 |
Matronics Email Lists
Web Forum Interface to the Matronics Email Lists
|
| View previous topic :: View next topic |
| Author |
Message |
JohnF
Joined: 13 May 2010
Posts: 124
|
 Posted: Fri Jan 24, 2014 8:49 pm Post subject: Dyna Vibe Prop Dynamic Balancer Question |
 |
|
Maybe Roger Lee can answer this one:
I purchased a Dyna Vibe dynamic prop balancer and the instructions seem clear except for this statement:
"If the accelerometer cable is pointing away from the center of the bub, then the angle reported by the Dyna Vibe is the HEAVY spot (where to remove weight, or 180 degrees from where to add weight.) If you flip it so the accelerometer cable is pointing toward the hub, then the reading will indicate the light spot (where to ADD weight.)"
Question: How can be orientation of the cable (not the accelerometer) change what the reading angle means? (ie, heavy or light)
| | - The Matronics RotaxEngines-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?RotaxEngines-List |
|
|
|
| Back to top |
|
 |
Roger Lee
Joined: 10 Jan 2006
Posts: 1464
Location: Tucson, Az.
|
| Posted: Sat Jan 25, 2014 4:47 am Post subject: Re: Dyna Vibe Prop Dynamic Balancer Question |
|
|
Hi John,
Sorry I'm out of the info loop on this one. I don't have a clue.
| | - The Matronics RotaxEngines-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?RotaxEngines-List |
|
_________________
Roger Lee
Tucson, Az.
Rotax Instructor & Rotax IRC
Light Sport Repairman
Home 520-574-1080 TRY HOME FIRST
Cell 520-349-7056 |
|
| Back to top |
|
|
BARRY CHECK 6
Joined: 15 Mar 2011
Posts: 738
|
| Posted: Sat Jan 25, 2014 5:22 am Post subject: Dyna Vibe Prop Dynamic Balancer Question |
|
|
John:
I missed the question... I have a Dyna Vibe, how can I help?
Barry
On Sat, Jan 25, 2014 at 7:47 AM, Roger Lee <ssadiver1(at)yahoo.com (ssadiver1(at)yahoo.com)> wrote:
[quote] --> RotaxEngines-List message posted by: "Roger Lee" <ssadiver1(at)yahoo.com (ssadiver1(at)yahoo.com)>
Hi John,
Sorry I'm out of the info loop on this one. I don't have a clue.
--------
Roger Lee
Tucson, Az.
Light Sport Repairman - Maintenance Rated
Rotax Repair Center - Heavy Maint. Rated
Home [url=tel:520-574-1080]520-574-1080[/url] TRY HOME FIRST
Cell [url=tel:520-349-7056]520-349-7056[/url]
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=417561#417561
===========
-List" target="_blank">http://www.matronics.com/Navigator?RotaxEngines-List
===========
http://forums.matronics.com
===========
le, List Admin.
="_blank">http://www.matronics.com/contribution
===========
[b]
| | - The Matronics RotaxEngines-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?RotaxEngines-List |
|
|
|
| Back to top |
|
|
BARRY CHECK 6
Joined: 15 Mar 2011
Posts: 738
|
| Posted: Sat Jan 25, 2014 5:42 am Post subject: Dyna Vibe Prop Dynamic Balancer Question |
|
|
Hi John:
I just read the original post.
The answer is: It Can't!
It has to be a misprint.
I'm thinking it is easier to describe the accelerometer by identifying the cable as apposed to the mounting threads. Which will be hidden when mounted.
Can you tell me what page that statement is on? And also what revision of the manual you are reading?
If you really wanted to attempt something crazy, YES, you could make a mount that points the accelerometer way from the HUB (Center of the shaft). And that would give you the Lite Point, but, you would probably be adding all sorts of erroneous vibrations due to the extended size of the bracket. I do not understand why Dyna Vibe did not simply have the feature of REVERSING the math or the output of the accelerometer. Or why they used such a large housing for the accelerometer; phones and iPads have surface mount accelerometers that are only 0.100" high and 0.250" square. Take that and pot it and you are done. Oh, well! It works.
Barry
On Fri, Jan 24, 2014 at 11:49 PM, JohnF <n29cx(at)ridgeviewtel.us (n29cx(at)ridgeviewtel.us)> wrote:
[quote]--> RotaxEngines-List message posted by: "JohnF" <n29cx(at)ridgeviewtel.us (n29cx(at)ridgeviewtel.us)>
Maybe Roger Lee can answer this one:
I purchased a Dyna Vibe dynamic prop balancer and the instructions seem clear except for this statement:
"If the accelerometer cable is pointing away from the center of the bub, then the angle reported by the Dyna Vibe is the HEAVY spot (where to remove weight, or 180 degrees from where to add weight.) If you flip it so the accelerometer cable is pointing toward the hub, then the reading will indicate the light spot (where to ADD weight.)"
Question: How can be orientation of the cable (not the accelerometer) change what the reading angle means? (ie, heavy or light)
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=417551#417551
===========
-List" target="_blank">http://www.matronics.com/Navigator?RotaxEngines-List
===========
http://forums.matronics.com
===========
le, List Admin.
="_blank">http://www.matronics.com/contribution
===========
[b]
| | - The Matronics RotaxEngines-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?RotaxEngines-List |
|
|
|
| Back to top |
|
|
JohnF
Joined: 13 May 2010
Posts: 124
|
| Posted: Sat Jan 25, 2014 7:30 am Post subject: Dyna Vibe Prop Dynamic Balancer Question |
|
|
Barry, thank you for the response. The statement is on page 33 of the manual, second paragraph from the bottom. I have version 1-07. I am repeating below the answer I got from Dyna Vibe which I will have to read and re-read several times to try to understand it..
One other question I have is just exactly what is the 'axis of the accelerometer' - is the vertical orientation of the unit, or some rotational position? I don't have a clue.
Anyway, here is the answer from RPX...maybe you can help me clarify what they are telliing me.
Fun question.<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" />
It has to do with the timing of the signals and what the accelerometer “feels” vs when it feels it with respect to the optical tach signal. If the accelerometer is rotated 180 degrees then the signals are backwards. That’s why the solution flips (heavy vs light). If you are 90 degrees, then you will sense engine rotation in addition to vibration but the vibration will be rotated 90 degrees and mixed with rotational vibration. So that’s not really useful. If you are at 45 degrees, then you will sense rotation and vibration, but at a complex angle. So the math would be quite convolved. You would have to separate rotation, x vibration, and y vibration, which can’t be done without more sensors to see what is going on.
But I don’t think you are looking for the literal answer to your question. So the actual answer is that you want the axis of the accelerometer pointing toward the center of rotation. If it isn’t, then you start sensing rotational vibration which isn’t what you are looking for. And if the sensor is backwards, then the math in the meter will be backwards. Which explains the heavy vs light statement
Thanks again for your ehlp.
John
[quote] ---
| | - The Matronics RotaxEngines-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?RotaxEngines-List |
|
|
|
| Back to top |
|
|
BARRY CHECK 6
Joined: 15 Mar 2011
Posts: 738
|
| Posted: Sat Jan 25, 2014 9:08 am Post subject: Dyna Vibe Prop Dynamic Balancer Question |
|
|
John:
The answer can be quite confusing. Why? Because I'm an engineer and there
are no simple answers 
Ok, the short version:
There are Three (3) primary axis's: X - Y - Z
X - is the Horizontal axis from Left to Right.
Y - Is the Vertical axis and is perpendicular to the X axis consider the
letter L
Z - is ... Harder to explain, take the letter L and draw a line from the
point where the Vertical and Horizontal come together BUT - Draw it
straight out towards you.
Now, 'axis of the accelerometer'. That is the way it is mounted... It
should be Vertical - Straight Up and Down. AND mounted ON TOP of the engine
- - - What Dyna Vibe is also explaining is the relationship between the
Accelerometer and the Photo Eye for obtaining the RPM. ALL your reading
will be in reference to the photo eye and what you deem the #1 blade of the
prop. The degree position of rotation is in relationship to the photo eye.
SO... If the Accelerometer is mounted on the Center-Line (C/L) of the
engine and the photo eye is off to one side (as in the pictures in the
manual) the degree indication of the Heavy point will NOT align with the
Accelerometer. AND THIS will drive you crazy when you try to put the
balance weights on. Example: The Dyna Vibe will say the heavy point is 090
Deg... You add 180 Deg and get 270 Deg... BUT! The photo eye is OFF C/L
to the right (facing) by say 1"... That will ADD about 15 Deg to the 270
reading and give you 285 Deg for the lite point. If you do
not consider this little fact you will chasing your tail trying to find the
prop balance point.
How do you correct this error? Make a bracket that puts the Accelerometer
and Photo Eye on the same Vertical Y axis.
I should sell these brackets but the price would be too high...
I read the response from Dyna Vibe... Yea, I understand it but it is
not very clear. They could have done a better job. Go with my
above explanation and things will work out correctly.
Now, my question: What plane and engine are you trying to balance?
I want to balance a friends Rotax Pusher but there is NO ring
gear/flywheel, where can I put the weights? It is also a three (3) blade
prop. <-- That makes no difference - Can do!
Barry
On Sat, Jan 25, 2014 at 10:30 AM, JohnF <n29cx(at)ridgeviewtel.us> wrote:
[quote] Barry, thank you for the response. The statement is on page 33 of the
manual, second paragraph from the bottom. I have version 1-07. I am
repeating below the answer I got from Dyna Vibe which I will have to read
and re-read several times to try to understand it..
One other question I have is just exactly what is the 'axis of the
accelerometer' - is the vertical orientation of the unit, or some
rotational position? I don't have a clue.
Anyway, here is the answer from RPX...maybe you can help me clarify what
they are telliing me.
Fun question.
It has to do with the timing of the signals and what the accelerometer
“feels” vs when it feels it with respect to the optical tach signal. If the
accelerometer is rotated 180 degrees then the signals are backwards. That’s
why the solution flips (heavy vs light). If you are 90 degrees, then you
will sense engine rotation in addition to vibration but the vibration will
be rotated 90 degrees and mixed with rotational vibration. So that’s not
really useful. If you are at 45 degrees, then you will sense rotation and
vibration, but at a complex angle. So the math would be quite convolved.
You would have to separate rotation, x vibration, and y vibration, which
can’t be done without more sensors to see what is going on.
But I don’t think you are looking for the literal answer to your
question. So the actual answer is that you want the axis of the
accelerometer pointing toward the center of rotation. If it isn’t, then you
start sensing rotational vibration which isn’t what you are looking for
| | - The Matronics RotaxEngines-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?RotaxEngines-List |
|
|
|
| Back to top |
|
|
BARRY CHECK 6
Joined: 15 Mar 2011
Posts: 738
|
| Posted: Sat Jan 25, 2014 10:11 am Post subject: Dyna Vibe Prop Dynamic Balancer Question |
|
|
Right you are John!
"I agree that RXP could improve their manual.....its hard to write clearly
when you have total knowledge of the subject and are writing to someone
else that isn't on board yet. You can easily forget to be detailed enough
to satisfy the uninformed mind.
Cheers
John"
John:
I wrote many a procedure and manual and you have to write as if the person
reading is not in the room with you and had no knowledge of the subject. I
use to say many a tech writer cannot see the forest, for the trees. Just
look at Micro Soft... The information they supplied was totally accurate,
but totally useless.
Barry
On Sat, Jan 25, 2014 at 10:30 AM, JohnF <n29cx(at)ridgeviewtel.us> wrote:
[quote] Barry, thank you for the response. The statement is on page 33 of the
manual, second paragraph from the bottom. I have version 1-07. I am
repeating below the answer I got from Dyna Vibe which I will have to read
and re-read several times to try to understand it..
One other question I have is just exactly what is the 'axis of the
accelerometer' - is the vertical orientation of the unit, or some
rotational position? I don't have a clue.
Anyway, here is the answer from RPX...maybe you can help me clarify what
they are telliing me.
Fun question.
It has to do with the timing of the signals and what the accelerometer
“feels” vs when it feels it with respect to the optical tach signal. If the
accelerometer is rotated 180 degrees then the signals are backwards. That’s
why the solution flips (heavy vs light). If you are 90 degrees, then you
will sense engine rotation in addition to vibration but the vibration will
be rotated 90 degrees and mixed with rotational vibration. So that’s not
really useful. If you are at 45 degrees, then you will sense rotation and
vibration, but at a complex angle. So the math would be quite convolved.
You would have to separate rotation, x vibration, and y vibration, which
can’t be done without more sensors to see what is going on.
But I don’t think you are looking for the literal answer to your
question. So the actual answer is that you want the axis of the
accelerometer pointing toward the center of rotation. If it isn’t, then you
start sensing rotational vibration which isn’t what you are looking for
| | - The Matronics RotaxEngines-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?RotaxEngines-List |
|
|
|
| Back to top |
|
|
|
|
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum
|
Powered by phpBB © 2001, 2005 phpBB Group
|
Get Email Distribution Too!
FAQ
Search
Memberlist
Usergroups
Register
Profile
Log in to check your private messages
Log in
