Arnold's small turbine

[arnoldb]

Thanks Jim :big: - the drink does help with that - but the surprise the next morning is a double whammy - both a hangover and an ugly woman!
As to the torque,on low RPM there's not much... I didn't check on high RPM - but thanks for the reminder on torque; there's something I need to add!

Thanks Dave ;D

Robert, if I leave my glasses of, I can't see enough to differentiate between female and male, and that's a really scary thought :big:

Thank you Diy89


ADDENDUM TO THE BUILD:
Jim's question about torque reminded me of something I wanted to note when I started on the build. As stated, the build is loosely along Elmer's turbine plans, but I actually made it a mirror image of his design.

For anybody that builds Elmer's turbine as designed, I feel there is a very real possibility of the nut retaining the rotor unscrewing if the bearing seizes up or there is a load running on the pulley and the engine spins up under pressure. The turning direction of the rotor in his design is the same direction as needed to unscrew the retaining nut. If that comes of at a couple of thousand rpm, it could be a tad dangerous.

With the mirrored version I built, the rotor will tend to tighten the nut further - hopefully keeping things together and just shutting down the turbine if something goes wrong. No guarantee for safe operation though, but at least a little extra comfort.

And for the record, the above is said with the greatest respect to Elmer and his legacy.

Kind regards, Arnold

 

[DaveH]

Arnold,

Another thing I would like to comment on are your photographs.
Excellent ;D

I'm going to post a question about photography - I would appreciate your comments.

Dave

 

[lazylathe]

Very cool Arnold!!!

Love the sound the turbines make!!!

As i remember, the saying goes:

Nice from far, but far from nice! :big:

Andrew

 

[bearcar1]

Yes I agree with you Arnold, in my younger and less 'regimented' days there were a few of the "Oh My GOD!!!! What have I done ??? " moments, but *ahem* that was in the past.

As to the axle retaining nut working itself loose, one would have thought that Elmer would have taken this into account and provided for a means of preventing just such an occurrence from happening. I like your cure for this potentially dangerous situation. always thinking you are (yeah, except for the mud fences that cajole along once in a while Rof})

Another thought came to my mind(?) :shrug:, would there be any advantage in making the fins deeper or thinner (more vanes)? Or perhaps a different angle placement of the air inlet nozzle for higher efficiency, not that in this instance one would ever be in need of such parameters, it's just more for curiosity aspects of the subject than anything else. Again, well done.

BC1
Jim

 

[b.lindsey]

Arnold,
I have been following along on this one and needlelss to say the results are inspiring from near or far!!! Great little addition for your collection and such a nice finish also...not sure I have the patience for that much bling...lol.

Regards,

Bill

 

[Maryak]

Arnold,

Congratulations another beautiful model. :bow: :bow:

By my reckoning that's 2, 2 models to you - 2 parts of a model to me, not to mention the various tools as well. ;D

Best Regards
Bob

 

[doc1955]

Nice little turbine Arnold!

And I like the dremel and polishing tip I think to my self (self why didn't you think of that!) Duh.
I have -q- tips in the shop all the time and clip them in half and the do make nice little polishing buffs. Thanks for that tip you get a Karma

 

[Chaffe]

Looking very good! like the polished finish, im guessing its doing around 50-100 thousand rpm, which may mean your drive pulley is a little big! a very low friction 100/1 or more worm reduction, and i think this turbine could do some "work". great stuff, look forward to more posts!

 

[Noitoen]

All you need now is a ball governor to regulate the speed ;D ;D

 

[Chaffe]

All you need now is a ball governor to regulate the speed ;D ;D

lol, i wouldnt stand near that! take your eye out if they came loose :hDe:

 

[BillC]

Arnold,

Neat! Just thinking: had you thought about a planetary reduction for the output? Something like 3:1 or 4:1 wouldn't be a large gearcase but would bring the pulley speed down a considerable amount....Just sharing a thought...

BillC

 

[Ken I]

Bill C - great idea - how about the double reduction planetary gear set from an old cordless screwdriver. (I have a few dead ones lying around - special offers are generally cheaper than a replacement battery pack).

Nice little turbine Arnold.

Ken

 

[BillC]

Battery packs seem rule the world.... but yes, good source for a 'prefabricated' gear reduction set.

 

[arnoldb]

Thanks Dave - I'm a bit late to posting on the photos now

Andrew, Thanks - yes; it is "Mooi van ver en ver van mooi" ;D

Jim, "ahem" - Yesterday is in the past as well .
From the limited research I've done on turbines so far, all of the factors you mention have a contribution. In fact, I think this one would have run better with less vanes. The air nozzle direction also plays a big part; I think mine is a bit too high. For now I'll leave it as is - except for making a base. Other projects are waiting ;D; this was just a quick diversion to brush up and try out some tooling techniques.

Thank you Bill. The bling was pretty quick actually; literally just an hour or so. What took the time was getting rid of most of the tool marks!

Thanks Bob, I appreciate your support ;D - Don't mind me; it's all just bees in my bonnet - and your shop's a bit inconvenient at the moment.

Doc, thanks. And a pleasure; polishing in the corners had me puzzled as well; a good night's sleep sorted that out ;D

Thanks Chaffe. I don't think that was much over 20k rpm though. And that's plenty enough for me; I'm a scaredy-cat! I'll leave the pulley as-is for now; I don't really intend to drive anything with it.

:big:, Helder, I don't think I have the balls for that one - the governor will have to wait for a horizontal mill engine, or even better, a Corliss ;D

Thank you Bill C; good idea. Hmm - I only thought of a worm reduction. Maybe one day when I feel like making some small gears

Thanks Ken ;D

Kind regards, Arnold

 

[coopertje]

Looks really good Arnold! Very nice build and i love the sound of rpm ;D

Thanks for sharing it with us.

Regards Jeroen

 

[tel]

Nice one Arnold, and fast too!

If you were going to gear down the output it might pay to have a belt drive in the first stage? Even 20k seems offal fast for gears.

 

[BillC]

Nice one Arnold, and fast too!

If you were going to gear down the output it might pay to have a belt drive in the first stage? Even 20k seems offal fast for gears.

That's a very good point, tel. Gears get hot and sticky - unless cooled. Maybe channel some of the exhaust air...? What does a belt do at 20K? Look out!

 

[Ken I]

Power take off from full scale turbines has always been a problem - with gears you are limited to about a maximum of 20m/sec pitch circle velocity for oil lubrication. After that you have to go to special lubicants and methods of delivery (over oiling will break teeth as the oil can't get out of the way fast enough).

But for a small scale turbine like yours driving though a 10mm PCD gear via a set of planetaries would be less than 10m/sec @ 20000 rpm which should be fine - it is a bit high to rely on grease though.

A gearset scavenged from an old cordless are often made of sintered iron which is slightly porous and retains lube well.

What rpm have you taken it to ?

Regards,
Ken

 

[Chaffe]

Nice one Arnold, and fast too!

If you were going to gear down the output it might pay to have a belt drive in the first stage? Even 20k seems offal fast for gears.

centrifugal superchargers use epicyclic gears and run at 50,000 rpm, so i think it would be ok IMO

 

[Chaffe]

Power take off from full scale turbines has always been a problem - with gears you are limited to about a maximum of 20m/sec pitch circle velocity for oil lubrication. After that you have to go to special lubicants and methods of delivery (over oiling will break teeth as the oil can't get out of the way fast enough).

But for a small scale turbine like yours driving though a 10mm PCD gear via a set of planetaries would be less than 10m/sec @ 20000 rpm which should be fine - it is a bit high to rely on grease though.

A gearset scavenged from an old cordless are often made of sintered iron which is slightly porous and retains lube well.

What rpm have you taken it to ?

Regards,
Ken

or use a worm reduction as i first said