How to tell if a main shaft is bent or not

[Md001]

2 of them is brand new unused.....only worried as i hammered them yesterday because it was stuck in the one way shaft LOL ....but i have a feeling they might be in good condition...the other stock one i am sure 95% is bent. its slightly bent so hard to tell actually.. will give it couple rolls now.

prob best to just buy a new shaft then if your unsure lol

[kylelnsn]

prob best to just buy a new shaft then if your unsure lol

+1 No point risking it!

[dillwhacker]

Someone showed me this once....
Put it back in the heli, without the head. Spool it up so it is turning very slowly.
Then very very slowly and gently touch the side of the shaft near the top with a felt tip pen.
As soon as the pen touches take it away.
If it left a smooth circle of ink the shaft is straight. A bent shaft will have ink on one side and not on the other.

[1chris]

I don't believe this post, can't tell if a shaft is bent, should not be attempting to fly model helicopters, hammering the main shaft!!!!!!..........what!!

[David Drew]

I don't believe this post, can't tell if a shaft is bent, should not be attempting to fly model helicopters, hammering the main shaft!!!!!!..........what!!

Calm down!

Everyone starts somewhere and makes mistakes on the way. That's how we learn.

[Md001]

Conclusion: out of the 3 shafts: 1 standard stock + 2 new unused

stock one is definitely bent...but slightly, as i could see light under the shaft surface while it was rolling and the sound was inconsistent (gut feeling its bent + had 3 crashes with this one )

the 2 unused hardened shaft has consistent rolling sound and i could see very little light under the shaft surface while it was rolling..(much better than the stock)

So i guess the unused ones are 97% straight...maybe 3% damaged as it went under some hammering...

expecting a shaft which is in good working condition tomorrow so i will again run the rolling sound test and compare it.

From past experience i think slightly bent shafts are still useable because...the stock shaft i was using was surely bent, but my heli was very stable and smooth last time i flew it........but the person who set it up mentioned that the head was wobbling and maybe the shafts bent....but he did some fine tuning which kept the heli pretty stable.

thanks guys for all your support and advice.

regards.
md

[1chris]

I don't think "slightly" bent shafts are usable at all, should be disposed of

[Md001]

I don't believe this post, can't tell if a shaft is bent, should not be attempting to fly model helicopters, hammering the main shaft!!!!!!..........what!!

Not my fault...the main shaft was stuck inside the one way shaft.....there was no other way to take it out...so i had to hammer it down from top and eventually it came down from the bottom!!!! also the brand new shafts got stuck in the one way so i had to hammer them as well

i thought everyone hammered their main shaft as it needs to be secured and tight...i never knew it can be pulled easily by hands.....not my fault mate these shafts and heli parts can be crazy at times!

[Md001]

Someone showed me this once....
Put it back in the heli, without the head. Spool it up so it is turning very slowly.
Then very very slowly and gently touch the side of the shaft near the top with a felt tip pen.
As soon as the pen touches take it away.
If it left a smooth circle of ink the shaft is straight. A bent shaft will have ink on one side and not on the other.

Trev mate i was also told to check the shaft as you mentioned above except the felt pen bit.....i was told to take the head out spool it and see from the top how it goes round in a circle....

i would try the felt pen thing tomorrow when i get hold of the main shaft that is in good condition....its just a very lengthy procedure when you have 4 main shafts and have to assemble and spool them 4 different times! lol

but surely will give it a try

[pgkevet]

Often can release it with a good twist (mole grips). If things are really that tight then polishing shaft up with some honing compound (or similar) will make life easier

[pgkevet]

....its just a very lengthy procedure when you have 4 main shafts and have to assemble and spool them 4 different times! lol..

Another reason to just use an electric drill chuck..
You pick these tips up in time

[Md001]

being a newbie i did not have a mole grip in my tool box, but i did try WD40 to make it slippery did not work...at that situation i thought hammer would be the best tool...

Often can release it with a good twist (mole grips). If things are really that tight then polishing shaft up with some honing compound (or similar) will make life easier

[J-S-Q]

stock one is definitely bent...but slightly, as i could see light under the shaft surface while it was rolling and the sound was inconsistent (gut feeling its bent + had 3 crashes with this one )

For future reference, if you've had three crashes with the same main shaft then I think it's fair to say that it will almost certainly be bent. There's also a good chance that the feathering shaft will be bent. Obviously depends on how hard the crashes are and how lucky you are.

You will get the hang of all this eventually by the way! There's just a lot to take in when you start out.

[Md001]

ok can you please explain me the drill technique again because i got a drill machine.. also you sure that it wont damage the shafts surface??? just a bit cautious since everytime i lay my hands on the heli something goes wrong ..

Another reason to just use an electric drill chuck..
You pick these tips up in time

[David Drew]

Just gently nip it in the chuck and start the drill slowly. Watch the other end and see if it wobbles