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Author Topic: Dia. Mag. Alternator  (Read 190182 times)

Lakes

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Re: Dia. Mag. Alternator
« Reply #210 on: June 10, 2011, 11:24:32 AM »
You could do with a couple of stepper motors attached to that mini-mill.. ;)

z.monkey

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Re: Dia. Mag. Alternator
« Reply #211 on: June 10, 2011, 12:30:48 PM »
You could do with a couple of stepper motors attached to that mini-mill.. ;)
Yups...
3 axis would be nice...

z.monkey

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Re: Dia. Mag. Alternator
« Reply #212 on: June 16, 2011, 01:16:34 PM »
Finally got a chance to finish cutting DiaMag7-2.  The cutting went faster because I had less issues with the milling table.  Also getting more experience with the machine in general.  I am moving the mill 60 mills between cuts, and then doing a side mill finish in the slots.  The Y Axis on the table wasn't quite square, so the slots are a little slanted.  On the next set of plates I'll try a finish the slots before I break the ends to make better, uh, smoother slots.  The plywood sacrificial block was kind of a problem.  It started disintegrating under the plates in process.  This made clamping a little more difficult.  I may use a piece of poly for the next build.

Now need to cleanup the plates, cut some 1/4 inch aluminum tubes for the standoffs, and assemble the frame subassembly.  I am going to wind 8 individual 26 AWG coils on this one.  Each will have its own full wave rectifier, and then the outputs will combine in parallel for the test...

z.monkey

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Re: Dia. Mag. Alternator
« Reply #213 on: June 17, 2011, 01:41:44 PM »
Got the standoffs built.  Next is the vinyl inserts, and winding...

z.monkey

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Re: Dia. Mag. Alternator
« Reply #214 on: June 17, 2011, 08:40:51 PM »
What do you do at work on Friday afternoon, when you got nuthin' to do?

Draw alternator plates, of course.  This is NeoMag8.  This one is going to take four plates.  Two plates make the wire form, and the other two plates are for mounting the bearings which hold the shaft and the rotor.  The wire form plates are 4 inches in diameter.  They will use the same standoff scheme as the DiaMag7, but this time the winding slots are open on the inside.  So there is a big opening (2 inches) in the middle of the wire form plates.  This is clearance that is needed to wind the coils.  Then the rotor will fill up that space, and we will use the external bearing plates to hold the rotor in place.

Now I need to liberate the four plates from the rest of this piece of stock.  This plate was clearance priced.  Apparently it was cut for a customer and then not purchased.  So the retailer marked it down.  It is a little larger than what I need, but I'll have some decent sized scraps left over for something else.

Back to shredding metal!

z.monkey

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Re: Dia. Mag. Alternator
« Reply #215 on: June 17, 2011, 10:30:43 PM »
This new plate is thicker, 0.125 inches, harder to cut with teh hacksaw...
I'll probably have the outlines on all four plates cut in a few hours...

z.monkey

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Re: Dia. Mag. Alternator
« Reply #216 on: June 29, 2011, 11:55:41 AM »
Looking forward to the Holiday to get some metal shop time...

I used a left over piece of 1/2"x1" Bar Stock and a couple of C-Clamps
to make a fence on my milling table.  This will help a lot when I am
spotting the NeoMag8.  I have had significant trouble trying to square
things up on a drill press table.  The post is round, with no markings,
and the Head is so far away from the base that there is no common
reference.  This is why I need a mill, or at least a better drill press.
I was thinking about getting a laser line generator, and attaching it
to the head of the drill press somehow.  This will help me square the
head to the table at least.  A legitimate mill would have reference
points and locks to sit square, solid...

z.monkey

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Re: Dia. Mag. Alternator
« Reply #217 on: July 06, 2011, 06:42:24 PM »
What luck...

I've been whining about magnet prices today.  I had based the NeoMag8
on some magnets that I found at Magcraft...

http://www.rare-earth-magnets.com/p-36-nsn0625.aspx

When I first sourced these magnets they were $10.99 a pair.  Then recently
I went to order them and they were $16.99 a pair!  So that started the
rampage to find an alternate supplier...

I found some arc magnets at CMS Magnet that are the same size, on sale, $6.89
for a pair...

http://www.magnet4sale.com/On-Sale-2-PC-Neodymium-Magnets-N42SH-OD2.00XID1.75XL1.0-X45-Degree.html

So, now I have the magnets for NeoMag8 on order, better get back to shredding metal...

z.monkey

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Re: Dia. Mag. Alternator
« Reply #218 on: July 08, 2011, 01:03:09 PM »
OK, now spotting DiaMag8...

I have all the plates and the sacrificial block squared up with the fence.
I am using a regular 1/8 inch drill bit for spotting this time.  The 1/8"
mill that I normally use only has a 3/8 inch length of cut.  The stack
of DiaMag8 plates is 1/2 inch thick and I want to punch down into
the sacrificial block as well.  This is also the tallest stack of plates
that I have put on the Palmgren Table.  I am just about at the limit
of the vertical clearance on my Mini Mill setup...

The fence was very helpful in getting the workpieces squared up...

z.monkey

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Re: Dia. Mag. Alternator
« Reply #219 on: July 12, 2011, 02:01:14 AM »
Finally got the new rotor magnets for DiaMag8...

z.monkey

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Re: Dia. Mag. Alternator
« Reply #220 on: July 13, 2011, 04:52:21 AM »
I sliced a one inch section from the aluminum round stock.
Got nicely squared up, and marked up, and sank the shaft hole.
Typically you would want to do this on a lathe, because you
want a shaft to be dead nuts center.  Well, I ain't got a lathe,
so approximated as well as I could with the drill press.  The
runout is about 20 to 30 mils,  which is not great.  I haven't
measured it precisely yet, tho...

Cutting a 1.75 inch piece of bar stock with a hack saw was
super, extra fun too...

z.monkey

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Re: Dia. Mag. Alternator
« Reply #221 on: July 15, 2011, 11:00:30 PM »
That first rotor (left) was too wobbly, so I made a couple more.
This time I went to a friends machine shop and used a
lathe to cut the center hole.  No more wobbles.  I also
changed the position and size of the peripheral holes.
They reduce the weight and add ventilation through
the rotor.  I am going to add a small fan on one side of
the rotor to pump air through the rotor for cooling.
Don't want my fancy Neo Mags overheating...
« Last Edit: July 16, 2011, 12:23:34 AM by z.monkey »

z.monkey

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Re: Dia. Mag. Alternator
« Reply #222 on: July 16, 2011, 02:59:46 AM »
Spotting...

I have had a lot of trouble getting this concept...

X marks the spot.  Got to hit it perfect...

All the accuracy hangs on this event.  I've had
a crash course in spotting over this week.  Yeah,
uh, gotta have the right tools.  A spotting drill,
a short, stubby, sharp angled drill/mill can help
you hit those X's with zeal...

Also beware of cheap center punches.  Use a
hardened punch with an angle that matches
your Drill/mill.  Then the dimensional tolerances
can be happy...
« Last Edit: July 16, 2011, 03:37:38 AM by z.monkey »

z.monkey

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Re: Dia. Mag. Alternator
« Reply #223 on: July 19, 2011, 04:29:47 PM »
Got the stack spotted.  The first picture has drills in the 1/4 inch holes to show
parallelism.  Then I bored out the center holes to 1/2 inch individually.  The
stack also pictured there has all four plates on it.  I'll only cut two at a time.
First I'll cut the wire form plates, and then the bearing plates.

This time I am using a 1/2 inch center post in the cutting process.  Same as before
where I'll make a special post I can jam into the table, and that becomes the
fourth axis in the process.
« Last Edit: July 20, 2011, 02:51:47 AM by z.monkey »

z.monkey

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Re: Dia. Mag. Alternator
« Reply #224 on: July 20, 2011, 06:28:47 PM »
Yesterday I ordered some more clamping accessories for the Palmgren
table.  The corner bolts on DiaMag8 are 1/4 inch, and the smallest clamping
studs that I have are 3/8 inch.  Also the smallest hole in the T-Slot Nuts
is 3/8".  I can get T-Slot Nuts that have 1/4 inch nuts, but they are too narrow
for the Palmgren table.  So I bought some threaded inserts that are 3/8-16
outside threads and 1/4-20 inside threads to achieve the goal of having
1/4 inch clamping studs.  Should have those today, and then I can start
cutting the DiaMag8 plates.

In the meanwhile I prepared the Music Wire shafts for the Rotors.  Music
Wire is an extremely hard carbon steel used for shafts.  I had to use a
Tungsten Carbide Grit Saw to cut it.  I mounted the Rotors on the Shafts
with an Interference Fit.  The hole in the Rotor is 0.250 inches and the
Shaft is 0.251 inches.  I ground the Shaft slightly, like 0.0005 inches, and press
fit the Shaft on the Rotor.  That means I held the Rotor in top of the
vise, and tapped the Shaft into the desired position with the Blacksmith
Hammer.  Both Shafts fit well, thoroughly lodged in the Rotors, although
one was slightly easier to mount, slightly smaller shaft.  This way we
don't mess up the balance with a hole and a set screw.  Also no set
screw to come loose and get lost, and no hole play tolerances.  The
Shaft and the Rotor are basically a single piece now.

I was thinking about Temperature Mounting the Rotor and Bearings on
the shaft, but found out that I can't put the sealed bearings in a hot
oil bath (300 degree Fahrenheit Oil) without damaging the seals.  In a
Thermal Mounting Process you would cryogenically freeze the inner part
to negative 300 degrees Fahrenheit and heat the outer part to positive
300 degrees Fahrenheit, and then put them together.  As the differential
temperatures balance the inner part expands and the outer part shrinks,
leaving a tight interference fit between the parts.  I did something similar
but with mechanical force, and not temperature, but the result is the
same.  And, no I didn't mushroom the end of the shaft hitting it with the
Blacksmith Hammer.  The Music Wire Shaft is much harder than the
Blacksmith Hammer.  There are actually dents in the face of the Blacksmith
Hammer now.

So, after getting the Shafts mounted I needed to make some spacers to
act as standoffs for the Bearings.  They are 1/4 inch inside diameter
Aluminum Tubes, 3/8 inch outside diameter, cut to 0.750 inches long.
They fit between the Rotor and the Bearings to provide spacing for
the windings.  Then the Bearings are also interference fitted to the Shaft.
The very last thing to do to the Rotating Assembly is to mount the
Magnet Arc Segments, which I'll do with some Industrial Epoxy.

Also there was the Center Stud I needed to fabricate.  This is a non-standard
method which I am using to get around buying more tools at the moment.
I cut a 3 inch long piece of 1/2-13 threaded rod, a little longer than what
is needed.  Then I ground down about a 1/2 inch of threads on one end in
order for the Center Stud to be able to pass thorough the end of the
T-Slot Nut.  Then it can be jammed into the table to act as the Forth Axis.