Tesla Turbine

[Powder keg]

Hey Everyone,

I've been lurking here for a couple of weeks. I like this place.

First I'll introduce myself. I'm a full time Machinist and I love it! I have two lathes at home. A 13" X 60" LeBlond and a South Bend Junior 9" X 48". I have a Enco bench mill and a couple of welders. Ive also been building up a home foundry. The place I work just bought an older CNC mill. They have been sending me to school to learn how to run it. I've built several engines, steam and atmospheric. I've been wanting a Tesla style turbine. I love the way they sound:O).

My next project will be some patterns that I've drawn up to build my own Tesla Turbine. I plan on using CD's for the discs and bearings from small RC cars for the shaft. I'm planing on building the patterns on the CNC mill at school. I'll post some pictures of the Patterns and the castings when I get time.

Later, Wes

 

[rake60]

Welcome Wes

Rick

 

[wareagle]

Wes, welcome to the forum. We look forward to reading your posts!

W/E

 

[Cedge]

Welcome aboard Wes. Have your choice of top bunks...LOL

Steve

 

[lugnut]

Welcome Wes, I saw you handle the other day and looked at your profile, Your from Idaho it says, I am from Idaho (Lost River) and now in Oregon. Looking forward to seeing your projects. One of the great things about this forum is: you can jump in and act like you own the place and we would love it.
Welcome
Mel

 

[Powder keg]

Thanks for the warm welcome.

I decided to make three castings for this engine. They will consist of a main housing, a bearing cover, and an exhaust cover. I drew up the bearing cover with Mastercam. It has gussets and the name engraved on it. I glued up the pieces tonight. I'll machine it out of Poplar on Thursday and post some pictures. The housing Will be next. I've designed this engine it to look like it was made 100 years ago. The three gussets are S shaped like on old Flywheels. The housing will have the base cast into it. It should be a fairly easy engine to build.

Later, Wes

 

[Mcgyver]

sounds interesting Wes, i'm sure i'm not the only one who looks forward to the pics. any rpm objectives? what are you doing for bearings?

 

[Powder keg]

I'll be happy if it just runs :lol I'm using bearings from an RC car for the spindle. They will probably go out pretty soon? I have an Idea for a magnetic coupling to run a little generator of some sort. I have some Ideas that I want to try. I also might sell some castings on Ebay?

I've been casting for 4 years or so and I'm tired of casting knick nacks and such. I have a couple of small cannons, cast from Bronze, that I have just about done. I've been away from these little engines for 8 years or so and I want to get back into building them. I can post some pictures if any are interested?

Wes

 

[Bogstandard]

Welcome Wes,
Good to have you on board.
I too have designed and built a turbine, but a pocket edged one.
http://freeforums4u.com/viewtopic.php?t=244&mforum=homemodelengine

Ed Miles gave some very good advice about the bearings to use in that article.

I don't want to rain on your parade, but be very careful about using CD discs for your turbine. They are not of solid material but made up of layers that are very weakly 'stuck' together, and as soon as you penetrate the outer surface the metal foil inside will instantly oxidize and effectively delaminate the layers, making them very liable to shatter very quickly. To prove this, just get a sharp implement and 'cut' into the edge of a cd, you should find that it just delaminates very quickly and you will be able to peel it apart. If you are very careful you might be able to use the different layers for your rotors after they are delaminated, but they would be very thin. In all honesty I would use either metal or macrolon.
At the sort of speeds you are likely to encounter safety is of paramount importance, and we wouldn't want anyone being injured just for the lack of advice.
You will notice on my build that I replaced one of the end shields with a solid metal one, and the other end is 1/4" thick 'bullet proof' macrolon, all because of the safety issue involved with this type of 'engine'.

John

 

[rake60]

The great scientific minds of the MythBusters :roll: did an episode
on CD's failing at high speeds. Of course they intentionally damaged a few
to be sure they would fail, but in their test an undamaged CD blew apart
at 25,000RPM.

Someone went to the trouble of posting a video of that show on YouTube
at: [ame]http://www.youtube.com/watch?v=-c35O8mnToE[/ame]

Be safe!

Rick

 

[Bogstandard]

Rick,
I had never seen that demo, but it does tend to back up my theory about the CD being too unstable to use in this sort of engine.
My all metal turbine reaches 25K in a matter of seconds, but it does level out at around 35 to 36K because of the load of the generator (measured with an optical tacho).

John

 

[mklotz]

I've never built a Tesla turbine but, if I were to, I wouldn't even consider using CDs.
Aside from safety considerations, I wouldn't want to put that much construction effort into something that might literally explode on its first run.

Look around for some scrap hard disk platters. They're made of metal instead of plastic and are engineered to run at high rotational speeds. Since nobody repairs hard disks anymore, a local computer 'repair' facility will often have a dumpster filled with them.

The ferric oxide coating probably won't do well with steam but for compressed air they should do fine.

 

[shred]

I've never built a Tesla turbine but, if I were to, I wouldn't even consider using CDs.
Aside from safety considerations, I wouldn't want to put that much construction effort into something that might literally explode on its first run.

Look around for some scrap hard disk platters. They're made of metal instead of plastic and are engineered to run at high rotational speeds. Since nobody repairs hard disks anymore, a local computer 'repair' facility will often have a dumpster filled with them.

Just be careful to verify they're aluminum platters and not glass. Some hard drives have/had glass platters. Ouch.

FWIW, 10000-15000 RPM is about as fast as disks ever go, so beyond that you're in uncharted territory. They are fantastically well made and balanced though. Also snag the magnets while you're in there. Very good magnets, those.

 

[Powder keg]

OK, I'll reconsider the CD's. I think I have some thin aluminum lying around here somewhere?

I re-drew some of the parts on my cap last Thursday and re-did the tool paths. I'll be able to machine it tonight. There are 57,000 tool paths on this cap:O) I found out that I could add draft to my drawing. I added 4 degrees to all the vertical surfaces on my drawing. I also drew up the main housing. Hopefully I'll have some pictures soon.

Later, Wes

 

[rake60]

We're looking forward to progress pics Wes.

Rick

 

[Powder keg]

I finally got to machine the cap for my Tesla Turbine Here is a series of photos showing what happened :shock: This is the machine I used. It is a CNC router. I used double sided tape to hold it down while it was being machined.

Here is the start of many passed. There were 57,000 lines of code in the program to machine this.

A little deeper now. You can start to see the gussets forming.

Here all the roughing passes are finished. You can see how much nicer the finish passes are making things look.

The finish passes are done here. I changed the tool and am ready to engrave the name into the engine cover.

I made three passes to get rid of the "fuzz".

Here is what it looked like when the machine work was done. I think It turned out great!!!

Now lets see if a video will work?


I'll try and cast this soon. I want to see how it turns out.

Later, Wes

 

[Powder keg]

Whoa! That was a lot of pictures :lol: I think I need some suggestions on cutting out some thin aluminum discs? I'm thinking of doing it on my mill with my rotary table? I have also thought about some clamping discs on my lathe? I'll have to think about it.

Later, Wes

 

[mklotz]

Double sided carpet tape on a sacrificial plate bolted to your faceplate. A similar approach will work on the RT as well.

Superglue is a possibility too. Soak with acetone to release or use gentle heat. A hot air gun works well.

 

[Powder keg]

I'll try the Superglue trick. I'd worry about bending the discs trying to get them free of the tape.

I have the case drawn up and will finish it and the toolpaths Thursday. I'll take plenty of pictures when I get it done. I think this will be a fun engine.

Later, Wes

 

[Bogstandard]

Have a look at my post here
http://freeforums4u.com/viewtopic.php?t=228&mforum=homemodelengine
Look at the bit about friction turning and instead of drilling the centre, make up a turned slug with a centre and use that between the rotating centre and the discs. Put two very small bits of double sided tape ( about 1/4" square) on opposing sides of the discs, out towards the edge, between each one. Make a lot more than you need, maybe 20%.
Once you have the pack to size you should be able to hold them in your outside jaws to put the centre hole thru.
To get them apart, just drop them into white spirits (don't know the american term), the spirits used for cleaning brushes after painting glosswork around the house. They should just fall apart.

John