Building the shrecky turbine

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Zippiot
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Post by Zippiot » Tue Jan 23, 2007 2:23 pm

I have them on the same bolt right now so it does lock them together, but once I place them on a shaft with a bolt screwing in on each side one would unscrew the other...

Cant use a standard bolt as the shaft though; bearings dont fit well on them. If they did then we wouldn't have a problem...

But if the bolts counter eachother I may need opposing threads anyways, so in order to save my project how about female threads on on side of the shaft and male on the other? That could keep it in place and I wouldnt have to make a new anything!
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Post by Zippiot » Wed Jan 24, 2007 4:25 am

Ran outta gas so I switched to flux for the few tack welds on the turbine...spattered a bit more than I'm used to.
Got the turbine red hot with a torch then dunked it, gonna temper it later but since the thing runs hot I dont know how long it will last :(

Especially since its crappy mild steel. Might pay around with nickels [coins] melt em down and cast them into little blades that I attatch to a hub. They melt around 2300 but are super strong at the running temp of the turbine. Plus each blade would cost about a nickel or less to make, which is cheap enough that I could swap them out every few hours of running!!!
I am auditing a machining class so I can play with the big lathes! They have a $50,000 lathe [cant remember brand]
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Ash Powers
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Post by Ash Powers » Thu Jan 25, 2007 12:02 am

Keep in mind, a Nickel coin is not 100% nickel. It is actually only about 25% nickel and 75% copper and wouldn't make for a very durable turbine component.

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Nickel and tempering

Post by Irvine.J » Thu Jan 25, 2007 12:12 am

Hey zippiot, just to let you know, you can actually temper stuff in OIL! Yeah no kidding, makes it ALOT harder then water. However, the tradeoff is its a bit more brittle. But maybe experiment and see which one suits you better. You can dump it in standard 2 stroke oil and that shouldn't be a problem. Just have something standing by to put out an oil fire. Though I doubt it will occure.

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Post by Zippiot » Thu Jan 25, 2007 12:16 am

I know, I did a few tests a while back. Even though its 75% copper its melting point is only 600 below that of mild steel, which might seem unsuitable for a turbine. But at the 600 C design temp the stuff can run for just as long as a mild steel blade, it is stronger while at that temp (copper has good heat qualities too but 600 C is pushing it) and its melting point puts it in the realm of stuff I can cast. While I may only get a few hours run-time out of a casted blade it is a decent, cost effective and easy method for an alternative!

I have an oil burner for my furnace also, so the fuel is cheap...free actually!

Also it gives a better chance of a uniform blade, only problem then is making a hub for them to be connected to.

A quick and easy test to see just how strong a nickel's alloy can be done with a propane torch and some pliers.
Get the nickel red hot, grab it in the pliers and try to bend it against the ground [cement]. Do the test again with 18-20 gauge mild steel. The steel is butter compared to the nickel.
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Post by Zippiot » Thu Jan 25, 2007 12:28 am

To J:
Only type O steel is tempered in oil. Type A steel is air tempd, and all the rest (with a few exceptions) work best with water.

I just did the nickel test, cut equal length and thickness strips of a nickel coin and mild steel. The steel bent at the point where the pliers grabbed it, the nickel could not be bent under the amount of pressure I was giving it (time to head back to the gym!).


Now just to make a mold out of steel and we are in buiness! Maybe make the mold out of something else, cant remember if steel refractory works with nickel and copper pours...
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Post by Zippiot » Thu Jan 25, 2007 12:36 am

Oh forgot to mention, these test are done at orange heat, somewhere between 1.5 and 1.9 K

Well in the range of the turbine!
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Post by redneck » Sat Jan 27, 2007 6:07 am

if you make an even smaller turbine, you could use valves from auto motive engines, the best ones would be ones that have been run with lots of miles on them. they would be tempered already. i reckon it would be worth a shot. older american muscle motors would be good cause they have the larger valve heads, and didnt use the multiple valves per cylinder todays foreign jobs do. maybe you could cut those then??? and cause they are gonna be kinda thin, you could make maybe 2 or 3 inline? like a full sized jet?
hooowee that was loud! do it again!

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Post by Ash Powers » Sat Jan 27, 2007 6:41 am

Interestingly enough, the Nissan 300ZX TwinTurbo (1990-1996 models) use inconel exhaust valves to hold up to the elevated EGTs.

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Post by Zippiot » Sat Jan 27, 2007 6:51 am

Thats not a bad idea, get some good quality metal already cut into a circle...

Still building 6 things at once but I have done some drawings of what the internals of the jet will be. Gonna scan that and show you all tomorrow.
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Post by redneck » Sat Jan 27, 2007 8:35 am

ok so maybe i was wrong about the foreign jobs..... but eh..... shouldnt let a bias interupt the quest for knowlage! ( spelling is on my list of quests too). however i dunno if the valves would be large enough. but hey, look into the diameters of different valves....wouldnt be hard to get specs..... on the 305/350 chevy motor i think they are about as big as a half dollar piece? been awhile since i rebuilt one of those though so i dont remember so good on that one, but maybe a ford 390 or a diesel even???? worth trying i think.... and hey man..... jets lookin good, get them pics up :)
hooowee that was loud! do it again!

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