Is it OK to cut the fins and tits off a squirrel cage rotor?

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shortbus= said:
I have seen really old motors like that with the copper rotor bars. But that would be a really expensive motor to make in today's world. With little to no advantage over the cast in place aluminum.
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Evidently there are some higher end motors now using copper due to the higher conductivity & efficiency, especially now with improved techniques with copper casting as opposed to the old method.
Max.
 
strantor said:
A pressure vessel is an expensive thing to make.
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I know it's like that for something containing pressure, like a boiler or industrial gas tank. But are you sure when it is used to keep pressure out? Unless this has an operator inside it.
 
shortbus= said:
I know it's like that for something containing pressure, like a boiler or industrial gas tank. But are you sure when it is used to keep pressure out? Unless this has an operator inside it.
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Oh yeah, I'm sure. We have pressure vessels on our other tools. I've seen the bills and the certs that ship with them. I've got an 87 page PDF to accompany the last one. It's pretty silly to me; it isn't like a boiler. It isn't going to explode, if anything there will be an anticlimactic implosion thousands of feet away from any person. All that's inside is electronics that don't even cost as much as the vessel.
 
I'm probably missing something, but why do you need a pressure vessel? Couldn't you just house the tool in an oil-filled flexible enclosure which naturally adapts to ambient pressure?
 
shortbus= said:
It's been my experience in life, that most of the ones with tits think they should be boss.
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Most of my bosses were boobs.

They just hung around thinking they are gods gifts to the world because they served a purpose once or twice in their life but mostly just ornamental and a constant source of pain in the back of whomever they were closest to at the time.
 
alec_t said:
I'm probably missing something, but why do you need a pressure vessel? Couldn't you just house the tool in an oil-filled flexible enclosure which naturally adapts to ambient pressure?
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I don't know where I'm failing to properly explain this... We DON'T need or want a pressure vessel. I AM designing an oil filled enclosure which naturally adapts to ambient pressure.
 
strantor said:
I AM designing an oil filled enclosure which naturally adapts to ambient pressure.
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Not trying to be combative on this. But can't see any way this, naturally adapts, will work without venting to the depth pressure. And this will change as depth changes. A vessel filled and sealed at one atmospheric pressure will still be at that pressure when the out side pressure rises. And the same laws for pressure vessel bursting pertain to pressure implosion. Both legal and physical.
 
I worked at GE motor factory once in Murfreesboro TN those tips are ejector pin holes for the die cast machine. They are left long for a reason it makes it easy to balance the rotor. Rotors spin in a machine when the red lights comes on the machine stops with the red lights on. Red light lines up with the tips that need to be shorter on the ends.

Read about the Tesla Motor your motor in oil will have oil resistance which will pull extra high idle current when the motor is not under load.
 

There is a pressure balancing diaphragm mechanism between the motor vessel and the sea water. Oil stays inand water stays out regardless of depth and relative pressures.
 
shortbus= said:
A vessel filled and sealed at one atmospheric pressure will still be at that pressure when the out side pressure rises.
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No it won´t. A pressure vessel will, but that is not what strantor wants. A vessel that is not made to withstand that pressure will simply deform until the pressure inside and outside is equal, so if you design in such deformation zone everything will be hunky dory.
 
gary350 said:
Read about the Tesla Motor your motor in oil will have oil resistance which will pull extra high idle current when the motor is not under load.
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Wouldn't the oil drag be considered a load?


As long as the motor winding are being adequately cooled by oil circulation substantial overload compared to open air operation is not a problem meaning a 10 HP rated air cooled electric motor running submerged in a bath of light viscosity oil can easily take being overloaded to the 20+ HP equivalent input power levels without winding overheat damage.

By machining the rotor down to be as smooth as possible on the exposed surfaces the overall mechanical drag will be greatly reduced. By doing that the main source of drag that will be present will be from simple surface tension between the rotor and the oil.
Taking the fins and stubs off is basically like taking an oar for a row boat and turning it 90 degrees to its normal orientation when it's in the water. Same surface area in contact with the fluid but the ability to transfer mechiacal motion energy to fluid displacement is greatly reduced.
 
tcmtech said:
There is a pressure balancing diaphragm mechanism between the motor vessel and the sea water. Oil stays inand water stays out regardless of depth and relative pressures
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kubeek said:
if you design in such deformation zone everything will be hunky dory
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Yes. It is done all the time on many bits of equipment which are intended for use subsea. It is called a Pressure Compensator.

Pressure vessels to keep subsea pressure out, are big heavy and very expensive.
If the "thing" which goes inside the pressure vessel, is able to withstand seabed pressure, then you don't need a pressure vessel.
All you need is a sealed container which sufficient strength to withstand normal mechanical loads, fill it with fluid (usually some type of oil) and have a pressure compensator which is usually a thick neoprene rubber bladder, which is filled with oil and connected to the container such that oil can move from the bladder to the container.

Then, when the whole assembly is put down on the seabed, the seawater squeezes on the bladder and the sea pressure is communicated through to the inside of the container.
Same pressure inside as outside of the container, so it does not need to be a pressure vessel.
Lighter, cheaper and everyone is happy.

JimB
 
I'm digging around in my memory and it's showing me pictures of hydraulic fluid. A subject I know hardly anything about but I think oil compresses under pressure, but with hydraulic fluid inside the motor casing it won't compress - or do so much less.
I'd have called them nipples, btw.
 
All fluids compresses as do solids. The key to working with that is understanding the relative differences in rate or ratios of compressibility and what forces are involved with each.

Even at a few thousand PSI the compressibility of common hydrocarbon fluids is not an issue being it is still only fractions of a percent of volume change.
 
There's a piece of the puzzle you're missing. I thought I discussed it, but maybe I neglected to mention the integrated accumulator. There's a collapsible bellows exposed to atmosphere which keeps the internal pressure always a few PSI higher than atmosphere via compression springs. Here's some screenshots of my current design. It's rough; I'm not done.
 
My thinking was like how they test an industrial gas or scuba tank. Where the empty tank is put in a pressure vessel. Where the tank to be tested is at atmospheric pressure and then the liquid in the vessel (water?) is pressurized and the tank pressure is then measured, to see how much the tank deforms. Didn't know there was a diaphragm/compensator involved. Wouldn't that work without filling it with oil?
 
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