so the seam is almost imperceptable.

In the picture with the washer you can see the mark the

seam made but it look alot worse in the picture

because of the lighting.  A light sanding eliminated

the mark completly.

[SmoggyTurnip]

When I built my new stator I decided to

change the dimensions of the coils. I made

the inside dimensions 1.75" by .75". I also

reduced the thickness from .59 inches to

.5 inches so I could get a tighter air gap.

 I made the number of turns 200instead of 196

 - just because its an even number.  My calculations

showed that this would give me about 10% more

voltage (cause I could reduce the air gap)

and 20% less resistance.  This may not

seem like much but a 10% increase in voltage

means a 20% increase in available power and

a 20% decrease in resistance means 25% more

power available (for a given rpm). I wasn't

worried about strength because the stator will

be attached with 21 bolts - that puts 2 bolts

on each side of every coil.

I calculated the resistance of  one phase for

my first stator to be 5.74 ohms and to my

surprise my meter measured it to be 5.7 ohms.

I calculated the resistance for my new stator

to be 4.49 ohms but also to my surprise it

measured 5.6 ohms.  I have the two stators side

by side and using the same meter measure the

resistance of each and I consistently get 5.7

for all phases on the first stator and 5.6 on the

second stator.  I realize that this is not an accurate

way to measure but could there be that much

difference?  I'm still scratching my head over this.

I put my new stator into the alternator last night

and did some testing.  The first thing I did was

spin it up by hand and then short out the terminals

with a knife and watch the sparks.  It actually welded

the knife to the terminals (not a strong weld but impressive).

next I shorted out the phases one at a time and turned

it by hand to feel the cogging just because it's fun.

When I had all three phases shorted out I could still

feel a small amount of cogging.  I didn't feel any

cogging on my first stator when I did this, so I walked

around and scratched my head for a while. It's a small

amount of cogging, just noticeable - maybe its because

I have a more powerful alternator now.

Next test - spin it up using a 5hp motor and check the

voltage.  157 volts at 198 rpm. Hmmm this is less than

my previous stator - more walking around and head

scratching.  Maybe it's my meter connections. I just

switched the meter from volts to ohms and it read 5.6

so that ruled that out.  Well let's check another phase.

Exactly the same thing.  My calculations must have been

wrong but I did them over and over I had confidence in

them.  Well let's check the third phase - 185 volts, now

that's more like it - it's 10% higher than the first stator.

Maybe one of my coils is upside down - but I know I

checked the orientation of all the coils carefully before

I poured the resin. And if one coil was upside down it

would  cancel out just one other coil giving me

5 out 7 coils or 132 volts.  It seemed that there was 6

out of 7 coils active.

I needed a way to test my coil orientation just to

make sure.  I read posts on this boars about people

connecting power supplies to the phases and using

a magnet to test this.  I didn't have any power supply,

I didn't even have a 9 volt battery.  All I could find

was an old AA battery that was in the junk drawer

for at least 2 years.  What the heck - I'll hook it up

and see what happens.  To my surprise I was able to

detect the magnetic field with a neo magnet - it was

weak but I could feel it.  I had 4 extra magnets so

I stacked them up and now it was very easy to detect.

It turned out that all the coils had the proper orientation

but 2 coils were in the wrong place.  Instead of going

ABCABCABC... they went ABCACBABCABC....

I could not believe that I could make a mistake like that.

 I really need to learn some new curse words because I

am getting tired of all the ones I've been using over the

last week.  

Luckily the two coils that needed to be swapped were the

first in the each of the phases so they each had a wire

going to the steel bolts that I used for terminals.  I would

not have to swap these wires I could just swap the wires

that connected to load.  The swap the other wires would

require more brain surgery.  After successfully removing

the first tumor (washer), and having gained some experience

on nerve reconnection on my first stator I felt like I was

now qualified to attempt this operation.  Using a strong halogen

lamp behind the stator for x-rays and a dermal tool for a scalpel

I was able to carefully cut around the wires I needed without

damaging any others.  I was only able to get about 1" of each

wire so they were difficult to strip and I had to add a jumper

to each wire in order to get the required length to reconnect

them, but I did manage to get the job done. I checked the

resistance of each phase and they are all reading 5.6 ohms

again so everything looks OK.  By now it was 1:00 am and

I was tired so I didn't check the magnetic fields with the

battery and magnets but I'm sure I thought of every thing

so what could go wrong now?

[SmoggyTurnip]

Actually it's easy to get the string

around the coils.  If you look close

pictures you can see that I used magnet

wire instead of string.  The wood that

seperates the coils are 1/2 in thick

so i Just bent the wire into a U shape

and set it in the slots.  When one coil

is done just connect the ends.  I only

used 2 but 4 would work just the same.

[SmoggyTurnip]

Last night I mixed up some resin and patched

up the holes that were made during the repair.

Tested the placement and orientation of all

coils using the magnet and battery. All seems

OK.  Was not able to put the stator into the

alternator yet.  Resin hardened OK.

[willib]

wow smoggy !!

you have my sympathy

but i'm glad it is all ok now..

[SmoggyTurnip]

I got my stator problems all resolved.

This is what my alternator looks like now.

I connected 2 25 watt bulbs, a 60 watt bulb,

and a halogen light ( I don't know how many watts)

to the machine and spun it up by hand and this

is what happened:

It's not a very good pic because I was

turning the thing with my right hand and taking

the pic with my left hand.  All the lights came

on to full brightness - it was hard to turn but

I still could have turned it faster but did not

want to risk burning the bulbs out.

My first test was to connect just 3 25 watt bulbs

(110 volts each) and spin it by hand.  I was surprised

to see that after I stopped spinning it by hand that

the momentum of the rotors would keep the lights on

for about 20 more seconds (with the light gradually

getting dimmer of course).

Finally the laws of physics trump the laws of Murphy!

[ghurd]

"Finally the laws of physics trump the laws of Murphy!"

That's not what happened at all!

Murphy has simply been busy with me.

Too busy to spend any time with you.

G-

[SmoggyTurnip]

Please try and keep him busy for a while.

.