Build diary

Anything about construction that doesn't fit into any of the above

Build diary

Postby esawyja on Thu Oct 30, 2008 4:12 pm

I'm hoping to post photos of my build based on a Hugh Piggott design.
Day 1 - The coil winder
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Flame cut disks - 300mm OD, 65mm ID x 8 mm - Got them cut in JHB by Zondiac Steel - R141-00 per disk
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Re: Build dairy

Postby esawyja on Thu Oct 30, 2008 4:17 pm

Day 1 - Continue
Flame cut disks
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Disk with magnet placing template from 6mm plywood
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Re: Build dairy

Postby esawyja on Thu Oct 30, 2008 4:24 pm

Day 1 - Continue

The mould for the stator, 19mm pine base, 13mm plywood mould and 19 mm pine lid
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The mould and the lid and my toe... sorry
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Thats all for day 1, will continue uploading photos as I get along ... waiting for the wire, hopefully I get it before the weekend, so I can wind the coils and cast the stator.. come on SAPO.. I need the wire..
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Re: Build diary

Postby esawyja on Mon Nov 03, 2008 6:43 am

Day 2 - Modification to coil winder to hold the wire reel
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10 coils wound - 70 windings of 1.6mm wire each - all of them coming in at 220 g
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All 10 coils - ready for connection
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Last edited by esawyja on Mon Nov 03, 2008 6:57 am, edited 1 time in total.
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Re: Build diary

Postby esawyja on Mon Nov 03, 2008 6:50 am

Day 2 - Continue
Ring connection done - Connected all the start tails together in a ring
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All the other connections made - All the end tails connected to wires
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Fibreglass cloth at the bottom and the 1st layer of fibreglass resin
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I'm using car polish as a release agent... hopefully this is going to work out....
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Re: Build diary

Postby esawyja on Mon Nov 03, 2008 6:56 am

Day 2 - Continue

Mixing the filler resin - 400g fibreglass resin - 400g talcum powder
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Filled to the top
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Its gonna be one sweet smelling stator...
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I have closed the mould, so hopefully I can get the casting out on Monday, will upload photos of the casting.... to be continued...
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Re: Build diary

Postby esawyja on Tue Nov 04, 2008 7:10 am

Day 3 - Disaster
This did not work out, I do not think I used enough hardener, the fiberglass is still sticky and there is a problem with the mould, the lid did not close properly. What I do not understand is that in the instructions, the spacer in the coil winder is 13 mm, the mould is also suppose to be 13 mm, surly you should have at least a millimeter gap of some sort, to allow for the thickness of the fiberglass on either side of the stator face, etc...? The coils were higher than the edge of the mould, so even though I screwed the lid down with plenty of screws, it did not compress down hard enough, it actually pulled to the one side....
I added some more hardener and fiberglass and screwed the lid down again, trying to equalize the thickness of the stator... I'll see tonight if it was a success..
Lessons learned..
1) Use the amount of hardener specified on the product, not the amount specified in the instructions..
2) If something does not make sense, follow what you think should be correct, I should have increase the mould thickness with at least 1mm...
Hopefully it will come out ok.. If not, I'll have to order more wire and redo the coils and mould... Expensive mistake!!
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Re: Build diary

Postby windgat on Tue Nov 04, 2008 9:45 am

Ow!! I feel your pain... Maybe it should be some comfort that it is very rare that our first attempt at anything is a 100% success.

Resin is not easy to work with. There are also different formula's, so as you say, use the instructions on the product. The amounts can be very very critical - so measure carefully. When you say resin, is that polyester or epoxy resin? I wonder if given more time it would set? Maybe if you can heat it, e.g. by leaving in the sun.

I was worried about using wood as a mold. It needs to be completely flat, and perhaps pine is not the best. There again you used thick plans, so maybe it is ok.

What I can't figure out about the design you are following, is why does the mold need a top? Why not just pour in enough resin to hold the coils firmly, and never mind the top is not flat?

And a suggestion (which I am not sure I would follow myself!): Next round, make one wire coil. The copper is expensive, baby powder and resin is cheap. Then cut wooden (or something) dummies for the other coils, and do a test casting. If the mold works well and the resin sets nicely, then go for a full set of coils. That dummy stator may also be useful as a test component when assembling the generator - you would not have to worry about damaging or cracking the one with the coils in it.

Thanks for posting your diary here, and keep going!
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Re: Build diary

Postby esawyja on Tue Nov 04, 2008 11:05 am

windgat wrote:What I can't figure out about the design you are following, is why does the mold need a top? Why not just pour in enough resin to hold the coils firmly, and never mind the top is not flat?


I think what he doing is trying to keep the faces of the stator as flat as possible, as his design has the rotors on either side, so I suppose if the one side is not as flat as possible, the airgap need to be bigger or maybe difficult to adjust... Not to sure what kind of resin this is.. I will check and let you know
:shock: Back to the drawing board I suppose... :cry:
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Re: Build diary

Postby esawyja on Wed Nov 05, 2008 7:48 am

Day 4 - I removed the casting out of the mold, it does not seem to be tooooo bad.. It is still a bit sticky, but I'm going to try and leave it in the sun for a couple of days, the face is nice and flat on the one side, but on the other side, the face is flat on top of the coils, with some holes, but I'm going to try and fix that up by using some resin and filling the holes..
windgat wrote:When you say resin, is that polyester or epoxy resin? I wonder if given more time it would set? Maybe if you can heat it, e.g. by leaving in the sun.

The resin just says Poly-Metal fibreglass resin on the tin...
Some photos of the stator out of the mold
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Attachments
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Re: Build diary

Postby windgat on Wed Nov 05, 2008 9:51 am

Looks like its rescued - well done. :D

as his design has the rotors on either side, so I suppose if the one side is not as flat as possible, the airgap need to be bigger or maybe difficult to adjust

I don't think its important that the resin is flat. What really matters is that the tops of all the coils are flat. As long as the coils are firmly held, I wouldn't bother with trying to fill any little holes. (I also have rotors on both sides of the stator).

Oh, and a warning: make sure the stator is completely flat as it hardens. Perhaps best to even leave it in the mold. If it warps as it sets, then you will have to make the airgap bigger to compensate for that.

'Poly-Metal'... not sure what that is, but it sounds like Polyester resin. Wonder what 'Metal' means?? I think suppliers often put their own names on these products.

I look forward to the next installment!
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Re: Build diary

Postby esawyja on Mon Nov 10, 2008 6:47 am

Day 5 - Did not do a whole lot, got the wheel hub off a Toyota Corolla 1.3, cleaned it up and checked the bearings
Drilling the mounting holes
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The 4 jacking screws drilled and tapped
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Checking the mold and template fit, I placed one magnet on the steel disk, nearly lost a finger, man these magnets are STRONG :shock:
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Re: Build diary

Postby esawyja on Mon Nov 10, 2008 6:51 am

Day 5 continue - 1st disk with the magnet template
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1st disk - Magnets superglued in place
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1st disk in mold
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Re: Build diary

Postby esawyja on Mon Nov 10, 2008 6:57 am

Day 5 continue - 1st disk in place with island in the middle to keep the resin from the mounting holes, 100g of resing in mould already, 300g resin and 250g talcum power next
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Fibreglass mat ready to be placed on top of the magnets
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Ready for the lid to be closed
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Re: Build diary

Postby esawyja on Mon Nov 10, 2008 7:02 am

Day 5 continue - Lid (3mm hardboard) placed on top, with a lot of metal on top to squeeze it down, you can see the resin seeping out the top and sides of the mold, sure hope I'll be able to get it out of the mold....
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The Toyota Corolla 1.3 wheel hub that I'll be using
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And thats all for now.... Still to do, the 2nd disk and the bearing mount...
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Re: Build diary

Postby windgat on Mon Nov 10, 2008 6:24 pm

Looking good! Do you think its necessary to super glue the magnets down? Might they stay in place due to the magnetic force alone?

I wonder what function the glass mat on top of the magnets serves? seems to add to the minimum 'air' gap (i.e. gap between the magnets and the coils).
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Re: Build diary

Postby esawyja on Tue Nov 11, 2008 3:55 pm

windgat wrote:Looking good! Do you think its necessary to super glue the magnets down? Might they stay in place due to the magnetic force alone?


I was a bit scared that when I remove the magnet template, that all the magnets might go whooosh and all stick together with my hand in the middle.... :roll: As for the mat on top, who knows.... suppose just another safety feature to keep the magnets from flying off into space or something....
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Re: Build diary

Postby esawyja on Wed Nov 12, 2008 1:34 pm

Day 6 - Took the rotor out the mold, looks ok
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Re: Build diary

Postby windgat on Wed Nov 12, 2008 2:28 pm

Ok! Ummm.... is it my eyes or is that hole in the resin not quite in the centre? If not, the rotor is not going to be balanced, and may vibrate when spinning at speed...
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Re: Build diary

Postby esawyja on Thu Nov 13, 2008 8:42 am

windgat wrote:Ok! Ummm.... is it my eyes or is that hole in the resin not quite in the centre? If not, the rotor is not going to be balanced, and may vibrate when spinning at speed...


Jeez I never saw that, I sure hope it is in the centre! It could be the angle that I took the photo, also, I have not cleaned the extra resin off, maybe (hopefully) it is that!!
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Re: Build diary

Postby esawyja on Mon Nov 17, 2008 6:26 am

Day 7 - Made the bracket
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Placed the magnets for the back rotor - ready for casting
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Re: Build diary

Postby esawyja on Mon Nov 17, 2008 6:30 am

Day 7 - continue - 400g resin and 250g talcum powder
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Fibreglass mat on top of magnets
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Ready to close the lid
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Re: Build diary

Postby esawyja on Mon Nov 17, 2008 6:48 am

Day 7 - continue - Lid closed
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Checking the stator fit on the bracket
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Bracket without stator
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And thats all for now....
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Re: Build diary

Postby esawyja on Tue Nov 18, 2008 6:28 am

Day 8 - Removed the rotor from the mold, getting better at this, this rotor came out much better than the other one
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Re: Build diary

Postby windgat on Tue Nov 18, 2008 8:49 am

Looks good! And the hole looks like its centred. Was the other one off centre or was that an optical illusion? Do you plan to make a jig to check the balance of the rotors?
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