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Author Topic: CMPT  (Read 19737 times)

z.monkey

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CMPT
« on: May 19, 2010, 11:23:45 AM »
CMPT, Composite Magnetized Planar Transformer...

This is a project I did last winter.  You know, stuck in the garage, looking for some thing to play with...

Howdy All

I am posting this thread of fail because the last two weeks have been another one of those intense learning curves that has resulted in failure.  Granted I did learn a lot about the process of winding planar coils, but I have no good results, so far.

I ordered new Neodymium magnets for my CEET core two weeks ago.  Just after the weekend where I rebuilt the primary (polar red coil) on CEET...
« Last Edit: May 19, 2010, 12:28:01 PM by z.monkey »

z.monkey

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Re: CMPT
« Reply #1 on: May 19, 2010, 11:25:55 AM »

After rebuilding the polar coil I was contemplating the device, and realized the equatorial coil (flat, yellow coil) is mismatched now.  Doh!  gotta build it again.  If you don't build it right the first time, you are destined to do it over, and over until you get it right?  Sound familiar?

I decided to change my strategy concerning the core material and really wanted (but didn't get) a solid NIB (Neodymium Iron Boron) magnet core.  The following Tuesday I ordered the core magnets to build CEET2, well what was supposed to be CEET2.  Here are the core NIB magnets...

z.monkey

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Re: CMPT
« Reply #2 on: May 19, 2010, 11:27:33 AM »
The larger diameter ring in the center is to serve as a mounting point for the equatorial coil keepers.  These keepers are the plastic substrates from CD-ROM disks.  I burn off the media with the microwave oven and use the plastic disc that is left over for this set of keepers.  These keepers contain the windings for the equatorial coil in the equatorial plane of the magnets, refer to Illustration 2-3 in the Alchemical Manual.

Before I could glue the equatorial coil keepers into place I needed to devise a winding jig to hold these keepers in place while we are winding and gluing the equatorial coil.  This is where I started having problems.  The larger diameter magnet in the center of the core has an inside diameter of 1/8 inch.  This is way to small to get a bolt through to use as an axle for the winding jig.  I tried to find a magnet with the same outer diameter, thickness, and a 5/16 inch hole in the center, and could not.  So, I decide to modify the hole size...

z.monkey

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Re: CMPT
« Reply #3 on: May 19, 2010, 11:28:11 AM »
So, not only was this not a good idea, it ruined a drill bit, and in retrospect I could have caused the magnet to catch on fire, or explode.  Don't try to machine NIB Magnets...

So, the remaining NIB magnets, N52s, have a 5/16 inch hole, so I decided to use 5/16 inch hardware for the winding jig axle.  This next shot shows two 5/16 inch fender washers glued together as the mount for the equatorial coil keepers.  Also you can see the stack of NIB magnets, and the 5/16 inch bolt which is used to clamp the entire coil, and act as an axle...

z.monkey

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Re: CMPT
« Reply #4 on: May 19, 2010, 11:30:03 AM »

At this point I am getting excited.  I got the core hole size problem fixed and am starting to assemble the winding jig...

Here we have the finished bottom keeper with a hole drilled through it to pass the start of the windings through.  I have to small nails on the other side to secure the loose wire...

z.monkey

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Re: CMPT
« Reply #5 on: May 19, 2010, 11:30:28 AM »
Then we glue down the top keeper...

z.monkey

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Re: CMPT
« Reply #6 on: May 19, 2010, 11:31:16 AM »
I need to have a small hole to feed through the polar coil wire.  I used a piece of small heat shrink,  shrunk around a piece of wire.  Then drilled an appropriate hole all the way through the keepers, and into the plywood form.  This should maintain a small space so I can later feed through the wire for the polar coil...

z.monkey

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Re: CMPT
« Reply #7 on: May 19, 2010, 11:31:39 AM »
I trim off the remaining stub that is above the keeper and add the other plywood form to the winding jig.  Then I use more fender washers and cut washers to distribute the clamping force better around the winding jig.  I torqued the assembly together very tightly, maybe 25 Ft/Lbs. Tight...

z.monkey

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Re: CMPT
« Reply #8 on: May 19, 2010, 11:32:26 AM »
I want the jig to be as rigid as possible when winding.  If the equatorial coil keepers flex they will bow outward.  The coil will be injected with epoxy as it is being wound.  As the wire accumulates in the jig it will put pressure on the equatorial coil keepers in an outward direction and the plywood forms are there to prevent the plastic equatorial coil keepers from bowing outward...

Here is the winding jig on the drill, clamped to the bench...

z.monkey

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Re: CMPT
« Reply #9 on: May 19, 2010, 11:33:08 AM »
I used a 5 minute epoxy with one of those mixer tubes, and this is where the fail happened.  Haste  makes waste.  I like using 5 minute epoxy for a lot of things, and even in this coil it worked great in a lot of places.  But, winding this equatorial coil took a couple minutes longer, Fail!  It took a solid two  weeks to get to this point, and as soon as I cracked open the jig it was Fail...

z.monkey

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Re: CMPT
« Reply #10 on: May 19, 2010, 11:34:03 AM »
The epoxy started to solidify before I was finished winding the coil.  You can see the gaps in the windings and the irregular, ellipsoid shape...  Fail...

So, up to this point everything happened on Friday 03/05/2010.  Saturday morning I awoke determined to get it right.  I didn't have anymore NIB magnets, but wanted to give it another shot.  So I scrounged up some ceramic ring magnets, just to give the equatorial coil winding another shot.  Of course these didn't fit the jig I built for the NIB magnets, so I have to build another jig, for different size magnets.  I hit the shop hard on Saturday, and built what took two weeks to build before, in about 4 hours...

I enlisted some help for the winding, and gluing process.  My friend applied a thin layer of epoxy to the wire as it was feeding into the coil.  I was controlling the motor speed, and putting tension on the wire to make sure we got it all the way in there.  We were still using a 5 minute epoxy,  and even though this coil is a lot more symmetrical, it still has the problems where the epoxy started to harden before all the wire was in place...

So, here we can see the two botched coils I built this weekend...

z.monkey

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Re: CMPT
« Reply #11 on: May 19, 2010, 11:34:33 AM »
Then here is the entire collection of Fail...

z.monkey

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Re: CMPT
« Reply #12 on: May 19, 2010, 11:34:57 AM »
No, I don't really consider this to be failure...

Failure is an impostor.  We learn more by failing than we do by not trying...

So anyway, I am starting to get the process worked out.  I need to use epoxy with a longer set time, so I can get all the windings in there before the epoxy goes solid.  Also I have built two winding jigs that I can use for 1.15 inch diameter ceramic magnets, and 1.0 inch diameter NIB magnets.  Not having to remake the winding jigs makes subsequent coils easier.  I solved the magnetic core inside diameter problem by using steel washers instead of a NIB magnet.  Then also worked out the wire handling holes...

Actually its been three weeks since I jumped back into this project.  So, maybe, within a month I have a usable equatorial coil, and I be able to go back to testing...

z.monkey

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Re: CMPT
« Reply #13 on: May 19, 2010, 11:37:24 AM »
OK, here is where we pickup again, two weeks later.  Got some more magnets and new ideas.  So back to the garage...

CEET2 Redo...

Howdy All,

OK, here we are again winding an equatorial coil.  This time I have 50 minute epoxy which will be more flexible when we are winding the coil.  The trade-off is that it is not a clear epoxy.  There is a black component and a white component and when mixed is a dull gray color.  So, anyway we are going to assemble the pieces in the winding jig as before...

z.monkey

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Re: CMPT
« Reply #14 on: May 19, 2010, 11:38:06 AM »
The other epoxy had a mixing tube and this one does not.  So I decided to mix the epoxy in a glue syringe so that I could inject the epoxy into the small space between the equatorial coil keepers...