Shop Vac Air Lift Platform

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

On Dec 7, 8:54=A0pm, I, The Dougster 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

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.

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

Nuh uh. The outer coil is the stator. The rotor is the armature.

I pick up my experimental shop vacs cheap on Craig's List. It is *way* faster than repairing.

--Winston

armature is the coil that moves, stator is the coil that does not move.

High probability that you have a bad armature

yes, you remember growler correctly

Winston fired this volley in news: snipped-for-privacy@news2.newsguy.com:

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

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

Motors in vacs are generally universal motors, and the armature rotates within the field coils (field assemly). In universal motors, the field assembly isn't usually referred to as a stator (in the USA, for as long as I can remember). Stator is a term frequently used with induction motors.

A weird little motor I saw years ago in an old dictation machine (voice recorder), where the DC motor housing was used as the drive platen for the band of recording media. In that motor, the wound armature was stationary, and the case rotated around it.

Shore it is, officially and colloquially.

Ohio, USA:

California, USA: Arizona, USA

Yup.

An external rotor 'pancake motor' as used in brushless fans, for example?

The part that holds the windings is still the 'stator' because it is fixed to the assembly. The 'outside rotor' is the type you refer to, yes?

--Winston

I really don't recall ever seeing the field coils of a universal motor called out as a stator in any parts lists. The use of the term stator that I'm used to seeing, has been associated with induction motors or automotive alternators.

I'm fairly certain that the weird platen motor in the dictation machine was a permanent magnet type DC. It was a portable model, probably made in the

60s.

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

(...)

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:

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

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

(...)

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

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

(...)

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

Congratulations Robert Piccinini and Steven A. Burd, WalMart Publicists of the Year!

Winston fired this volley in news: snipped-for-privacy@news6.newsguy.com:

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