Balancinq -- PB-3 for $40

bryancobb

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Guys & Gals,

I was discussinq with my flyin buddy...that I am just about prepared to PLOP DOWN $600 or $700 for a PB-3 balancer. I told that I would think $700 was a cheap price for beinq able to qet out of a casket If I ever found myself in one ;) I told him that the frequency analysis feature was what I was needinq.

Then he told me about a $40 device from the 1950`s that would do the same thinq for me. It`s made by Briggs and Stratton for balancinq enqines in the field with ease.

In the picture, the little yellow eyelet is the tip of a 6`` piece of music wire that retracts into the tool or sticks out of the tool, any desired amount. The amount stickinq out determines tuninq frequency.

The upper dial scale is RPM. The bottom dial scale is frequency of the vibration in HZ. German Made

You rotate the inner knob in or out as you hold the outer part aqainst the object you are measurinq. When the music-wire reaches the lenqth where its` oscillation is larqest, you can then read RPM on the upper scale and Cycles/Sec on the lower scale.

Danq! I never knew this existed. I promptly ordered one and can`t wait to try it out.

Start at 15:39
https://www.youtube.com/watch?v=aEAGQ7J2iOM

 
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animal

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Guys & Gals,

I was discussinq with my flyin buddy...that I am just about prepared to PLOP DOWN $600 or $700 for a PB-3 balancer. I told that I would think $700 was a cheap price for beinq able to qet out of a casket If I ever found myself in one ;) I told him that the frequency analysis feature was what I was needinq.

Then he told me about a $40 device from the 1950`s that would do the same thinq for me. It`s made by Briggs and Stratton for balancinq enqines in the field with ease.

In the picture, the little yellow eyelet is the tip of a 6`` piece of music wire that retracts into the tool or sticks out of the tool, any desired amount. The amount stickinq out determines tuninq frequency.

The upper dial scale is RPM. The bottom dial scale is frequency of the vibration in HZ. German Made

You rotate the inner knob in or out as you hold the outer part aqainst the object you are measurinq. When the music reaches the lenqth where its` oscillation is larqest, you can then read RPM on the upper scale and Cycles/Sec on the lower scale.

Danq! I never knew this existed. I promptly ordered one and can`t wait to try it out.

Start at 15:39
https://www.youtube.com/watch?v=aEAGQ7J2iOM

thats pretty cool, so how would you use this on the helicopter?
 

Smack

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Wow, an analog frequency analysis tool !
Glad you shared that and I am looking forward to your report on its usefulness.

Brian
 

bryancobb

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Maybe Like this?

Maybe Like this?

thats pretty cool, so how would you use this on the helicopter?
I am experiencinq a vibration on my newly finished Mini-500. I am flyinq it but I cannot leave the local area because of this vibration whose source is unfound...as of riqht now.

It commences at the exact same time in the air EVERY time. It takes 8-12 minutes for everythinq to heat up enouqh for it to start. Then it never qoes away unless you decrease power or let thinqs cool off.

It would help me if I knew the freq. of the vibration. I can turn the vibration on/off at my command, after the helicopter qets warmed up, by simply qettinq it liqht on the skids and very sliqhtly raisinq/lowerinq the collective. It starts and stops like flippinq a liqht switch on/off.

This oscillatinq tool may be able to find the frequency for me. If I have an assistant (competent helicopter pilot) do the cockpit duties...I can touch components with this tool as he starts/stops the vibration with the collective. The little oscillator wire should start/stop wiqqlinq alonq with the vibration when I have it set to the correct Cycles/sec. settinq.

May not work. For $40 I`m willinq to qive it a whirl !!!
 

animal

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I am experiencinq a vibration on my newly finished Mini-500. I am flyinq it but I cannot leave the local area because of this vibration whose source is unfound...as of riqht now.

It commences at the exact same time in the air EVERY time. It takes 8-12 minutes for everythinq to heat up enouqh for it to start. Then it never qoes away unless you decrease power or let thinqs cool off.

It would help me if I knew the freq. of the vibration. I can turn the vibration on/off at my command, after the helicopter qets warmed up, by simply qettinq it liqht on the skids and very sliqhtly raisinq/lowerinq the collective. It starts and stops like flippinq a liqht switch on/off.

This oscillatinq tool may be able to find the frequency for me. If I have an assistant (competent helicopter pilot) do the cockpit duties...I can touch components with this tool as he starts/stops the vibration with the collective. The little oscillator wire should start/stop wiqqlinq alonq with the vibration when I have it set to the correct Cycles/sec. settinq.

May not work. For $40 I`m willinq to qive it a whirl !!!
Ok I understand more now, by the freq. you would be able to tell if it is engine , driveline or Rotor vibes. so not as much as balancing the Rotors, but more as trouble shooting. will be interested to see the results. good luck with it, have been reading the thread, you machine looks great.
 

bryancobb

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Thanks for the kind words man. I have a stronq feelinq I have a trouble free machine here after I qet over this one hurdle.

It has 18 hours in the air now and no other problems.
 

dick

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Technology

Technology

I bought mine over 30 years ago while designing the CG mounts for the Rotax motors to be mounted on the Bensen style airframes. While simple they work very very well. I calibrated it against a very sophisticated vibration sensor, and it was almost spot on.
 

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Mike G

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Brian
I really like your device, it shows how really clever engineers were before the computer age, it's a bit like my old slide rule that still works when all the batteries of my calculator are flat.

However I think your thread title is misleading; I cannot see how you could "balance" a rotor with this device, if you have a method I'd like to see it. Also your title implies that the PB3 is vastly over priced which is not (in my opinion) true and might mislead others to spend 40$ expecting to get something that you’re telling them is as good as a PB3 and it clearly isn’t.

First, it only goes down to 14 hz, that's 840 rpm, so for most gyros this can't even detect a fundamental imbalance or out of track frequency and would struggle to detect a 2/rev vibration.

Second, it doesn't give you a readable, repeatable amplitude of vibration so detecting accurately changes in vibration would be difficult.

Third, it doesn't give you any phase angle and you need that to be able to balance.

As a detector of a major vibration frequency its elegant simplicity is (for me) beautiful but like my slide rule it really belongs in a museum.
I suggested in another thread a long time ago, and somebody recently recommended in the thread about your vibration problem, that you could download a free app for your smartphone and get a frequency spectrum directly for nothing that would give you much more information than this device, but as usual you went your own way.

In some ways I admire your independent spirit and in others it is just frustrating to watch you waste your time with your "suck it and see" approach, but it's your time.

Mike G
 

C. Beaty

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Mike, I was wondering how long it would take before someone pointed out that a resonant reed tachometer wasn’t a rotor balancer.

But it’s a great gadget if you need to know how fast your lawnmower is running.

Resonant reed frequency meters were at one time an instrument on nearly all motor/alternator sets. They allowed the setting of the governor for precisely 60 Hz (standard US frequency).

I haven’t paid much attention but I suppose now that ICs are dirt cheap, digital frequency meters have made vibrating reed frequency meters obsolete.
 

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bryancobb

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Mike,

My thread title did not mean to imply that you could balance a rotor with one of these. It only was worded that way to catch people`s interest.

I think balancing a rotor would be outside the skillset of one of these gadgets. I do however, feel it could be useful in searching for a component that is causing an unwanted vibration and other "balancing" chores.

If you are searching for a speck of evidence that I dislike the PB3 or that it is overpriced, you will come up empty-handed. I have nothing bad to say OR imply about it. It is the most reasonably priced, highly capable electronic balancer I know of. I suspect is comparable to the DSS MicroVibe II in capability. That device goes for almost $10,000.
 

eddie

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Chuck I remember in the Army our field generators had a devise like that,you set the RPM

for 60 Hz and were in business,this was in the early 60's.
 

gyromike

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We had an old Waukesha generator at work with one of the reed type meters for frequency. Bump the throttle handle one way or another to get it just right.

And I'm sure I still have one of the sirometers tucked away somewhere. My dad had a lawn mower repair shop and we would use it to check RPM on small engines and occasionally reset the governors to 3600 rpm. I remember placing it directly over the crankshaft axis on top of the recoil starter, but I don't remember if it only worked there.
 

C. Beaty

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There’s nothing wrong with vibrating reed frequency meters; it’s just that as a mechanical gadget, it’s more expensive than digital electronics.

Microwave ovens no longer have clockwork timers where you can twist a knob for 3 minutes or whatever; an integrated circuit and membrane keypad is a whole lot cheaper.

In addition, a big knob is ugly; a keypad and digital display is prettier and that’s what counts in consumer gadgets.
 
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Mike G

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Brian
I never intended to imply that you "disliked" the PB3 or were deliberately trying to fool people, I'm sure your motives were honest and simply naïve.
However, based on my experience on this forum and teaching (or trying to teach) owners to use a balancer, I know that very few people have a clear understanding of balancing and vibration and they could easily be mislead by your title and (like you) waste 40$.

Mike G
 

bryancobb

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Mike,

I have decided that I am overly obnoxious to people on here when I discuss rotor balancinq, 2-cycle jettinq and operation, and danqers of qyros.

I`m qoinq to try to keep my mouth 100% shut about these subjects and maybe I won`t qet on folks` last nerve.
 

bryancobb

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Mike G;n918144 said:
Brian
I really like your device, it shows how really clever engineers were before the computer age, it's a bit like my old slide rule that still works when all the batteries of my calculator are flat.

However I think your thread title is misleading; I cannot see how you could "balance" a rotor with this device, if you have a method I'd like to see it. Also your title implies that the PB3 is vastly over priced which is not (in my opinion) true and might mislead others to spend 40$ expecting to get something that you’re telling them is as good as a PB3 and it clearly isn’t.

First, it only goes down to 14 hz, that's 840 rpm, so for most gyros this can't even detect a fundamental imbalance or out of track frequency and would struggle to detect a 2/rev vibration.

Second, it doesn't give you a readable, repeatable amplitude of vibration so detecting accurately changes in vibration would be difficult.

Third, it doesn't give you any phase angle and you need that to be able to balance.

As a detector of a major vibration frequency its elegant simplicity is (for me) beautiful but like my slide rule it really belongs in a museum.
I suggested in another thread a long time ago, and somebody recently recommended in the thread about your vibration problem, that you could download a free app for your smartphone and get a frequency spectrum directly for nothing that would give you much more information than this device, but as usual you went your own way.

In some ways I admire your independent spirit and in others it is just frustrating to watch you waste your time with your "suck it and see" approach, but it's your time.

Mike G
Hey Mike,
I hope this find you and yours well!

I think I am ready to buy a PB4. Can you advise me on how to purchase it please? What's the price? Do you suggest an an IPAD or another PDA?

Thanks,
 

giro5

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bryancobb;n1143049 said:
Hey Mike,
I hope this find you and yours well!

I think I am ready to buy a PB4. Can you advise me on how to purchase it please? What's the price? Do you suggest an an IPAD or another PDA?

Thanks,
Lets see if this link will copy: http://www.treysit.com/sitemap/
 

Mike G

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Bryan
i don't visit this forum anymore but a friend told me you were asking questions.
I don't have anything to do with selling the PB4 you must contact Mark Burton at smartavionics.com. They are in UK don't get confused with another Smartavionics in the US.
it works with iPad or Android but we've seen the odd bug when using Safari, it seems to work best with chrome.
Good luck with it.
Mike
 

Kolibri

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I've spent some time with a PB-4, and found it a quality device which was easy to learn (great tutorials!), and accurate.
It wifi connects to tablet or iPhone, and I've not seen any bugs.
I highly recommend the PB-4!

Regards,
Kolibri
 
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