Go Back  RCU Forums > RC Airplanes > Beginners
Reload this Page >

prop balancing

Notices
Beginners Beginners in RC start here for help.

prop balancing

Old 06-03-2008, 06:24 PM
  #1  
F-18
Member
Thread Starter
 
Join Date: Jan 2006
Location: East Kootnay, BC, CANADA
Posts: 87
Likes: 0
Received 0 Likes on 0 Posts
Default prop balancing

I was going to order some new props for my alpha 60 when i saw an add for a prop balancer. i want to know how important it is ti balance a prop for a trainer and if i should invest in the balancer. thanks
Old 06-03-2008, 06:29 PM
  #2  
Jetdesign
My Feedback: (8)
 
Jetdesign's Avatar
 
Join Date: May 2008
Location: Honolulu, HI
Posts: 7,056
Received 0 Likes on 0 Posts
Default RE: prop balancing

It is important, and yes, you should invest in one. There are the finger tip balancers, too, which do an ok job (that's what I use 'cause I'm broke).

Balancing a prop saves tons of engine and structure wear by decreasing vibrations. People will say that props come pretty close to being balanced; I have yet to see one - every prop I've come across needed something (little sanding or addition of some clear acrylic).

Engines are expensive, balancers are not. They are a good investment.
Old 06-03-2008, 06:47 PM
  #3  
Flying freak
Senior Member
 
Join Date: Jun 2006
Location: granby, QC, CANADA
Posts: 1,407
Likes: 0
Received 0 Likes on 0 Posts
Default RE: prop balancing

I dont balnce the ones going on my trainer its a simple 2 stroke thats low rpm But it is a good idea i do it for all race engines big engines and 4 strokes...

on the other hand i once forgot to balance a prop for a jett 50 and within about 2 minutes the vibration had broke 3 of the 4 8-32 cap head bolts [X(]

I personally dont like the fingure tip balancers your almsot better not to balance there so on accurate... you could ahve one horribly out of balance and and not know with those thigns...


Steven
Old 06-03-2008, 06:54 PM
  #4  
RCKen
RCU Forum Manager/Admin
My Feedback: (9)
 
RCKen's Avatar
 
Join Date: Jul 2002
Location: Lawton, OK
Posts: 27,759
Likes: 0
Received 27 Likes on 24 Posts
Default RE: prop balancing

This is a subject that comes up quite a bit here, and it always turns into a huge discussion. I'm not going to say that people are wrong for balancing their props, if they want to do that then by all means I encourage them to do it. But in my experience it's really a waste of time. Minnflyer and I have had long discussions about this and we both say the same thing. I check a prop when I first get it, and as long as it's not GROSSLY out of balance it gets used as is. If it is WAY out of balance then I simply toss it, or return it to where I bought it if possible. So why don't I balance?? I used to do it. I wound spend great time and effort to make sure that the prop was just "perfect" and would sit there perfectly level on the prop balancer. Then I would put it on the plane and the first trip to the field a prop strike, a rock hitting the prop, and even the green from running it through grass can throw them out of balance. What I'm trying to say is that they get out of that perfect balance pretty quickly. So I pretty much gave up, I have better things to do with my time than balance props. And I have engines that have hundreds of flights on them that haven't been damaged from running an unbalanced prop. In fact, my GP Slow Poke has over 500 flights on it and it's still got the same prop that it started with. It's been dinged and nicked many times but then engine, prop, and plane are still going strong.

Now I'm not saying that everybody needs to not worry about balancing. There are some that compete that NEED to balance to be competitive, as well as others that need to do it. But for those of us that are just "sport flyers" it's not worth the effort for minimal gains. I equate it to an Indy Racer. They will spend millions of dollars to can fractions of seconds in time, and it's worth it to them to be competitive. But for the rest of us that drive to work every day that kind of money and effort would be totally wasted.

And as I said, I'm not arguing with those that do balance their props. And I'm not saying they are wrong. I've been in the hobby long enough and seen this discussion often enough to know that I would be silly for saying that. I am simply passing on what I do and my reasons for it.

Hope this helps.

Ken
Old 06-03-2008, 06:59 PM
  #5  
Insanemoondoggie
 
Insanemoondoggie's Avatar
 
Join Date: Nov 2006
Location: Altamont, MO
Posts: 2,475
Received 1 Like on 1 Post
Default RE: prop balancing

Any good mechanic well tell you ,if it`s a rotating assembly , it needs to be balanced . Some will tell you no and argue till the sun goes down , that it dont matter . But anything turning 10,000 plus rpms needs to be checked.
Old 06-03-2008, 07:15 PM
  #6  
ChuckW
Senior Member
 
ChuckW's Avatar
 
Join Date: Jun 2006
Location: Clovis, CA
Posts: 5,165
Likes: 0
Received 2 Likes on 2 Posts
Default RE: prop balancing

I used to balance them religiously. But these days I check them real quick with a fingertip balancer. As long as they aren't obviously, severely out of balance, I run them as is. If it is way out then I will spend a little time balancing it but I'll return it or toss it if it takes too much effort. I've found that APC props are usually pretty close for the most part, with only an occasional prop out of balance.
Old 06-03-2008, 07:25 PM
  #7  
alfredbmor
Senior Member
 
alfredbmor's Avatar
 
Join Date: May 2005
Location: El Paso, TX
Posts: 1,789
Likes: 0
Received 0 Likes on 0 Posts
Default RE: prop balancing


ORIGINAL: Insanemoondoggie

Any good mechanic well tell you ,if it`s a rotating assembly , it needs to be balanced . Some will tell you no and argue till the sun goes down , that it dont matter . But anything turning 10,000 plus rpms needs to be checked.
100% agree
Old 06-03-2008, 08:18 PM
  #8  
F-18
Member
Thread Starter
 
Join Date: Jan 2006
Location: East Kootnay, BC, CANADA
Posts: 87
Likes: 0
Received 0 Likes on 0 Posts
Default RE: prop balancing

ok thanks, i don't think my evolution 61nt will be going over 10000rpm anyways, but what is a fingertip balancer?
Old 06-03-2008, 08:20 PM
  #9  
HighPlains
My Feedback: (1)
 
Join Date: Mar 2003
Location: Over da rainbow, KS
Posts: 5,087
Received 4 Likes on 4 Posts
Default RE: prop balancing

The rest of the single cylinder engine is not balanced. Some engines run smoother with the heavy blade aligned with the crank counter balance.
Old 06-03-2008, 09:27 PM
  #10  
ChuckW
Senior Member
 
ChuckW's Avatar
 
Join Date: Jun 2006
Location: Clovis, CA
Posts: 5,165
Likes: 0
Received 2 Likes on 2 Posts
Default RE: prop balancing


ORIGINAL: F-18
but what is a fingertip balancer?
It is a simple, inexpensive balancer that you supsend between your fingers. It is great for use at the field but obviously it isn't quite as accurate as other types of balancers.

http://www3.towerhobbies.com/cgi-bin...?&I=LXK247&P=7

I also have one of these but don't use it nearly as often: http://www3.towerhobbies.com/cgi-bin...&I=LXHY61&P=ML
Old 06-03-2008, 09:36 PM
  #11  
Charlie P.
 
Charlie P.'s Avatar
 
Join Date: Feb 2003
Location: Port Crane, NY
Posts: 5,117
Received 8 Likes on 8 Posts
Default RE: prop balancing

Yes, you should balance props. Whether you should invest in a fancy balancer is a seperate issue. I have (and use) a simple finger-tip balancer. I balance all my props - and occasionally I find one that doesn't need balancing.

A simple "T"-pin held at an upward angle into the middle of the prop's shaft hole (so the tip is midway through the hole with the prop horizontal) will do for balancing. Scrape the front of the side that dips with a knife blade or sandpaper and repeat until it stays level.
Old 06-03-2008, 09:49 PM
  #12  
Jetdesign
My Feedback: (8)
 
Jetdesign's Avatar
 
Join Date: May 2008
Location: Honolulu, HI
Posts: 7,056
Received 0 Likes on 0 Posts
Default RE: prop balancing

This is an interesting topic, and I guess I haven't read more than a few posts on it in the past.

I use the finger tip balancer. I check the balance, remove the prop and flip around, then check the balance again. I do this a couple of times to make sure it is actually the balance of the prop that is causing any motion.

I just bought a 6 pack of Master Airscrew props. I balanced 3 so far, and one needed half a blade coated in acrylic to balance, another needed a quarter of the blade covered, the third was pretty close and just needed some 'extra' plastic around the edges sanded down.

I tached my engine last time I was at the field, and got 13000 rpm at full open throttle. To me it just seems smart and safe to check the balance of a hard plastic propeller spinning at that speed.

Now RCKen has been at this a LOT longer than I have, and his advice is always spot on. If there has been a time where I didn't take his advice, I probably regretted it soon after. He does say above to at least check the prop to be sure it's not wildly out of balance, but that a very balanced prop is not necessary. There are always cases where experience beats knowledge, or where practice beats theory. Maybe this is one of those cases.

This brings up the question though of what is considered to be wildly out of balance?
Old 06-03-2008, 10:19 PM
  #13  
ChuckW
Senior Member
 
ChuckW's Avatar
 
Join Date: Jun 2006
Location: Clovis, CA
Posts: 5,165
Likes: 0
Received 2 Likes on 2 Posts
Default RE: prop balancing

ORIGINAL: gaRCfield
This brings up the question though of what is considered to be wildly out of balance?
If one blade just sort of lazily falls I figure it isn't too bad. If I am in the mood, I may go ahead and make it perfect but otherwise it's not far enough to worry about in my opinion. That's for general sport flying of course. If I were racing or doing precision aerobatics, every prop would be unquestionably perfect.

I just bolted a brand new 11x6 APC prop on my GP Cherokee and you know how I balanced it? I held it on the tip of my index finger and it seemed to stay there without leaning one way or the other so I figure it's OK.

If one blade continually drops immediately though, then I consider that pretty far out of balance and I try to correct it. If it takes too much work to get it right though I get a little suspicious of that particular prop. I'd rather toss it in the trash than take a chance.

The Master Airscrew props are good for beginners since they will take a lot of abuse. Once you're confident that you won't have too many prop strikes though, try an APC or other high performance prop. The same diameter and pitch will often provide a very noticeable improvement.
Old 06-03-2008, 10:25 PM
  #14  
flymac
Junior Member
 
Join Date: Feb 2008
Location: Chicago, IL
Posts: 26
Likes: 0
Received 0 Likes on 0 Posts
Default RE: prop balancing

RCKen, do you and Minnflyer prefer one brand of prop over another? Also are wood props better than the "plastic" type?
Thank You
Old 06-03-2008, 10:35 PM
  #15  
Jetdesign
My Feedback: (8)
 
Jetdesign's Avatar
 
Join Date: May 2008
Location: Honolulu, HI
Posts: 7,056
Received 0 Likes on 0 Posts
Default RE: prop balancing

Well I"m not RCKen or Minnflyer, but most of the people I talk to like APC props; it seems to be the standard for the plastic props. I haven't used one yet, just because I bought a bunch of the Master Airscrews (because I thought they look better) and still have a lot left.

Wood props wont' take a prop strike as well, but are actually better performers as they don't flex like the plastic props do.
Old 06-03-2008, 10:38 PM
  #16  
RCKen
RCU Forum Manager/Admin
My Feedback: (9)
 
RCKen's Avatar
 
Join Date: Jul 2002
Location: Lawton, OK
Posts: 27,759
Likes: 0
Received 27 Likes on 24 Posts
Default RE: prop balancing


ORIGINAL: flymac

RCKen, do you and Minnflyer prefer one brand of prop over another? Also are wood props better than the "plastic" type?
Thank You
It depends on what your application is. Both Minn and I prefer to use Graupner props, but the are a little bit harder to get ahold of since Tower, Horizon, and most LHS's don't carry them, they have to usually be special ordered.

If I can't get Graupner props my next choice is usually APC props. Now I say usually because there are times that an APC, or a Graupner, just don't "look" right on the plane. In those cases I will usually use a Master Airscrew. Two examples here are my Hog Bipe and my Slow Poke.

Wood props are usually better than plastic/nylon/fiber filled because they don't flex nearly as much. But the down side is that if you even think about touching the prop to the ground with the engine running you can kiss the prop goodbye as it will shatter.

Hope this helps

Ken
Old 06-03-2008, 11:44 PM
  #17  
ErikElvis
My Feedback: (2)
 
Join Date: Apr 2008
Location: Middletown, DE
Posts: 468
Received 3 Likes on 2 Posts
Default RE: prop balancing

I bought a balancer and all but one of my props were out of balance. Like what was said above by RCKen as soon as you run through some grass or chip off some of the painted tips they are out of balance again. Im not taking the thing off and re-balancing it for a couple chips. At the field I really dont think its horrible to throw a prop on without balancing. But if I were at home I would take the time and check it since it only takes a couple mins to balance it. For a big prop on a larger plane I would probably be more diligent.
Old 06-04-2008, 12:01 AM
  #18  
ChuckW
Senior Member
 
ChuckW's Avatar
 
Join Date: Jun 2006
Location: Clovis, CA
Posts: 5,165
Likes: 0
Received 2 Likes on 2 Posts
Default RE: prop balancing


ORIGINAL: RCKe

It depends on what your application is. Both Minn and I prefer to use Graupner props, but the are a little bit harder to get ahold of since Tower, Horizon, and most LHS's don't carry them, they have to usually be special ordered.
I've always wanted to try a Graupner prop after hearing good things about them. Where are you finding them? Is just Hobby Lobby selling them?

As for wood props, I've found that they aren't necessarily all created equal. The J-Zingers just seem to perform better to me. One of these days I will get around to trying some of the Vess, Xoar and other props out there too.
Old 06-04-2008, 12:01 AM
  #19  
F-18
Member
Thread Starter
 
Join Date: Jan 2006
Location: East Kootnay, BC, CANADA
Posts: 87
Likes: 0
Received 0 Likes on 0 Posts
Default RE: prop balancing

o, ok i wasn't sure , thats a little less i have to worry about for the next flight, assuming i can get the props over the border into Canada from California before the summer ends. i have lots of questions and i hope you people have lots of patience...
Old 06-04-2008, 12:13 AM
  #20  
RCKen
RCU Forum Manager/Admin
My Feedback: (9)
 
RCKen's Avatar
 
Join Date: Jul 2002
Location: Lawton, OK
Posts: 27,759
Likes: 0
Received 27 Likes on 24 Posts
Default RE: prop balancing


ORIGINAL: ChuckW


ORIGINAL: RCKe

It depends on what your application is. Both Minn and I prefer to use Graupner props, but the are a little bit harder to get ahold of since Tower, Horizon, and most LHS's don't carry them, they have to usually be special ordered.
I've always wanted to try a Graupner prop after hearing good things about them. Where are you finding them? Is just Hobby Lobby selling them?

As for wood props, I've found that they aren't necessarily all created equal. The J-Zingers just seem to perform better to me. One of these days I will get around to trying some of the Vess, Xoar and other props out there too.
As far as I know Hobby Lobby is the only place to find them, or maybe a select few LHS's might carry them. Minnflyer has been using them longer than I have so maybe he will weigh in with a better source for them. He's actually the one that introduced me to these props, and I'm glad that he did. They are outstanding props and worth the extra effort it takes to get them.

Ken
Old 06-04-2008, 12:18 AM
  #21  
ChuckW
Senior Member
 
ChuckW's Avatar
 
Join Date: Jun 2006
Location: Clovis, CA
Posts: 5,165
Likes: 0
Received 2 Likes on 2 Posts
Default RE: prop balancing

I've only seen one in a hobby shop a couple hours north of here but a few guys at the field have said good things about them. I might order a couple tomorrow and give them a shot.
Old 06-04-2008, 12:25 AM
  #22  
flymac
Junior Member
 
Join Date: Feb 2008
Location: Chicago, IL
Posts: 26
Likes: 0
Received 0 Likes on 0 Posts
Default RE: prop balancing


ORIGINAL: RCKen


ORIGINAL: flymac

RCKen, do you and Minnflyer prefer one brand of prop over another? Also are wood props better than the "plastic" type?
Thank You
It depends on what your application is. Both Minn and I prefer to use Graupner props, but the are a little bit harder to get ahold of since Tower, Horizon, and most LHS's don't carry them, they have to usually be special ordered.

If I can't get Graupner props my next choice is usually APC props. Now I say usually because there are times that an APC, or a Graupner, just don't "look" right on the plane. In those cases I will usually use a Master Airscrew. Two examples here are my Hog Bipe and my Slow Poke.

Wood props are usually better than plastic/nylon/fiber filled because they don't flex nearly as much. But the down side is that if you even think about touching the prop to the ground with the engine running you can kiss the prop goodbye as it will shatter.

Hope this helps

Ken
Thank you RCKen, that helped quite a bit.
Old 06-04-2008, 05:40 AM
  #23  
da Rock
Senior Member
 
Join Date: Oct 2005
Location: Near Pfafftown NC
Posts: 11,517
Likes: 0
Received 2 Likes on 2 Posts
Default RE: prop balancing


ORIGINAL: F-18

I was going to order some new props for my alpha 60 when i saw an add for a prop balancer. i want to know how important it is ti balance a prop for a trainer and if i should invest in the balancer. thanks

A friend of mine flew his new Hangar 9 model the other day. The particular model has a belly bulge wood screwed to the bottom of the wing. There are about 10 tiny woodscrews through a plastic piece and no glue or anything else. He believes that you don't need to balance today's props. He lost about half those screws the first time he flew the airplane.

You will discover that our unbalanced props can vibrate at frequencies that will walk steel screws out that were tight to begin with. Matter of fact, it's often a good idea to not use steel bolts to hold a wing on. Nylon bolts are grippy and really don't respond to vibration like a hard metal bolt does. It's not a bad idea to retrofit metal bolts that hold critical pieces together with nylon bolts. And the wing is a rather critical component.
Old 06-04-2008, 09:13 AM
  #24  
Rufcut
Senior Member
 
Join Date: Apr 2004
Location: Ignacio, CO
Posts: 289
Likes: 0
Received 0 Likes on 0 Posts
Default RE: prop balancing

With all due respect to the Pro's on this forum, I always balance my props to reduce vibration to the airframe. I also balance my spinners. As da Rock pointed out, vibration can do some funny things to screws and bolts not to mention electronics. Also, I never sand on the prop to balance it, I use a little spray acrylic on the light side. If it needs more than that I just toss it. Any nicks or cuts to the prop and it hits the garbage. I know I sound a little obsessive and I do have to admit that I go through more props than most people. I'll accept a lot of cosmetic imperfections on my model but IMO engine and flight control systems must be maintained to the strictest standards. My 2 cents.
Old 06-04-2008, 12:35 PM
  #25  
WILDBILL M
Member
 
Join Date: Aug 2007
Location: Johnstown, PA
Posts: 54
Likes: 0
Received 0 Likes on 0 Posts
Default RE: prop balancing

Does anyone not balance the tires on their cars ??? And they don't turn anywhere near the RPM of any model engine...Don't balance your tires and they'll vibrate your false teeth out.. MY TWO CENTS Bill M.

Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service -

Copyright © 2024 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.