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IndustryArena Forum > Hobby Projects > Hobby Discussion > balancing machine for turbine shaft!!!
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  1. #1
    Join Date
    Oct 2006
    Posts
    7

    balancing machine for turbine shaft!!!

    Hi there guys....

    I am fairly new on the site......and must say what a wonderful site this is.....

    Basically what i need from you geniuses out there is a basic balancing design for a model turbine shaft....

    I have been doing some research but not really succeeded in it....

    Is there anyway somebody can help me please....


    Thanks

  2. #2
    Join Date
    Jun 2007
    Posts
    3757

    Talking A few questions.

    turbinecrazey.

    1. How heavy is the shaft?

    2. How long is it.

    3. How do you intend to support it while balancing. Dynamic at speed I assume.

    4. How fast do want to spin it?

    5. Easiest way to drive it is a flat belt, and be able to spin it in both directions.

    6. Will you remove or add material to achieve balance?

    I class myself 'expert' in the balancing area, ego not withstanding.
    I will be able to tell you what won't work.
    Super X3. 3600rpm. Sheridan 6"x24" Lathe + more. Three ways to fix things: The right way, the other way, and maybe your way, which is possibly a faster wrong way.

  3. #3
    Join Date
    Oct 2006
    Posts
    7
    thanks so much for your reply....

    the mass of the shaft is 0.839 kg....

    the length of the shaft is 165mm....

    yes dynamic at speed....

    I would want it to spin at 120000 rpm....

    yes a have designed it to be driven by a belt but i have designed with a vee-belt....

    I would add components to the shaft....

  4. #4
    Join Date
    Jun 2007
    Posts
    3757

    Question 3?

    3. How do intend to support it while testing?

    You need to be able to press the back of a belt against it to spin it.

    While measuring the un balance it will be free spinning.
    Any drive force will introduce unwanted extra unbalance.

    Low tune. The bearing assembly has some freedom of movement radially in 1 plane. Usually horizontal.
    or
    high tune. The bearing assembly(s) react FORCE against a solid body.
    Force usually measured by ceramic piezo crystal or accelerometer.

    Do have any electronic experience?
    Super X3. 3600rpm. Sheridan 6"x24" Lathe + more. Three ways to fix things: The right way, the other way, and maybe your way, which is possibly a faster wrong way.

  5. #5
    Join Date
    Oct 2006
    Posts
    7
    i have designed the test jig...and as you explained i have accomplished everything besides the electronics....

    I have done my research and i work at a highly precision company and they are more than will to help me but no time factor....

    so basically i need to know more about where and how to mount the accelerometers....and programming...

  6. #6
    Join Date
    Jun 2007
    Posts
    3757

    Lightbulb Electronics.

    You may consider the VERY easy way to do it.

    Low tune. Allow the bearing mounts to deflect slightly. Rubber mount to bench.

    Now spin the shaft in one direction and let the support(s) deflect.
    As it is free spinning bring a felt tip marker near the shaft at the bearing and let it just touch.
    Do the same for the other end.
    Now spin it in the opposite direct and do the same with the marking pen offset slightly right or left.
    After stopping you should have two sets of marks. Average the angular position and this is the heavy spot.

    Running in both directions cancels phase errors introduced by the support system. Once you figure the phase error (possibly 30 degrees) you can just keep using the same direction nad just compensate your guessed angular position. The accuracy of the position becomes apparent. See 90 degrees below.

    As an experiment two opposed hose clips or tiewraps can be slid around to add/remove/rotate weight while experimenting.

    When the indicated position moves 90 degrees you are getting very close, and this indicates an angular error positioning the correction.

    To do this with electronics is not trivial and requires synchronous detectors and many special techniques to filter the signal from the noise.

    With a low tune system - the resonant frequency of the mounts is below the balance frequency, and the deflection is dependent on speed, unbalance and the mass of the workpiece. Calibration is a bit hit and miss.

    With a high tune system - the resonant frequency of the mounts is above the balance frequency, and the force measured is dependent proportional to 1/speed squared and the unbalance of the workpiece. Mass of workpiece has little effect on the signal. Calibration can be well defined.

    The the marking pen (IMHO) is the way to begin. Marking pen only works for low tune system.
    I do car tail shafts on the vehicle with a piece of chalk ! It is that easy.
    and the worm drive hose clips just get left there as the correction.

    I have balanced shafts like this up to 8000 RPM
    The faster it goes, the longer the stick with the chalk held on the end. SAFETY FIRST!

    I will watch this space...
    Super X3. 3600rpm. Sheridan 6"x24" Lathe + more. Three ways to fix things: The right way, the other way, and maybe your way, which is possibly a faster wrong way.

  7. #7
    Join Date
    Jul 2008
    Posts
    17
    Hi Turbinecrazy,

    I see you located in SA - so am I whereabout are you? I am buliding a smaller version of a KJ66 turbine and would like to know if you have built/are building something similar?

  8. #8
    Join Date
    Dec 2004
    Posts
    13
    I see this guy made a balancer just for what you are wanting to do. I hope this might be of some help.

    http://www.technologie-entwicklung.d...cing_tool.html

  9. #9
    Join Date
    Oct 2006
    Posts
    7
    hi there thanks for the info....

    Yep i am busy building a KJ66 for a university project....i am from cape town South Africa.....

  10. #10
    Join Date
    Jul 2008
    Posts
    17
    Hi TC,

    Just wana know how far are you with the project? Have you made the NGV and Turbine yet?

  11. #11
    Join Date
    Oct 2006
    Posts
    7
    nope was concentrating on my balancing of my shaft.......but that should easy to do....so thats the least of my worries.....

  12. #12
    Join Date
    Nov 2008
    Posts
    19
    For a dynamic balancer specially designed for micro turbines try to contact
    [email protected] and he will help you for sure.
    I have one of his balancers and managed to balance a wren 54 shaft to less than 5mg on turbine wheel and compressor.

  13. #13
    Join Date
    Jan 2008
    Posts
    60
    I didn't think it was this simple. I hear quotes for 400 dollars to balance turbos but from the looks of this project I might try making my own. I usually just put a scribe on the nut and the compressor wheel and just cross my fingers and try to line it up.
    Wish that guy threw up some dimensions but the electronics are probably what I'd have more trouble with than anything, at least he put up a schematic.

    Edit: Insert Foot A into Mouth B. I found the drawings on the very next link I clicked.


    --Steve

  14. #14
    Join Date
    Nov 2007
    Posts
    45
    Quote Originally Posted by fz1 View Post
    I see this guy made a balancer just for what you are wanting to do. I hope this might be of some help.

    http://www.technologie-entwicklung.d...cing_tool.html
    old thread but just in case someone is looking for those parts on that site. I have cnc machined 2 sets a long time ago so if anyone is in CT and interested just pm me, u can have them for free just come & collect.

  15. #15
    Join Date
    Jan 2008
    Posts
    60
    What a coincidence! I am in CT!
    We are talking Connecticut, right? I see your location in your details reads South Africa.


    --Steve

  16. #16
    Join Date
    Nov 2007
    Posts
    45
    Quote Originally Posted by Paraquat View Post
    What a coincidence! I am in CT!
    We are talking Connecticut, right? I see your location in your details reads South Africa.


    --Steve
    Hi Steve

    sorry no - I live in Cape Town (CT) South Africa.

    regards
    anilam

  17. #17
    Join Date
    Apr 2006
    Posts
    3498
    Hi very interesting thread
    I am still in search of DIY solution to balancing.. But i will go with the Keyphasor and proximity tranducers way... If their is any body who can tell me what type of electronics following guys are using?
    www.precibalance.com/
    http://www.balancemaster.com/

    Regards
    http://free3dscans.blogspot.com/ http://my-woodcarving.blogspot.com/
    http://my-diysolarwind.blogspot.com/

  18. #18
    Join Date
    Apr 2006
    Posts
    3498
    Hi Neil,
    I am really impressed to know you are expert in balancing.. Can you guide me making a 2-plane balancing machine... Actually we have CEMB Model WA-3000 that we want to convert into Digital balancing..
    Is it possible we can make a DIY arrangement?
    http://free3dscans.blogspot.com/ http://my-woodcarving.blogspot.com/
    http://my-diysolarwind.blogspot.com/

  19. #19
    Join Date
    Jun 2007
    Posts
    3757

    Just get back to basics.

    Understand the principals.

    http://en.wikipedia.org/wiki/Balancing_machine

    The tricky part is is learning how to process low frequency signals with precision, and interpreting them.
    As for the balancing planes, it is a just like balancing CW and CCW moments on a beam, around the planes where the pickups are.
    You add the correct proportions of each signal, with each other to resolve plane(s) inside and/or outside the pickups, but all done with AC signals, just to make life a little more difficult.

    If you already have a machine, you are already a long way to making a digital machine. A PC is more than powerful enough, in real time to get excellent results, but this is not a trivial exercise. Search the web....

    Digitally there are quite a few techniques, and on the web you will find most of them.

    As for me, I wish I had the time to do some balancing programming, but that's another year. This one and the next is full.

    Neil
    Super X3. 3600rpm. Sheridan 6"x24" Lathe + more. Three ways to fix things: The right way, the other way, and maybe your way, which is possibly a faster wrong way.

  20. #20
    Join Date
    Apr 2006
    Posts
    3498
    Hi Neil,
    Last year i have attended the course on "Machinery Diagnostics" conducted by GE energy at Florence. The practice session was carried out on SYSTEM1 of Bentley. I have studied a lot about vibration and balancing ... Single plane, Two planes and Multiple planes balancing----

    But the Bentley system is tremendously expensive, because it do much more than balancing ...

    So just came through BalanceMaster and saw their simple hardware and software specific to balancing... and... It really attracted me..but again the cost is high not for us the hobbiest

    Currently, for my own, i want to make a DIY simple system for balancing..This is to get more experience at my home..a kind of R &D..

    I have seen some applications that can get PHASE as well as 1X vibration using SOUND-CARD.. You can google "Virtual Oscilloscope using Sound-card" and you will find some free applications.

    Programming is not difficult for me... but i need to see some DIY stuff on balancing to make the reliable BASE
    http://free3dscans.blogspot.com/ http://my-woodcarving.blogspot.com/
    http://my-diysolarwind.blogspot.com/

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