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Old Jul 28, 2010, 01:39 AM
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ajbaker's Avatar
Lincoln, CA
Joined Oct 2006
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O-ring vs. collet

IMO, there is no reason whatsoever to use the stock prop-saver on a CF. The only way (barring totally obtuse aerobatics gone wrong) the prop could hit the ground is if you accidentally landed inverted with the motor running. Very unlikely. Therefore, a prop saver is not desirable on the CF. However, after 150+ flights on mine with the stock prop saver, it finally broke the original stock rubber O-Ring while I was putting it on. I always take it off when it is stored. I have never had a single problem with the prop saver at all. A prop that is in balance does not care what is holding it on. I have several planes that use a prop-saver for what it was intended for - saving the prop on those "less than perfect" landings or takeoffs. Because of all the exposure I have to collet vs O-Ring, I can state categorically that it is much, much easier for me to detect an out of balance prop on an O-Ring type mount than it is with a collet. This all brings me back to your situation. Make another short video like you did after you balance the prop. You will easily notice a significant difference in the sound. Then, by all means, I encourage you to switch to a collet type mount. Years ago (too many to count), when prop savers came into being, they were a real luxury when props were expensive and I was flying U-Control planes. Overall, I do not necessarily prefer one type over the other. I simply use whatever is called for based on the airplane application. If anything, I slightly prefer Collet mounts. I hate the set screw mounts - but, that is a whole other story. Enjoy and take some videos of your flights for all of us to enjoy.
AJ
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Old Jul 28, 2010, 01:49 AM
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I never take out the o-ring , its that a potential problem?
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Old Jul 28, 2010, 01:55 AM
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I'm not sure I know what a "collet type" is, come to think of it. When I said to make sure it was tight, I meant the threaded adapter with the cone/nut. Because its a pusher, it goes with the thread and works it out rather than working it tight.
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Old Jul 28, 2010, 01:57 AM
Argue for your limitations
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Lincoln, CA
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Remove vs Leave an O-Ring installed

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Originally Posted by JLT_GTI View Post
I never take out the o-ring , its that a potential problem?
I will bet that you could start a whole thread with that question. So, I will just give you my take on the situation. It is logical to me that the rubber o-ring is just like a rubber band and as such will lose it elastic properties after being stretched for a long period of time. It seems to me that it would make it more prone to failure upon use. Therefore, I "unload" the O-Ring when I store the plane in my hangar. I want to read other views on this, too. There are probably many "right" answers to this one. This just happens to me my answer. I reserve the right to be wrong as always.
AJ
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Old Jul 28, 2010, 02:03 AM
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As long as you reserve that right, you're never wrong. Right?
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Old Jul 28, 2010, 02:11 AM
Argue for your limitations
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Lincoln, CA
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Threaded power shaft

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Originally Posted by s_mack View Post
I'm not sure I know what a "collet type" is, come to think of it. When I said to make sure it was tight, I meant the threaded adapter with the cone/nut. Because its a pusher, it goes with the thread and works it out rather than working it tight.
Ah, yes. I see what you mean. And, the collet type of mount "squeezes" itself onto the prop shaft. HERE is a very popular one. I am sure you can see how it squeezes the shaft.
You are 100% correct in saying that the prop WILL want to come loose based on the motor (with a threaded output shaft) turning CW when viewed from the rear. Then, the nut can (and does - ask me how I know) come completely off along with the prop (this condition could be a safety issue, too). Of course, I found the prop fairly easily (4-5 times) and I never found the nut (except the one running the transmitter). Then, YES. Your suggestion to make sure the nut is tight is a great suggestion.
AJ
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Old Jul 28, 2010, 02:12 AM
Argue for your limitations
ajbaker's Avatar
Lincoln, CA
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As long as you reserve that right, you're never wrong. Right?
Hmmmm...... I guess so....
AJ
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Old Jul 28, 2010, 02:14 AM
An Aussie in Dubai
United Arab Emirates, Dubai
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Quote:
Originally Posted by s_mack View Post
I'm not sure I know what a "collet type" is, come to think of it. When I said to make sure it was tight, I meant the threaded adapter with the cone/nut. Because its a pusher, it goes with the thread and works it out rather than working it tight.
This is one collet that would be suitable...
http://www.hobbyking.com/hobbyking/s...idProduct=5122
or this
http://www.hobbyking.com/hobbyking/s...idProduct=5677
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Old Jul 28, 2010, 02:22 AM
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Aren't those prone to the same CW thread problem? They all have a nut on the end that is spinning with its thread, no?

Anyway, this is the one I used... but after losing the prop and nut/cone on the first run... I HIGHLY recommend getting a 5mm posilock nut from your hardware store. Its the metal nut with the ring of plastic inside. Only thing is, you should only use the nut ONCE.
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Old Jul 28, 2010, 02:46 AM
An Aussie in Dubai
United Arab Emirates, Dubai
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Originally Posted by s_mack View Post
Aren't those prone to the same CW thread problem? They all have a nut on the end that is spinning with its thread, no?

Anyway, this is the one I used... but after losing the prop and nut/cone on the first run... I HIGHLY recommend getting a 5mm posilock nut from your hardware store. Its the metal nut with the ring of plastic inside. Only thing is, you should only use the nut ONCE.
I would avoid those like the plague.
You see the grub screw applies pressure only from one side and this pushes the adapter and prop off centre and therefore out of balance.
Secondly, the grub screw can mark/damage the shaft.
With the collet design the adapter and prop are held concentrically and it doesn't mark the shaft.

Yes, there is potential for the nut to come loose due to direction of rotation but I personally have never experienced any loosening of the nut.

If in doubt, a wrap of plumbers tape on the thread would act to stop any loosening or a drop of thread lock (Loktite) if you have it.
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Old Jul 28, 2010, 02:50 AM
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If you tighten the collet TIGHT on the CF, it will stay put. The prop load on the nut is not so great with such a small prop and such a large (5mm) prop shaft and nut to cause undue concern.

On the other hand, a prop saver is ESPECIALLY bad on a pusher if the prop uses inserts to match the motor shaft, because the insert is on the BACK end of the prop near the end of the shaft, where it can come unglued with use and come out of the prop. And there goes your prop...! Not to mention the fact that the bulky rubber O-ring adds an imbalance all by itself even if you balance the prop unless you are very lucky to get equal weight and position of the ring on both blades. It's not so much an issue with larger, slower turning props, but with a 5 in. prop turning at high rpm, it can and usually does result in much less smoother running motor of the motor on the CF than with a collet.
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Last edited by Tom Frank; Jul 28, 2010 at 02:57 AM.
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Old Jul 28, 2010, 03:31 AM
Argue for your limitations
ajbaker's Avatar
Lincoln, CA
Joined Oct 2006
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Quote:
Originally Posted by s_mack View Post
Aren't those prone to the same CW thread problem? They all have a nut on the end that is spinning with its thread, no?

Anyway, this is the one I used... but after losing the prop and nut/cone on the first run... I HIGHLY recommend getting a 5mm posilock nut from your hardware store. Its the metal nut with the ring of plastic inside. Only thing is, you should only use the nut ONCE.
That is why I said on the first post of this page that I hate set (grub) screw type. Of all the choices that you had, IMO you picked the worst of them all. Not only for the reasons that you experienced but the ones that pghern mentioned also. I could add to that list. But, the best thing you can do is toss that adapter in the trash and get a collet type adapter. Even the O-Ring adapter is much better than any grub screw type. Ah well. Hopefully everything will work out and you can finally settle into some great flying times. Please take some videos to share with all of us.
AJ
P.S. As far as the cone or nut coming loose from holding the prop, I have never had that happen to me on any and all collet type adapters that I have ever used. I just use whatever household nail fits in the little hole in the cone and tighten it as tight as I can.
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Old Jul 28, 2010, 03:39 AM
Argue for your limitations
ajbaker's Avatar
Lincoln, CA
Joined Oct 2006
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Quote:
Originally Posted by pghern View Post
This is one collet that would be suitable...
http://www.hobbyking.com/hobbyking/s...idProduct=5122
[/url]
I have a few of those and I don't like them because they require too big a hole to be drilled into the prop (1/4"). Then, the prop can't be used anywhere else because the little plastic adapter rings are too small now. The other one you had posted is my favorite of all the adapters. However, that said, the adapter above is perfect for the 6x3 TGS prop that I use on the CF. I don't need any adapter ring to mount the prop.
AJ
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Old Jul 28, 2010, 07:10 AM
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BTW guys.. im quite far from "expert"..

but in miliamperios (spanish forum) , one user posted this:

http://www.hobbycity.com/hobbyking/s..._Motor_%2819g#

Whats wrong with this motor? Or what am i ignoring?

Because 2100Kv, 2/3S , and max current draw 7A.... (unless its without propeller and the A draw triples... ) .. it sounds like a much better replacement engine for the CF..
So thats why im certain that im ignoring something big...

edit:
Test Data:
Battery: 11.5v
Current: 7.2A
Propeller: 5x3
Thrust: 337g
Speed: 18570rpm

Ok.. with a 5.5 it would certainly draw more amps.. but it seems unlikelly to deliver the 800g thrust the CF manages acording to some folks here (337g with 5.3)
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Old Jul 28, 2010, 07:44 AM
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Quote:
Originally Posted by JLT_GTI View Post
BTW guys.. im quite far from "expert"..

but in miliamperios (spanish forum) , one user posted this:

http://www.hobbycity.com/hobbyking/s..._Motor_%2819g#

Whats wrong with this motor? Or what am i ignoring?

Because 2100Kv, 2/3S , and max current draw 7A.... (unless its without propeller and the A draw triples... ) .. it sounds like a much better replacement engine for the CF..
So thats why im certain that im ignoring something big...

edit:
Test Data:
Battery: 11.5v
Current: 7.2A
Propeller: 5x3
Thrust: 337g
Speed: 18570rpm

Ok.. with a 5.5 it would certainly draw more amps.. but it seems unlikelly to deliver the 800g thrust the CF manages acording to some folks here (337g with 5.3)
it weighs 19 grams... that motor is way to small.
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