Shop Vac Air Lift Platform

Crated with the accessories I ordered, my Smithy Super Shop weighed 850 pounds or so. The rated weight is 480 pounds at:
http://www.smithy.com/uploads/SuperShop%20PDF%20Brochure.pdf
where we read "WE SQUEEZED A 500 SQ. FT. WOOD SHOP INTO JUST 12 SQUARE FEET!"
480 pounds / 12 sq ft = 40 psf 40 psf / 144 = ~ 0.2 psi
I think my Shop Vac 222-75, an ancient metal can "The Brute", can do that; it pulls 600 watts and uses 2-1/2 inch hose. The perimeter is going to be about 192 inches, and that hose area is less than 8 sq in, so I figure the gap has to be less than 8/192 in or about 40 mils. Our floor is that flat; the Korean craftsmen worked hard scraping it by hand with two coats of grout.
I guess I'll give it a try. I have an 80 x 36 inch door and some old bicycle inner tubes. We'll see how it goes.
First, though the Shop Vac needs a roller skate bearing. You can imaging how delighted I was when I looked inside and saw that the Singer Company Motor Division chose a 608 bearing for the impeller. You can get those anywhere. Schmoopie's getting one in all stainless steel, ABEC-3, at Grainger tomorrow. I figured 3 was fine; both the class 3 and the available class 5 bearing are rated to 35,000 rpm and I just got an old variac from my trip to Boston for barn-cleaning.
Cold outside....
Warmly,
Douglas (Dana) Goncz, CPS Replikon Research Seven Corners, VA 22044-0394
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A decent shop vacuum should pull around 100 inches of water or -4 psi. Not sure what the pressure side is, should be a bit more. With that kind of pressure your door should lift 2880 pounds. The ratio of the hose to the perimeter is pretty much immaterial as long as it can maintain the required pressure.
The Dougster wrote:

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the structure of the skirt is critical - do a web search for home built hovercraft - there are plans for ones with a leaf blower

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wrote: (snip calculations)

Damn. The new bearing didn't change a thing. I though the loose, rusted bearing (from sucking in too much water *once*) let the commutator wobble, causing the sparking I see with loss of power. Hm. I slotted, filed, and finished the commutator. I did a spetacular job filing, finishing with a Revlon nail file. Very smooth.
My Crazy-Glue and baking soda commutator filler bars didn't last. Crazy Glue is cyanoacrylate self-polymerizing liquid.
I think I need a better filler. I have acrylic powder microballons and acrylic monomer. I think I could fill the gaps with powder first and then add monomer to all of them, but the powder falls out of the lowest gap that way. Maybe I could do it on the lathe...
Filling each gap with powder and adding monomer to only that gap is so damn hard. My hands shake. They gave me a needle applicator.
Acrylic-acrylic is better than baking soda - acrylic.
It's fun trying different repairs. I have other vacuum cleaners.
What did they use in the old days? Phenolic? I have some Glyptal spray, the high-solids motor varnish, a hazmat from MSC. Masked and sprayed into the gaps, baked properly, then turned away leaving the filled gaps, that might be best of all that I have available.
Doug
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snip

the separator between commutator segments is usually mica, it has to handle temperature. the segments are undercut a little.
If you are getting significant arcing and loss of power, you have at least one shorted armature segment - you can verify this with a growler.
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A shorted rotor segment? Oh. I remember the shop manual for my Jeep DJ-5A showed how to use a growler for the alternator. The rural posties had to maintain their vehicles.
A 60 Hz AC field induces current in the shorted segment only, is that right? You feel for the induced field with a thickness gage blade, or even a hacksaw blade. It "growls" when you're on the segment.
That's how it works, the way I remember it. I have such a coil, it's a poor man's "ultrasonic" cleaner; it agitates a roller skate bearing at 60 Hz in a little steel cup.
But you wrote "armature". That's the outer coil. At least I thought it was. Hm.
Tell me more, please, Bill; this is interesting.
Doug
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The Dougster wrote:

Nuh uh. The outer coil is the stator. The rotor is the armature.
http://www.sawmillcreek.org/articles/5/motor1.jpg
I pick up my experimental shop vacs cheap on Craig's List. It is *way* faster than repairing.
--Winston
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I'm not looking at _that_ motor, so I'm not arguing about that one, but you realize that there are "rotating stator" designs, also; right?
LLoyd
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Lloyd E. Sponenburgh wrote:

I'm not aware of any.
I do see 5 hits on the phrase "rotating stator motor" in Google, but three of those are duplicates that do not translate from Italian, one is a patent for a novel design and one hit is not actually in the cited text.
Nine of ten Google definitions for "stator" refer to it as the fixed, non-rotating part of the motor. (The tenth definition concerns a part for a door lock, not for a motor.)
Contrast that to 127,000 hits for the phrase "rotating field winding" as in an alternator, for example. I agree that it's field is produced by a spinning rotor or armature, not it's stator (as it is in a 'squirrel cage motor').
"Rotating Stator" appears to be one of those potentially useful concepts that never actually existed. See also:
"Civil Rights" "Management Ethics" "Budget Surplus" ...&c
--Winston
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This is an induction motor where the rotor bars are in a iron cage that surrounds the stationary cylindrical stator. The inside-out induction motor design is very common in disk drives, and was used in some high-end vinyl-record turntables. The advantages are that the flywheel and motor are combined, saving space, parts count, and (if production volume was sufficient) money.
Such motors were never a catalog item, instead being an integral part of something else, so a google search for the motor type won't much help.
Joe Gwinn
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Joseph Gwinn wrote:
(...)

Au contrare, Joe.
You describe the classical and ubiquitous 'external rotor' motor. (52,000 Google hits on the phrase '"external rotor" motor' just now)
mcmaster.com shows many examples as 'equipment cooling fans' on page 626: http://www.mcmaster.com/#electronic-equipment-cooling-fans/=4w1exy
The stator lives inside the rotor as you say. It remains fixed whilst the external rotor spins around it.
We can violently agree on that. :)
I'm not talking about 'Rotating Stator' motors, because they don't exist unless your reference frame is spinning in the opposite direction.
Stators spin only when you've lost your tail rotor.
That is operating them far outside their specifications and is not recommended. :)
--Winston
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Did you check which of the 52,000 hits were technical descriptions versus catalog offerings of motors not built into something else? (There! That'll keep him busy for 100 years.)

Cooling fans - yes I forgot to list them, and they are by far the largest volume example.

We may have gotten into a semantic tarpit, but I do recall seeing such motors in old books on electric motor design, recounting the days when every variation was tried, the winners being the stat=ndard designs of today.

Autogyro operation is in the specs, is it not?
Joe Gwinn
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Joseph Gwinn wrote:
(...)

Heh! (Too) many of them were ads from Chinese manufacturing plants. That fact saddened me so I didn't pursue it further.
(...)

Each has it's strong points. The hub motor on my bicycle is of the 'external rotor' type. Makes a compact, powerful package, it does.

Always!
--Winston
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But there is just one immense electric noodle plant that makes them all.

Also far easier to seal against dirt.

Good to know - the ground is soo far away.
Joe Gwinn
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Joseph Gwinn wrote:
(...)

That's the way it looks from here, anyway.
I suspect the country is large enough to support more than one plant. (Don't quote me on that.)
(...)

I understand that a helicopter 'engine out' recovery is one of those life - changing occurrences one hopes never to experience. I can well do without it, ThankYouVeryMuch!
--Winston
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You must be a civilian "rider". Military rotary-wing pilots practice auto-rotation landings almost constantly.
While I was an outpatient at Cam Rahn Bay airbase after a minor wound, I watched (actually) hundreds of "dead-stick" landings of UH-1s on PSP runways a week.
As a pilot myself, I get a little tickled by the civilian perception that when you crash, you die. A military is pilot is taught, "when you crash, this is what you do next...".
LLoyd
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Lloyd E. Sponenburgh wrote:

Yup. Totally. The classical 'zero timer'.

That is a reasonable thing to do. Still, takes 'Balls of Titanium'. Watching the ground come up that quickly has to be upsetting. :)

Good things to know, no doubt. I'm still trying to comprehend the '11 different kinds of altitude'.
--Winston
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The old arcade video game "Lunar Lander" did this. Best strategy was hold off firing the rocket until you'd fallen and it looked like it was a crash. There was a fuel gage, if I remember right. It was a great game, that one and Space Invaders, where you had to fire along the flanks to reduce the "step-forward" time by making the column thinner while the margins stayed the same.
Rotating stator. What would Einsein have said? Not an inertial reference frame, probably. Hawkings, though...he'd have something to say about it.
I read up before the OP and found the procedure for trimming quadrature to the applied field, but also to that field distorted by the rotor's presence *and* switched field. And I see none of that trimmability in my motor; it's running 50% or less of how it should. I'll keep at it.
Doug
Doug
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The Dougster wrote:
(...)

Not for me, even in geologically active California. I didn't suffer so much as a scratch when crashing the Lander.

Shore! It's a classical example. If you witness a 400 ton boulder spinning at 1000 RPM clockwise, first make sure that your inertial reference frame *isn't* spinning at 1000 RPM counterclockwise.

It's all relative. (Rimshot)
(...)

Excellent.
--Winston
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    [ ... ]

    I know these as "inverted rotor" motors.

    And -- interestingly enough -- they were used in the old Hunter ceiling fans. I'm not sure about the current ones, with the manufacture outsourced to China.
    I've also seen one in a mil surplus 10.5" tape deck. It had windings for three speeds, not the usual two. Then it burnt out, and I had the fun of trying to learn enough to rewind it so it would work again. I did manage -- sort of. I think that I had less torque than it originally had. But the bearings were rather old by then, and I d id not (at that time) have the equipment needed to either make a new set of sintered bronze bearings nor to re-design it to run on ball bearings.
    FWIW -- it was a cap-run motor, not a cap start one.

    Indeed so.

    Amen!
    Enjoy,         DoN.
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