# Tesla Waterpump/turbine- My first project. (Was fingertreadle engine)



## Orjan72 (Mar 12, 2010)

Here are some pics of my first project.
I chose a finger treadle engine because it is very simple, I get to turn a flywheel , axel and crank and I get a visible result of my training.
Unfortunately my shop is rather limitet (I'm working on that one ;-) ) and I spend all my consentration on getting it right, forgetting to take photos at every step. However, here are some pics of my first mandrel. I needed to make a mandrel to finish my flywheel and my first attempt in axel steel failed. I think I know why though. I still use the original toolpost and it leaves me with a too high placed tool. It rubbs. I bought a Quantum, QCTP, but the size was wrong from the dealer and I'm waiting for a replacement. I tried shimming the rear of the tool, but that is only partly successful as I get an weird cutting angle and a rough result in steel. The alu mandrel didn't last long, the threads broke and the flywheel came loose just as I finished a cut. I learned a lot from the excersize and even modified a drillbit to cut brass, following a tip on this site. Worked beautifully!

Onwards and upwards!

Orjan


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## zeeprogrammer (Mar 12, 2010)

The flywheel looks good.
I've wanted to do a finger-treadle engine too. Are you working from plans?


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## Blogwitch (Mar 12, 2010)

Orjan,

If you can take a little advice from someone who has made a couple of these. Get as much mass as you can onto the outside of the flywheel, even if it means thinning down a little where the spokes normally go. If you can't get enough to run smoothly, then consider adding some in the form of inserts or a metal tyre.

It is that part which makes for an easy runner. Too little, and you will struggle to keep it going for any length of time.


Bogs


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## Orjan72 (Mar 12, 2010)

zeeprogrammer  said:
			
		

> The flywheel looks good.
> I've wanted to do a finger-treadle engine too. Are you working from plans?



No I'm making it up as I go along. Although I take tips from several plans/designs I have seen.

Orjan


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## Orjan72 (Mar 12, 2010)

Bogstandard  said:
			
		

> Orjan,
> 
> If you can take a little advice from someone who has made a couple of these. Get as much mass as you can onto the outside of the flywheel, even if it means thinning down a little where the spokes normally go. If you can't get enough to run smoothly, then consider adding some in the form of inserts or a metal tyre.
> 
> ...



Excellent! I'll make a note of it. I think my flywheel is a bit off... too thin rim and too thick center. Might save it if I shave of a bit of the center. It's quite heavy but I fear , as you say, in the wrong place.

thanks for the advice!

Orjan


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## Orjan72 (Mar 13, 2010)

Ok, bit of a change.
I just got some aluminum today, and the size was 70mmØ x 200mm. It's so nice to have good friends who will go through the scap bins at work for you. Especially when they turn up stuff like this. I even got 3 of them ;D

WARNING non engine project!
If this project is sort of on the sideline for this forum I will refrain from posting any log of it. If however you find it interesting I will post a build log as best I can.

So, I have had plans to make a Tesla waterpump for a while. Now I got the material and I can't wait. So I got going today.
Made som rough plans from looking at a guy demonstrating his pump on Youtube. Im going bigger, hoping to lower the revs and still getting good flow. 
Made the housing and prepeared to part into 3. 
Will bore the parts individually as the shaft is ony anchored in one end. I will use 3 bearings to get it stable.
I haven't got a parting tool long enough to part it on the lathe, so I will saw of the parts then face and bore on the lathe.

Man, I enjoyed this evening ;D ;D
Orjan


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## Maryak (Mar 13, 2010)

Orjan72  said:
			
		

> WARNING non engine project!
> If this project is sort of on the sideline for this forum I will refrain from posting any log of it. If however you find it interesting I will post a build log as best I can.
> Orjan



Orjan,

All metalworking model projects are welcome here as are the tooling, jigs and setups which help to make it happen.

Please post a build log.

Best Regards
Bob


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## Orjan72 (Mar 14, 2010)

I got busy today and managed to part the housing. Had to use a hack saw, but I got there.
I then mounted the intake in the lathe and facet the housing side. Then peck drilled, drilled a 14mm hole through the intake and bored to dim with boring bar. I did not get all the way through, but turning the intake around and going into the pilot hole (14mm) with the boring bar I got it. The intake has a diameter of 35mm The the intake got faced and a radius taken of the inner edge.

Then I moved on to the blade housing. I faced both sides. peck drilled and bored the same way as the intake. Worked fine. I bored to 40mm in the blade housing. I will take of a radius on the intake to mate with the blade housing. But I will do that after the blade assembly is ready. That way I have some room to wriggle. 

The shaft end of the housing got faced and thats it. I need to figure out my exact dimentions before boring. as well as the layout and arrangement of the bearings. I need some low friction bearings to fit a 5 to 8 mm shaft, with an outer diameter of no more than 16mm.
I need to go windowshopping online 

I will have to figure out how to make the discs as well. Might alter something that fits the bill, because machining discs with dim:40mmØ and 2m thick might be a tall order... at least for me. 

Onwards and upwards!
Orjan


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## Orjan72 (Mar 15, 2010)

Got going on the shaft part of the housing today. Bored to 25mmØ and then made a brass sleeve with a retention ring on the disc side. I had a problem with my cross slide longditudenal feed, it was ever so slightly out of position and I got 0.2 taper on the through-hole for the bearings. Might have to go up one size in bearings to fix it, or make a new sleeve.
I vill make a brass nut to lock the sleeve i place and retain the bearing. All in all, some progress has been made... 

Upwards and onwards

Orjan


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## Maryak (Mar 16, 2010)

Nice work Orjan. :bow: :bow:

Best Regards
Bob


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## Orjan72 (Mar 16, 2010)

Thanks Bob!

Until 3 weeks ago I had never touched a lathe before, but now I'm having more fun than is legal.
Working out my own design and technical solutions is great fun, and the learning curve is steep. 
The machining has gone without big mishaps, but I suspect that some of my more creative work methods aren't best practise among machinists. I'll have to think every operation through before starting to avoid basic and serious mistakes.

I think I need a mill.... :

Orjan72


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## Orjan72 (Mar 19, 2010)

Hi everybody!

I need some assistance in the ball bearing department :wall:. Having very little knowledge of them I need some input on my initial thoughts:

The shaft will be supported only in one end of the housing and hanging free in the intake end. This calls for a minimum of 2 bearings, but a third thrust bearing close to the central water/disc part of the housing might be in order. 

As this pump is made of discs I expect very little in the way of radial forces as well as thrust forces, but if I decide to reverse it and use it as a turbine it will most likely reach quite high RPM (10 000RPM +) :hDe: . I would therefore probably need some low friction/high RPM bearings. The speed rating will probably be more significant than ability to harness forces. 

The shaft will be between 5mm and 8mm Ø. and about 100mm long. I plan to shave of the diameter to create flanges for the bearings to lock against towards the watersection of the housing and a lock nut on the input/power side. The outer diameter is 20mm for the bearing. Any thoughts on my rationale is greatly appreciated as well as tips on where to get hold of the mysterious bearings 

Have in mind that I'm a newbie, quite out of my league here, and might not at all know what I'm on about! 

Orjan


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## Maryak (Mar 19, 2010)

Orjan72  said:
			
		

> The shaft will be between 5mm and 8mm Ø. and about 100mm long. I plan to shave of the diameter to create flanges for the bearings to lock against towards the watersection of the housing and a lock nut on the input/power side. The outer diameter is 20mm for the bearing. Any thoughts on my rationale is greatly appreciated as well as tips on where to get hold of the mysterious bearings
> 
> Orjan



Orjan,

I can't help with the bearings but at the high rpm you envisage, the lock nut will need some form of securing or a thread of the appropriate hand to ensure it can't come loose.

Hope this helps a little.

Best Regards
Bob


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## Blogwitch (Mar 19, 2010)

Orjan,

I don't think you need to worry too much about the bearings you need to use. At the sizes and RPM range you envisage, they should be well within your safety limit.

10K RPM is rather low, and the 6mm internal diameter standard flanged bearings I used on my air turbines were rated at 39K RPM with grease lube, and slightly higher with oil. I used the grease lube, as the difference in RPM wouldn't have made much difference. If I needed to go much faster, then I would have had to use very expensive ceramic bearings.

I would suggest that you use stainless ones for obvious reasons.

Bogs


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## Orjan72 (Mar 19, 2010)

Hi Bog,

Good info!
Looking at you numbers I see what you mean. I'll go ahead and get some SS standard sealed bearings and try it out. My design alows for me to make several bearing housing/brass inserts of various internal design and try them out without having to redesign the external housing itself. 
Thanks for the tip!

I got a good tip from a maintenance engineer at work of making a bearing housing in a stepped design. that way I get a good way to secure the simmring and the bearings. I had originally thought to secure them with an internal spacer tube that rested against the outer stationary rings of the bearings. But stepping the housing and securing with locktite or even a spacertube would probably be as good if not better.

Next challenge is to make the discs.
They need to be 40mmØ 1,5mm thick and absolutely straight.
Could be brass, could be steel or aluminium.
Aluminium would give it low inertia on startup, but will be very sensetive to deformation.
SS would be nice, but hard to machine...

Any thoughts? I'm open to using existing components and adapting for my use.

Orjan


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## Blogwitch (Mar 19, 2010)

This is one of my old topics, and could be a way for you to make the discs you require

http://www.homemodelenginemachinist.com/index.php?topic=1510.0

Bogs


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## Orjan72 (Mar 20, 2010)

Good stuff, thanks Bog!
I'm now kicking myself for not thinking of it myself 
I'll try that approach when I start on the discs. Will try sheet metal first.

Todat I got going on an attemp on the shaft assembly. I failed miserably. I should have known and waitet untill my Qctp arrived so I could alligne my tool properly. 
The result: Shaft too rough and uneven in diameter, Thread off kilter and makes the spindle wobble, sleeve too loose and bearings not secure, Parting tool broken due to too low cut. :'(

Right, new plan and a more patient approach needed.

I will hold off on the precision work till I get the QCTP.

Need to get new insert for parting tool and possibly new partingtool all together (one with longer reach)

I'll look into getting sheets for the discs this week. Maybe I'll have more luck with that.

Onwards and upwards, or possibly sideways.

Orjan


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## Stan (Mar 21, 2010)

Several years ago, HSM ran plans for a Tesla power turbine. The writeup said that the efficiency was a function of the surface finish on the discs. At a scrap metal yard, I found some SS with mirror finish on both sides that I used. No other experience but it certainly works well with low air volume to bring it up to 9k RPM.


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## Orjan72 (Mar 21, 2010)

Hi Stan,

Yes I heard that too, for the boundry layer effect/coandi effect to work it's magic it's important to polish the discs to perfection. any grooves or coarse surface creates turbulence and performance is reduced.
SS is a good way to go as they are more likely to last in a "humid" : environment.
I thought I would follow Bostandards tip and make the discs from sheet . Then polish.

Thanks for looking in and giving me your 2c 
Orjan


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## Foozer (Mar 21, 2010)

Orjan72  said:
			
		

> Right, new plan and a more patient approach needed.



Know the feeling, done many of those OOPS moves. Tis what i like about this hobby, the submission to patience, less the scrap pile consumes the efforts.

Have learned over the years when that hurry up voice is heard tis time to put the tools down. The ol "Just have this one thing to do" usually creates the biggest errors.

Like that turbine tho, keep thinking to build one myself, might just be within my skill zone.

Robert


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## Blogwitch (Mar 21, 2010)

Orjan,

If you have an old hard drive, I reckon the plattens out of it would be perfect for your discs and if you are careful, they will be super highly polished, saving you a job. If you can get the bearings out as well, they might be good for use as well.


Bogs


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## Orjan72 (Mar 21, 2010)

Foozer  said:
			
		

> Like that turbine tho, keep thinking to build one myself, might just be within my skill zone.
> 
> Robert



If I can do it, everyone can :big:
Get going, 
Orjan


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## Orjan72 (Mar 21, 2010)

Bogstandard  said:
			
		

> Orjan,
> 
> If you have an old hard drive, I reckon the plattens out of it would be perfect for your discs and if you are careful, they will be super highly polished, saving you a job. If you can get the bearings out as well, they might be good for use as well.
> 
> ...



Good thinking, I havent got any old drives laying about, but I think I know where to get some.
Doesen't hurt to have a look. Will scounge around, I might get lucky. If i get ready polished discs out of it It would be great.

Thanks for the tip!
Orjan


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## Cheshire Steve (Mar 21, 2010)

I have a stack of hard drive disks here, with thoughts about a Tesla turbine in mind for the distant future. They look like chrome plated, but I suppose the finish must be a magnetic oxide, and who knows what underneath. OK if air is your driving medium. The bearings aren't really accessible being built into a central motor/bearing units. There are a couple of wicked magnets in each drive too.

One things about the Teslas is they tend to spin very fast which can be a test for the materials and bearings, and I assume is a function of the inlet air flow, which will be limited by the speed of sound if the pressure is above about 25psi. By my calculations this would mean 70,000rpm for a 3.5" turbine, which could burst it. Certainly I have heard concerns about overspeed if the load comes off suddenly. I was wondering if you could use an induced air bleed to (sort of venturi effect) at the inlet to bulk up the air flow but slow the speed, so that you get rid of the overspeed potential. You would still have the same air momentum, but shared with a larger air volume, so I would think you could get as much work out of it. Maybe someone here can tell me if it is a daft idea..

Steve


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## Orjan72 (Mar 22, 2010)

Hi Steve,
Not sure if I follow, but if I do (that would be a first...) ;D ,
Enlarging the input, or making an enlarged cavity with a venturi after it would possibly give you the opposite effect. My rationale:
The cavity would get pressurized and the venturi would speed up the airflow. The cavity would be pressurized at the running pressure of the incoming air and as long as the air is replenished there would be almost no lag in the pressure when load was taken off the turbine.
However if the venturi has a smaller diameter then the inlet (nozzle into housing) it would speed up the air. If the cavity was made as a wide nozzle it would reduce the chance of overspeed by reducing the general performance capasity of the turbine. 

A flywheel would reduce the capacity for quick changes in rpm, but would result in higher inertia and possibly reduced overall performance. Maybe a seperate airchamber, sealed from the airflow, with a radial fan that maxed out at the required top speed?
The fan would probably run into max long before you would want the turbine too....

Keep in mind that I don't really know what I'm talking about and that this is just my take on it. 

Orjan


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## Stan (Mar 22, 2010)

One other comment about the strange action of the Tesla power turbine. When it is winding up and running it sounds like a jet fighter on take off. The instant the air is shut off, it goes completely silent, unlike a normal turbine which continues to scream as it winds down.


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## Cheshire Steve (Mar 22, 2010)

That's interesting - I haven't had a chance to listen to one. I suppose it is the exit apertures that tend to make the sound. They could even act as a siren if you set them up right. I had never considered they might be noisy.

I have seen more than one safety warning on these beasties due to the extremely high speed they are capable of, and seen some rather questionable equations for the speed at which rotors fly apart. So there is a safety issue, and you need a substantial reduction gear before you let it drive anything outside the box that will fly apart at high revs.

As I think the action is mainly driven by momentum rather than pressure, I still hold that using some sort of eductor nozzle to entrain extra air might deliver similar power (momentum is conserved) but limit the top speed (velocity of the air hitting the rotors is reduced). One day I might get around to building one to test this.

Steve


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## Orjan72 (May 6, 2010)

Well, the QCTP finally arrived. It was the wrong one. Exactly the same as the one I had. 
Its all a bit frustrating as I have been waiting for it for around 2,5 months.
The dealer has offered to help out (read fix his boo boo) by machining my topslide to fit the QCTP. This means reducing the spigot on the topslide from 26mm to 20mm. Not a lot, and I see many who customize their lathes in all sorts of ways. Its just that it doesn't feel right to modify the lathe to fit the wrong part... I guess I'll go along with it and make a shim for the spigot so I can use the original toolpost as well.
He offered a compensation of some sort, I'll see what he has to offer in terms of tooling and such.

Sorry for the holdup on the build, but I cant progress with the current toolpost. It just doesent work with the tools mounted too high.
OK, enough of my ranting.
All the best for now.

Orjan


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