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

[Orjan72]

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

 

[zeeprogrammer]

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

 

[Blogwitch]

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

 

[Orjan72]

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

 

[Orjan72]

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

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

 

[Orjan72]

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

 

[Maryak]

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

 

[Orjan72]

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

 

[Orjan72]

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

 

[Maryak]

Nice work Orjan. :bow: :bow:

Best Regards
Bob

 

[Orjan72]

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

 

[Orjan72]

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

 

[Maryak]

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

 

[Blogwitch]

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

 

[Orjan72]

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

 

[Blogwitch]

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

 

[Orjan72]

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

 

[Stan]

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.

 

[Orjan72]

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

 

[Foozer]

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