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Old 05-30-2013, 06:06 AM   #1 (permalink)
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Default Gemfan is too brittle

Hi,
Just built a quad and went with the Gemfan props, these props are too brittle, just tightened them down and must have been too tight as they seem to just break and fly off at the center of the prop. tighten it enough for a good fit but don't over tighten. It's that place between too tight and not tight enough for me. Don't really like these blades.
going with some carbon fiber blades from RC Timer.
The carbon fiber blades are much stronger and won't give me this headache right?
Gemfan nylon/plastic
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Old 05-30-2013, 06:21 AM   #2 (permalink)
 
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Graupners were amongst the best, but they are discontinued. If you can find some, grab them!!

RC Timer CF are really good.
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Old 05-30-2013, 06:42 AM   #3 (permalink)
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Quote:
Originally Posted by Thalios View Post
Graupners were amongst the best, but they are discontinued. If you can find some, grab them!!

RC Timer CF are really good.

Yup, Graupners would be nice, expensive though!
I probably will go with the RC Timers
Thanks for the heads up!
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Old 05-30-2013, 08:01 AM   #4 (permalink)
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I found that when using Gemfans or "No Name" plastic props from HK, Always use a washer and only tighten 1/16th of a turn after contact...no more. Be sure to balance them and check that both sides track evenly.
I went to full Carbon Fiber and will not go back....PT
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Old 05-30-2013, 12:41 PM   #5 (permalink)
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What's the best way to adjust tracking on the Gemfans ETC, plastic props.

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Old 05-30-2013, 01:12 PM   #6 (permalink)
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...I would just tweak them slightly to bring one side up and one side down...If too bad, then run them under hot water in the sink...If worse than that...Chuck 'em!
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Old 05-30-2013, 02:18 PM   #7 (permalink)
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Quote:
Originally Posted by SurferOfTheSkys View Post
Hi,
Just built a quad and went with the Gemfan props, these props are too brittle, just tightened them down and must have been too tight as they seem to just break and fly off at the center of the prop. tighten it enough for a good fit but don't over tighten. It's that place between too tight and not tight enough for me. Don't really like these blades.
going with some carbon fiber blades from RC Timer.
The carbon fiber blades are much stronger and won't give me this headache right?
Gemfan nylon/plastic
I have had completely the opposite experience wit the GemFan props from Hobby King, they have been great. I have built and rebuilt a DJI 330, 450 x3 and 550 and a TBS Discovery and used the 8, 9 and 10 inch props and have not had any break in flight in hundreds of flights, I have split a few and continued to fly with them and while they would have caused some vibes they did not fail.

I will say that I do not use loctite and I am very careful that I do not over tighten the props and I always use washers, I always balance my props by using tape and never sand them.

I would be interested to know where you get your GemFan props as there does seem to be some variation in the quality.
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Old 05-30-2013, 02:19 PM   #8 (permalink)
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Quote:
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Yup, Graupners would be nice, expensive though!
I probably will go with the RC Timers
Thanks for the heads up!
Birddog also have some CF props a bit cheaper than the Groupners.

Pete
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Old 05-30-2013, 05:14 PM   #9 (permalink)
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wow wish i could say i have had no problems with gem fan. first prop broke mid flight barely got it down. so i went with washers and made sure i did not tighten to tight. well happened again about 15 flights in. i balance with tape. i am looking for a replacement as i am not using them again.
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Old 05-30-2013, 05:15 PM   #10 (permalink)
 
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RC-Timer CF props are my choice now that Graupners are gone.

XOAR are nice also, but expensive as hell.
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Old 05-30-2013, 05:25 PM   #11 (permalink)
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just ordered from rctimer. so i guess i just need to wait to see. meanwhile need to rebuild tbs disco after last prop failed. lost naza 1 motor both frames. ohwell
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Old 05-30-2013, 05:43 PM   #12 (permalink)
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Sounds like you got basic nylon gemfans. You should try the Carbon Reinforced or Carbon Fiber Gemfans.

Any Nylon prop will snap if you over tighten it. Its not a flaw.
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Old 05-30-2013, 05:44 PM   #13 (permalink)
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Quote:
Originally Posted by hjscm View Post
just ordered from rctimer. so i guess i just need to wait to see. meanwhile need to rebuild tbs disco after last prop failed. lost naza 1 motor both frames. ohwell
http://www.sierrarc.com/index.php?ma...0887mso30f7e36

That dude is local and carries the Carbon Fiber RCTimer props.
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Old 05-30-2013, 06:18 PM   #14 (permalink)
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Quote:
Originally Posted by Subaru4wd View Post
http://www.sierrarc.com/index.php?ma...0887mso30f7e36

That dude is local and carries the Carbon Fiber RCTimer props.
Any idea what the hole size is on these? Guessing they would have to be reamed to fit the 8mm DJI motors, thanks.
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Old 05-30-2013, 07:37 PM   #15 (permalink)
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No clue, i have never used them myself.

Some DJI motors have a notch and do not accept standard props.
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Old 05-30-2013, 07:54 PM   #16 (permalink)
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Yes I admit It I tightened too tight but still these nylon props are brittle and break easier than the CF would. I guess I learn the hard way, you get what you pay for. Must have the carbon fiber, Id feel safer with them.
btw is there any caveat in using blue loctight around the nylon props because I was using a bit on the threads.

oh yeah what size washers and what kind should I use?
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Old 05-30-2013, 09:05 PM   #17 (permalink)
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...EEEK! No Loctite on the prop shafts...Not needed
just use flat MM washers under the nut....
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Old 05-30-2013, 09:40 PM   #18 (permalink)
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i thought it was cause i tightened to tight the first time so second time i put a washer and didn't tighten tight at all. it was pretty windy out though. i will look at those props hopefully won't need to be reamed out.
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Old 06-01-2013, 02:24 AM   #19 (permalink)
 
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Quote:
Originally Posted by SurferOfTheSkys View Post
btw is there any caveat in using blue loctight around the nylon props because I was using a bit on the threads.
99% sure that's why your props broke.
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Old 06-01-2013, 06:42 AM   #20 (permalink)
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Default WARNING

Thank you both for that valued opinion concerning lock tight and nylon/plastic props.
Come to think of it, my problems all started right around the time I decided to use the blue lock tight. I had been flying without it fine. I was flying with 9 inch props( no lock tight) and decided to try some ( thinking I remembered reading somewhere to use the lock tight ?) on the assembly while changing the blades to 8 inch props. Well, I kept putting it up in the air (hovering) and ZING! the props would crack and fly off in either direction. Glad I only had it at a hover
NO MORE LOCK TIGHT AROUND THE PROPS!!!

Everyone reading this WARNING WARNING WARNING!!!
Thank you.
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