Steam turbine generator

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rkcarguy
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Re: Steam turbine generator

Post by rkcarguy »

Prior to the days of lithium batteries and brushless motors in the RC car world, I had played with winding my own armatures and also had a little lathe for the turning the commutators. I was able to statically balance the armatures by letting them rotate freely in the lathe on their bearings while applying a little PC-7 epoxy to the windings. It was not perfect, but got them pretty close. After it cured, it could be fine tuned by repeating the procedure again and removing a touch of the epoxy with a dremel. My '"speedway" wind ended up running almost 54,000rpm but at a lower amp draw than other off the shelf motors that my competitors couldn't make run time with. Coupled with a good setup, I dominated the open class, and the motor held together until I moved on from the hobby and it became obsolete.
The high efficiency of the new drone motors have lots of potential retrofitted into a steam generator case, I'll be watching this thread to see how it goes.

Btw, check out this on Ebay. Tiger Motor 1306's, 12 each for $250, over 1,300 in stock.
https://www.ebay.com/itm/233679735404?m ... aad8f50684
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dusty
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Re: Steam turbine generator

Post by dusty »

rkcarguy wrote: Fri Sep 10, 2021 1:28 pm <snip>

I was able to statically balance the armatures by letting them rotate freely in the lathe on their bearings while applying a little PC-7 epoxy to the windings. It was not perfect, but got them pretty close.

<snip>
Apparently, there's now a way to dynamically balance motors (or generators) using a smart phone running a vibration app. I have only seen this demonstrated on the following YouTube video and have not used this method myself, but it looks very useful. I will certainly be giving this technique a try on my steam turbine before I spin it up to full rpm. https://www.youtube.com/watch?v=RItntpZZH4g
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Dick_Morris
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Re: Steam turbine generator

Post by Dick_Morris »

Dusty Very interesting. Not only will this allow the generator portion to be balanced, but it makes the idea of an investment cast wheel a lot more achievable

Did you notice that the video is eight years old, so the capability has been around for a while. (But this is the first time I've heard of it.)
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Dick_Morris
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Re: Steam turbine generator

Post by Dick_Morris »

I have been surprised that I hadn't been able to find good photos of a K-240 on the Internet, so for posterity and for the one or two people who might actually want to build one I offer up these photos taken at the ARR 557 Engine House this morning.
Attachments
Pyle-National k-240 turbo generator, generator end. Engine 557 Restoration Company Photo.
Pyle-National k-240 turbo generator, generator end. Engine 557 Restoration Company Photo.
Pyle-National k-240 turbo generator, side 1. Engine 557 Restoration Company Photo.
Pyle-National k-240 turbo generator, side 1. Engine 557 Restoration Company Photo.
Pyle-National k-240 turbo generator, side 2. Engine 557 Restoration Company Photo.
Pyle-National k-240 turbo generator, side 2. Engine 557 Restoration Company Photo.
Pyle-National k-240 turbo generator, generator top. Engine 557 Restoration Company Photo.
Pyle-National k-240 turbo generator, generator top. Engine 557 Restoration Company Photo.
Pyle-National k-240 turbo generator, turbine end generator end. Engine 557 Restoration Company Photo.
Pyle-National k-240 turbo generator, turbine end generator end. Engine 557 Restoration Company Photo.
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Dick_Morris
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Re: Steam turbine generator

Post by Dick_Morris »

Btw, check out this on Ebay. Tiger Motor 1306's, 12 each for $250, over 1,300 in stock.
https://www.ebay.com/itm/233679735404?m ... aad8f50684
This may be a situation of let the buyer beware. There are a number of vendors who list this motor but they are all out of stock. I have also read a number of posts saying that knock offs of the popular motors is rampant.
rkcarguy
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Re: Steam turbine generator

Post by rkcarguy »

Dick_Morris wrote: Sat Sep 11, 2021 1:35 am Dusty Very interesting. Not only will this allow the generator portion to be balanced, but it makes the idea of an investment cast wheel a lot more achievable

Did you notice that the video is eight years old, so the capability has been around for a while. (But this is the first time I've heard of it.)
I don't think I'd want to spin a casting up to the RPM these will see. Just my opinion. I think I'd want a machined billet part or a forging. Granted if it comes apart it's not likely to explode out of the case and injure anyone, but all the hard work turned into a paperweight wouldn't be so wonderful.
If you feel the Ebay link motors are poor quality knock off's, please remove.
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Dick_Morris
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Re: Steam turbine generator

Post by Dick_Morris »

Although it is a point worth considering, the turbine wheel on my generator will be less than an inch in diameter so the forces are comparatively small. Motors of this size drive a plastic prop at the same speed that are three inches in diameter which I have to assume are fairly reliable. I have thought about doing some testing of the design of a 3d printed turbine wheel but would turn it at only a small fraction of the design speed of the motors.

I don't know that there is a problem with the Ebay motors, and I wouldn't mind having a couple to test if I didn't have to buy a dozen, but I wanted to share the general caution on knock offs that I found in several places while doing my research.
Last edited by Dick_Morris on Mon Sep 25, 2023 5:43 am, edited 2 times in total.
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dusty
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Re: Steam turbine generator

Post by dusty »

rkcarguy wrote: Mon Sep 13, 2021 3:32 pm
I don't think I'd want to spin a casting up to the RPM these will see. Just my opinion. I think I'd want a machined billet part or a forging.
<snip>
Castings vs Forged metals; interesting sub-topic for this thread. In general, I agree that castings are weaker than parts made from forged metals, but that doesn't mean that castings are too weak to be used. Nearly all centrifugal impellors (aka Compressor wheels) along with the hot section turbine wheels found in automotive turbochargers are castings, which would seem to validate the use of castings in high rpm applications.
rkcarguy
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Re: Steam turbine generator

Post by rkcarguy »

I've been through several turbochargers. The ones I worked on had a hot side wheel that was one part with the shaft, and appeared to be forged steel to me. There was a hex which had been machined on the top of the hot side wheel, and then part of it had been ground off to balance it.
The compressor side was aluminum and had an extruded look to it.
I have seen some others like the OEM Turbo used on the Cummins, which appeared to possibly have a cast hot side.
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Steamer Al
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Re: Steam turbine generator

Post by Steamer Al »

Also interesting to note that some of the compressor blades in modern high bypass turbofan engines on airliners are investment cast. Althought Im sure its an alloy we could only dream of getting ahold of!

https://www.foundrymag.com/molds-cores/ ... ine-blades
rrnut-2
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Re: Steam turbine generator

Post by rrnut-2 »

That hex is cast in. The investment casting foundry that my wife works at makes those turbo wheels, both ends.
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Bill Shields
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Re: Steam turbine generator

Post by Bill Shields »

Steamer Al wrote: Tue Sep 14, 2021 2:33 pm Also interesting to note that some of the compressor blades in modern high bypass turbofan engines on airliners are investment cast. Althought Im sure its an alloy we could only dream of getting ahold of!

https://www.foundrymag.com/molds-cores/ ... ine-blades
You are correct about the cast turbine blades but any comparison of that process (or material) to any type if casting available to hobbiests is like comparing a Model T to the Space shuttle.

Nothing wrong with a correctly cast wheel.
Too many things going on to bother listing them.
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