RE: JetJoe
 

JJ-1400 =

*Inconel Chamber
*Straight Sticks
*New Bullet Starter Unit like in previous pictures

The chamber does not look like Andys version either but just like the Standard JJ Chamber just constructed with Inconel and Straight Sticks.

Hey, call me crazy but if you want to go cheap this WORKS every time for the Turbine Wheel Nut.

http://www.golfsmith.com/products/913

RE: JetJoe
 

Thanks for the help guys. Ill take it to work and sort it out there.
It looks like my CC is made out of SS, and not inconel doesn`t it ?

What does inconel actualy look like, got a picture?

RE: JetJoe
 

I'll try and get one of the new chamber today, its a off grey and has a dull finish. Your looks to be Inconel just by the color of the exterior compared to the amount of runs you have had (?). SS tends to get real black and the sticks start flaking.

RE: JetJoe
 

Hello Per,

I tried to do some DIY hard-bearing balancing of my JJ1400 using a scope + strobe light, triggered by an analog level detector. The shaft was mounted in a jig using off-the-shelf SKF bearings. I was not very successful, to say the least. [&:] Analog electronics and phase shifts through filters is a mess unless RPM is very constant.

I improved the system using a digital setup, sampling vibration data together with revolution pickup and doing FFT calculations. This was much better. However, due to the poor jig, the measurement of vibration phase was inconsistent.

Now, I have shifted to a soft-bearing technique. I mount a vibration sensor (acceleration sensor) on the engine, and suspend the entire system on foam or rubber bands. This way the system does not change between spool-ups. Short description of the system:

-Soft bearing setup.
-Coil pickup of spinner-magnet, used as phase reference.
-Piezo acceleration sensor, and simple amplifier.
-PC with a stereo sound card.
-No analog filtering requirements. :)
-FFT of vibration signal at the frequency from coil pickup - this way, noise at other frequencies is completely irrelevant, as long as the sound card is not saturated.
-Calibration of amplitude and phase response using test weights. (calibration is a downside of soft-bearing systems)

The measurement is best at >4000RPM. I use compressed air to drive the turbine.

Tomorrow I will start the real balancing.. I have lubricated the bearings using aeroshell turbine oil - does anyone know how long it is safe to spin the engine with compressed air before lubrication "runs out"? Should I worry about that?

-Thomas

RE: JetJoe
 

Hi Thomas,

Do you have pictures of your rig? I would like to see it as I have the balancer electronics assembled from a kit from John Wells out of England. I've started machining a basic jig, but it uses teflon bearings to support the shaft and a piezo sensor to pick up the vibrations, then translate to the strobe. Seems like a bunch of people have been succesful with this set up a few years ago, but I'm sure things have improved in the home-balancing arena.

I'll be building the machinery for my jig very soon and am interested in what others have used and what peices they've sourced (motors to drive, etc.)

RE: JetJoe
 

Hi Chuck,

My first setup was using standard BB's and was made of wood. It was useless. I am sure your rig will be much much better, and I believe you will be succesful. For me, building a perfect rig was not so easy.

I will report back how good a balance I get. I hope I dont have to remove too much material. :eek:

-Thomas

RE: JetJoe
 

Skymac:

Where did you get the bullet starter assembly? did you make it yourself?? let us know!!

thanks

RE: JetJoe
 

That's the new starter from Jetjoe. You can get one for $48 from Jetjoe International, their adress in Forest Hills, NY is on the JJ homepage.
Now, the other thing they need to make is a better fuel pump. The old ones, they are like 50/50 useable and junk, and they don't last. I suspect most of the problem is the same cheapo motors that are in the starters...

RE: JetJoe
 

Well, mine had the FLIGHTWORKS pump but it also went bad, AS did the replacement for it... I also had a flightworks go bad on a simjet... What kind of luck is that?? Russ

RE: JetJoe
 

Maybe you should use a cleaner sock to filter your fuel through?

I also heard bad things about the Flightworks pumps. I'm about to buy another pump, don't know which one I will get.

RE: JetJoe
 

Moores

RE: JetJoe
 

Hi,

i make my electronic balancer using the esquematic electronic from Thomas Baumgart web site.. runs very well!
http://www.technologie-entwicklung.d...cing_tool.html

For balancing i use news and goods SKF bearings in the shaft. The pic show my first balancer version with AMT180 shaft.

Regards,

Fabio

RE: JetJoe
 

Interesting...I like the rationale behind that one, with the free floating gear, and I like the twin festos built in...
have you used that one yourself?

RE: JetJoe
 

I was swayed by Mertons engineering thought on the floating gear- I got one a while back it has been a good pump-but they all seem good till they go belly up-Its also pretty affordable given that the Canadian dollar is the only currency that is in worse shape than our own (we will of course leave the Lira out of this) Scott

RE: JetJoe
 

Fabio,

Thanks for the link - that is a really nice setup!

-Thomas

RE: JetJoe
 

Fabio,

I've got that link before and that's about exactly what I've started building with the limited milling machine I have - not near as pretty though. Did you buy the mechanics or build them? I see they're anodized a pretty purple...

The second question was going to be about the drive motor - but that doesn't look too critical and for me is about moot as my speed control is built into my strobiscopic electronics. I was/am going to mount it all onto a granite machinist's reference block for stability. What do you think?

RE: JetJoe
 

Well i have read all of this topic and all that i can say is that Experience is what matters. Find a company that has been manufacturing turbines for a couple of years and buy from them. Don’t get your self’s into problems by buying from new manufacturing companies. Looking into companies such as JetCat, Artes Jets, Baird Micro Turbines and Heward Microjets they are kind of new but I trust any one that builds engines over 400lb of thrust and sells to aerospace.

RE: JetJoe
 

Hi Chuck,

I downloaded the files (Thomas site) and i used laser cut for aluminium hardware.
the strobiscopic did not function well. I use the LED to know how much unbalancing exists. I go removing material and increasing the gain of the LED trigger until reaching the desired precision. Simple and very functional. I change the electric motor, I use now another under of the platform and turn up to 5.000 rpm.

sorry my bad english!!

Regards,

Fábio

RE: JetJoe
 

I bought two JJ's.

A JJ-1200 kit and JJ-1400 combo. Sees my pics.

Runs very nice.


Regards,

Fábio

RE: JetJoe
 

It seems my balancing works great.

However, the amount of unbalance is pretty large in my oppinion: about 1.2 cm^2 of tape.

I think I would have to remove the compressor and do some grinding on the back side. And this is where this type of balancing sucks. [&:] Who knows if the same amount of balancing is needed after reassembly..

-Thomas

RE: JetJoe
 

Fabio, o balanceador ficou excelente. como estao indo as chinesinhas ? voce esta vendendo elas
por aqui?

at+,Enrique

RE: JetJoe
 

Enrique,

é.. esse balanceador me deu muito trabalho, mas cheguei aonde queria. Vendi algumas Joe sim, mas estou pensando em parar com elas pois estou com outra atividade que me toma muito tempo, fora os consertos de turbinas importadas que ando fazendo. Acredito ser o único no Brazil Ã* ter um balanceador com precisão para nossas turbininhas.

Um abraço,

Fabio

RE: JetJoe
 

Hej Thomas,
Do you have a pic of your set up ?
Does it work okay with the sound card?
I don't have a oscilloscope but i have a freeware of a Pc-Oscilloscope that use the sound card for in put
but i don't know if it's working for this purpose.

Per

RE: JetJoe
 

Hi Fabio does your Balancer works okay?
Have you run an engine that is balanced from this construction.
I am very curious about this balancer is it easy to use?

Per

RE: JetJoe
 

Per,

Yes.. my balancer works good. Is necessary first very fine adjust. I make somes up-grade the original project. I use only one piezo pick-up and the project have two. The two piezos (push pull) no work perfect. I balanced various engines (ram's, amt's) and no problems.

The pic below is my first and original version. I go post pics the my last version tomorrow or friday.

Regards,

Fabio