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rickpegser(at)yahoo.com
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 Posted: Thu May 28, 2009 7:06 pm Post subject: DynaVibe prop Balancer |
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gentelman:
i use an ird smart meter 720. it gives me phase angle and amplitude of the vibration. second to this i use a ti 89 programed to give me the weights and angles i need for balancing. i have two channels front and back , i find that i only do the front unless i find a problem with the engine or mount. i have been told the the local experts that i need to play with the prop weights. as an i/a without a propshop repair station endorment i have to follow the rule for balancing and that limits me to the spinner backing plate. if any one is playing with the prop wieghts you should run.
there is several problems with the cheap gear.
1 most of them do not do full spectrium anlysis.
2 you are unable to get the harmonics from the cheap gear.
3 some of them don't do phase angle, whlie you can still balance without phase angle it takes atleast 4 runs.
the next question is why?
the average cost for a balance is about 250.00$ this ballance will last untill a prop change/ engine change.
so you have a choice buy a questionable piece of equipment. and try to do the job yourself. or hire someone with the right gear to do the job right, for 1/8 the cost of trying to buy the trash gear.
rick i/a a+p
--- On Wed, 4/22/09, Ralph Finch <rgf(at)dcn.davis.ca.us> wrote:
[quote] From: Ralph Finch <rgf(at)dcn.davis.ca.us>
Subject: RE: DynaVibe prop Balancer
To: rv-list(at)matronics.com
Date: Wednesday, April 22, 2009, 10:18 AM
"Ralph Finch" <rgf(at)dcn.davis.ca.us>
A typical dynamic balancer will place an accelerometer on
the engine and a
small reflective timing tape on the prop along with a cheap
light detector.
The outputs are sent to the balancer which using equations
of vibration will
figure out where and how much weight to place on the
spinner backplate. No
strobe involved, and certainly no trial and error: it's all
deterministic.
Once the weight is placed, it's measured once again to
check the improvement
and job done.
Our RV club a year ago had a great presentation by a fellow
who measures the
acceleration (vibration) both fore and aft, not just in the
front.
Apparently this does a better job.
The principles of dynamic balancing are not quantum
chromodynamics and the
equipment should be inexpensive, so no reason why these
things should cost
huge amounts.
RF
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rickpegser(at)yahoo.com
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| Posted: Fri May 29, 2009 3:26 am Post subject: DynaVibe prop Balancer |
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the dyna vibe does not give you full spectrum, and has questionable averaging. one problem is that it does not use a laser for the tach/phase angle pickup. it there for requires that you tape the pickup to the cowl instead of the wing. if the pickup breaks loose it will trash your canopy.
the problem with group vibration gear is that accelerometers are like spark plugs you only get to drop them twice, once on the floor and once in the trash can.
but lets assume i was using a dynavibe, it will give you a magitude and phase angle. the next problem it that for test runs i will be adding weight to the spinner retianing screws. after i balance a prop that way i have to move the weight to the spinner backing ring, this requires a little math that most owners don't have.
the biggest problem with balancing is most people do not understand the math behind it.
i can balance a prop with a piece of safety wire, a fishing weight, and a ruler. it takes me about 12 runs to do it that way, but it impresses the kids. with phase angle input i can do it in four runs, without call it 8 runs.
so to answer the question, will the dynavibe work. yes
will it tell you if the mount is the problem, or the balancer, NO.
can you walk out to any aircraft and balance it after buying it. no
will it take training to determine the the problem, yes
so go flying and leave the balancing to the pros, if you don't have a pro in the area, call me i will find you one.
rick a+p,i/a
--- On Wed, 4/22/09, Robin Marks <robin1(at)mrmoisture.com> wrote:
| Quote: | From: Robin Marks <robin1(at)mrmoisture.com>
Subject: RE: DynaVibe prop Balancer
To: rv-list(at)matronics.com
Date: Wednesday, April 22, 2009, 12:52 AM
Zero
experience with the device but my local prop shop charges
$200 and says he should
probably charge more. Should not take long to pay for
it.
Robin
Do
Not Archive
From:
owner-rv-list-server(at)matronics.com
[mailto:owner-rv-list-server(at)matronics.com] On
Behalf Of Bill Judge
Sent: Tuesday, April 21, 2009 5:05 PM
To: rv-list(at)matronics.com
Subject: DynaVibe prop Balancer
Fellow
RV drivers:
does anyone have any first hand experience with the
DynaVibe dynamic prop
balancing test set?
http://www.rpxtech.com/rpxweb/Dynavibe.asp
They are $1500 I'm kicking around the idea of throwing
in with some other
experimental owners and getting one. I've had
some trouble getting my
prop balanced locally and for $1500 it wouldn't take to
many interested parties
in my EAA Chapter to justify it. I just need to know
that it does the
job.
Thanks
Bill
N84WJ
http://www.matronics.com/Navigator?RV-Listhttp://forums.matronics.comhttp://www.matronics.com/contribution
No virus
found in this incoming message.
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04/21/09
16:48:00
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