E-Flite Helicopters Discuss the line of E-Flite mini and micro helis including the Blade CP, CP Pro, Blade CX, etc

Two bolts on main shaft.... special steel or not?

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Old 05-20-2009, 07:46 AM
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tandem4
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Default Two bolts on main shaft.... special steel or not?

The two bolts on the main shaft, the one holding the rotor assembly and the other below the drive gears, are they made of any particular special steel or just plain bolts you can buy at a speciality bolt and nut store?
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Old 05-20-2009, 08:29 AM
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Default RE: Two bolts on main shaft.... special steel or not?

any metric 2mmX12mm i think is the size of thesocket head bolt with a lock nut will work
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Old 05-20-2009, 09:05 AM
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Default RE: Two bolts on main shaft.... special steel or not?

THANX!!!!!!
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Old 05-20-2009, 07:06 PM
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Default RE: Two bolts on main shaft.... special steel or not?

Hey TANDEM 4,

YEP as bad 400 said they are 2 mm x 12 and are steel. Sometimes the nut with a nylon insert in the tread to stop it from backing off in flight "YIKES" are not easy to find even here. So a standard 2mm nutwith LOCTITE will work.

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Old 05-21-2009, 09:54 AM
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Default RE: Two bolts on main shaft.... special steel or not?

Tandem,

+1 on the above two posts...

Glenn
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Old 05-24-2009, 08:20 PM
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Default RE: Two bolts on main shaft.... special steel or not?



I agree...





My question to E-Flight (Horizon) is... why is it that when you purchase spare feathering shafts they come with spare screws and washers but the main shafts do not?  My experience tells me that the screws on the feathering shaft "never" fail or bend because they are "captive" in the end of the shaft along the center line.  The weak point is where the blade grip meets the rotor head.



As for the main shaft - the torque is transferred through the two "2mm" screws!!  The first blade strike and bent shaft saw these bend.  This time the top one sheared. 



My opinion is that these two screws should be supplied with the shaft - otherwise you have to buy the whole fastener kit...



Jon

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Old 05-24-2009, 09:20 PM
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Default RE: Two bolts on main shaft.... special steel or not?

Jon6565,

A thought on this issue. My feeling is because we use Loctite on our F-Shafts screws they can become fouled if not cleaned up properly and most guys don't know how to remove the old Loctite so I feel thats why they are included. The other issue is, IF a F-Shaft screw backed out or broke, or got weakened by a blade strike someone is going to the hospital when those loose blades penetrate someones body, it possible. If a main shaft screw fails the entire head could come off but it would be contained. So thats my thinking, but still I am withya all that the 2 mm screws and nuts should come with new main shafts. If youve bent the mainshaft, youve stressed the two screws for the top and bottom of the shaft.
That just an old guys take on this issue.

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Old 05-24-2009, 09:50 PM
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Default RE: Two bolts on main shaft.... special steel or not?



Hi JPEE



No - I'm withyou on the safety front and also on the cleaning loctite aspect... I can see they're liability concerns!  It's more a case of why not with the Main Shaft.



About to source some after market ones now...



Jon

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Old 06-01-2009, 12:57 AM
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Default RE: Two bolts on main shaft.... special steel or not?

I am currently in South Africa on home leave. I will be buying quite a lot of spares before going back to Angola. I have a small Emco Unimat 3 lathe with a milling attachment. I will be cutting 5mm solid mainshafts, drilling the two holes and cutting the flat spots to take with to Angola.

I also downloaded the e-book Setup Tips for 400 Size RC Helicopters form www.rchelicopterfun.com

Really worthwhile book that gives a lot of tips as well as setup details to tame the Blade 400 for beginners.
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Old 07-03-2009, 12:36 AM
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Default RE: Two bolts on main shaft.... special steel or not?

I'm definately a noob and I'm off to a slow start. I Just got my b400 and had a couple blade strikes. After that the main rotors were not spinning at their normal speed. Then I noticed that the main rotors would actualy spin around freely with out turning any of the gears. I figured it might be the two screws on the main shaft but it is hard for me to tell. I don't see the nut on the top one and Idon't see the head on the bottom one. If I turn the rotors and hold the gears I never see any day light through the holes. Looks like the bolt maybe inside still. However, that doesn't make sense to me either if the blades turn freely. I'd appreciate any advice. I'm sitting here now with a big frown cause I'm totaly deflated now.
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Old 07-03-2009, 12:58 AM
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Default RE: Two bolts on main shaft.... special steel or not?

Welcome!

Cheer up Firefli! It's all part of the learning curve! we've all been there and done that - and will no doubt do it again!

From what you have described I would say there is a 99.9% chance you have sheared the two screws off in the main shaft. It is also feasible that the is a remnant of each left in the holes and that would explain why you can't see daylight. You will need to shine a flashlight into the holes until you see the shaft holes line up with the gear holes then punch them out with something 3mm or less in diameter. The shearing forces leave burrs that retain the remaining portion of the screw.

It is also my educated guess you have bent the feathering shaft as well.

You will see from my note above that I am still perplexed as to why e-flite don't supply the two M3 x 12 screws with the new shafts (it's a screw because the thread goes all the way to the head - bolts invariably have a plain part of the shank to the head). You get new screws with the feathering shaft each time but they don't bend! I disassembled the heli not so long back and one of these screws was bent and I didn't hit anything! To get these you have to buy a complete hardware set unless you can find a supplier.

Have you also checked your servo gears? Tail shaft? Fly Bar rod... all the usual suspects for blade strikes.

Jon
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Old 07-03-2009, 08:27 AM
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Default RE: Two bolts on main shaft.... special steel or not?

Thanks for your reply. It doesn't really look like there is a problem with the feathering shaft, should Itake it apart and replace it anyway, or does it need to be taken apart to really know if it is bent? How do Icheck the servo gears? Do Ineed to take them apart? Same with the tail shaft. If Ican't see that it is bent from a general glance should it be ok or do Ineed to take it apart to really evaluate it? Thanks again for you quick reply earlier. I don't have anyone to fly with and my LHS seemsto be lacking in thehelicopters departmentso Iusually have to drive an hour to gosee someone knowledgeable. It's comforting to get such good info so quickly in these forums. Thanks again.
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Old 07-03-2009, 05:20 PM
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Default RE: Two bolts on main shaft.... special steel or not?

firefli,

There is an easy way to check the feathering shaft without taking it all the way apart....

Just remove either main blade, and turn the screw in the grip of the removed main blade (it's 1.5 mm), this will turn the feathering shaft....then watch the remaining blade for any movement or wobble. If there is movement, the shaft is bent. If it' nice and steady as you are turning the shaft, then you are OK, the shaft is fine.

I used to take both blades off to check it, but it was pointed out to me that leaving the other blade on will magnify any problem with the shaft, making it easier to find a slightly bent shaft...it doesn't take much to mess up the flying characteristics of the heli...

The servo gears should be easy to check...just pop the links off of each one, and check that the servo arm moves very smoothly, without binding, jumping, grinding, or feeling rough. (do this while the heli is unpowered). If you feel something that is not smooth, it's probably a good idea to further inspect that servo by taking it off and apart to inspect the gears.

The tailshaft is pretty easy...just hold the heli very still, and rotate the main blades/rotor head clockwise, and watch the tailshaft very carefully for any movement that might indicate that it is bent. Usually it is obvious if it is. It can be very, very slilghtly bent, and not be visible with this check, but most times, this will suffice. Some guys go all out and check it with a dial indicator, but I have found that the visual I just detailed is pretty reliable...

BTW, if you guys need just the "jesus bolts" ...the screws that break off/bend in the mainshaft, here ya go, in quantity;

http://rtlfasteners.com/RC/cm2012.html

Or, if you would like stainles steel...stronger ones...

http://www.rcscrewz.com/product_info...roducts_id/281

They can also be found at most local hobby shops, under the DuBro name of products....they are 2mm x 12mm....

Hope this helps!

Glenn
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Old 07-03-2009, 08:01 PM
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Default RE: Two bolts on main shaft.... special steel or not?

Glen, thanks for your help. Your advice really helped me to get going in the right direction. I wouldn't have known how or what to check so your post was very educational for me. Thanks again. Should I pop off the links by hand or should a I get the tool for it? Idon't want to find out the hard way.
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Old 07-03-2009, 09:26 PM
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Default RE: Two bolts on main shaft.... special steel or not?

firefli,

You are welcome.

On the B400, I usually just pop the links by hand. Alot of the tools are too big to get where you need them on the B400 anyways, so I usually don't bother.

The ball link tools are handy on the bigger helis, where there is more room, and the links tend to be on alot tighter.

Good luck with it, keep us posted!

Glenn
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Old 07-05-2009, 09:02 PM
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Default RE: Two bolts on main shaft.... special steel or not?

Hey Firefli

Glenn corrected my mistake aboute the screws - they are M2 not M3! and that was a great tip about leaving a blade in to check the feathering shaft... noted!!

Hope you get up and running again soon.

Jon
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Old 07-06-2009, 04:24 PM
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Thanks for all the help. Iwon't be able to make it to the LHS until Wednsday, but I'll keep you posted thanks.
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Old 07-24-2009, 07:36 PM
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Default RE: Two bolts on main shaft.... special steel or not?

Well, I finally got the screws replaced and I had to replace the feathering shaft. It was a good learning experience. However, when I spin up the motor I still get vibrations. The Tail rotor looked good as well as the servo gears. I don't see any obvious signs of a a bent main shaft. Do you think that could still be it? What else should I look for? Also, I've been practicing on the Phoenix flight sim. I've learned that on the simulator, the heli wants to go foward and left. My helicopter seems to want to go back and to the right. I don't remember how it was before the damage. Should the flight sim be pretty simular to the the real thing?

Thanks in advance,

Robert

Turns out the shaft was bent. However, it still seems different than the sim.
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Old 07-24-2009, 11:12 PM
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Default RE: Two bolts on main shaft.... special steel or not?

Robert,

Good to hear that you got the heli smoothed out...

The helis on Phoenix and the real thing can both be trimmed using the trim controls on your DX6i....this takes some practice, and very still air for the real thing....it's hard to hold a steady hover when you are learning, but it's alot easier if there is no wind.

The trim adjustments work on Phoenix just like they do in real life, you could experiment with them on the sim first, with no wind to see how it all works...

Keep in mind to, that all RC helis (real ones too) always drift to one side (in the case of a clockwise rotating main shaft, like the B400 is, it's always to the LEFT) right as they lift off the ground. This is normal, due to tail rotor thrust, and it's called "translating tendancy" it's explained in more detail here;

http://www.rcheliwiki.com/Translating_tendency

Hope that helps some!!

Glenn
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Old 07-24-2009, 11:26 PM
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Default RE: Two bolts on main shaft.... special steel or not?

I'm not sure what I'm trying to achieve with the trim. On the coaxial I had it was easy. I just adjusted it until it would stay in a hover, but with the b400 on the sim it seems like the trim only works at a very narrow window. If I hover 4 feet off the ground I can make it stay still. If Iraise the elevation a little then I start to drift again. Is that normal? What should Ibe trying to achieve or how do I dial the trim in the right way? Thanks again for you response. I appreciate all the help you and this forum has provided.

-Robert
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Old 07-25-2009, 09:01 PM
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Default RE: Two bolts on main shaft.... special steel or not?

Robert,

You are welcome, let's see if we can get you on track....

First of all, hovering a single rotor, collective pitch heli is not easy...in fact, it's one of the hardest "steps" you'll encounter. Even now, after I've been flying for over a year, it's very difficult to hold a heli in a motionless hover, it's practically impossible in fact...it's not like the coaxials at all!!!

Hovering a single rotor heli requires constant small inputs in the cyclicl, rudder and throttle controls to keep in in a "perfect" hover, so it's going to be alot more of a challenge than the coaxials ever were...when you get some free time, go back to the coaxial heli on Phoenix and see how effortless it hovers compared to the B400!

The basics of setting trims in a hover is to acheive the most neutral hover possible, or as still as possible with no cyclic (right) stick inputs....you'll never get it to hover "hands off" for more than a few seconds, for reasons stated above, only coaxials can do that, it's the nature of the beast...

I've often heard it said that hovering a single rotor RC helicopter is very much like trying to keep a marble centered on a sheet of glass, by tilting the glass in whatever direction it takes to keep the marble centered...a pretty good analogy, I think...

The trims are there to give you a center point on which to work with the cyclic stick...so the better the cyclic is trimmed, the easier your job will be to keep it in a steady hover....so taking some time to trim on each flight ( a few seconds of hovering) is a good idea/practice. The point is not to get the heli motionless, but to keep it as close to centered with the right stick in the center as possible.

The narrow range of adjustment is normal, it takes very little input on the sticks, or the trim to make a change in the cyclic control of the swash/rotor head...

It will get easier with time and practice, I promise! At this point, I can't actually hover completely motionless, but pretty close...and I do it almost second nature...there is no substitute for stick time, both on the sim and especially in real life!!

Keep up the practice, and it will pay off!

Here's a short video of me practicing with the Trex 500 hovering....granted, it's a bit more stable than the B400, no doubt...but it's all about practice...I got a little bored, so I blipped the throttle a bit...lol...enjoy!

http://www.youtube.com/watch?v=iF3auuc8NuA

Have fun!

Glenn
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Old 07-25-2009, 11:39 PM
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Default RE: Two bolts on main shaft.... special steel or not?

Glenn,
That looked great! I noticed on the sim that when Iswitched my controler to the F. Mode it seemed easier to hover. I thought the F. Mode wasn't as easy to use for beginners but it sure seemed a lot easier. Is that all in my head or is there another explanation? Sorry for so many questions. I appreciater how complete all your replies have been.

Thanks,
Robert
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Old 07-26-2009, 12:53 AM
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Default RE: Two bolts on main shaft.... special steel or not?

Robert,

Thanks for the kind words! The Trex in that video is alot easier to hover than a Blade 400, and a larger heli is even more stable...the bigger, the more stable, and the more slowly everything happens... larger helis are actually easier to fly....but they sure do crash harder, and much more expensively...best to learn on the smaller helis first, in my opinion....

Yes, the heli in real life, and on the sim will be more stable in idle up, or "stunt mode" as Eflite likes to call it (and "F.mode"....very confusing at first!)

This is due to the higher head speed....think of a toy top or gyroscope you may have had when you were a kid...the faster the top/gyro is spining, the more stable it is....same thing applies here to the rotor disc on a heli....faster head speeds are more stable....BUT, they also increase the cyclic response...which is why it makes it more difficult for the beginner, not to mention it is just intimidating...the sound and speed of the rotor blades spinning that fast. I also have personally had a heli in idle up/stunt/f. mode get out of control much faster than it would have in normal speed...things just happen much faster when the headspeed is cranked up there....

So, more stable? YES.. Easier for the newbie? MAYBE... More intimidating? DEFINITELY...

It's up to you when you think you are ready for higher headspeeds...but that does not necessarily mean that the only way to have higher headspeeds is to go into idle up....changes to pitch and throttle curves, pinion changes, etc can also increase the headspeed in normal mode as well....but that is another topic...

One word of WARNING though....beware, that in idle up/f.mode/stunt mode, that the PITCH is affected as well as the rotor head speed...in other words, to achieve inverted flight, (which you would use f.mode/idle up/stunt for) you must have NEGATIVE pitch in the main rotor blades to fly inverted....

SO, that means that when you flip that switch, not only do you get higher head speeds, but the throttle/collective stick is effectively "cut in half" so to speak....everything ABOVE MID STICK is positive pitch...BUT, everything BELOW MID STICK is NEGATIVE PITCH....

What this means and what happens is that if you get in trouble, and slam the throttle closed, the negative pitch (assuming the heli is upright!) will SLAM the helicopter into the ground...because the negative pitch will drive it downward, in the same way that it keeps it airborne when it's inverted....you may have to picture this in your mind a bit....or better yet, try it on Phoenix....take a nice powerful electric heli like a Trex 500 or 600, and put it up about 30 feet in the air, and rapidly cycle the throttle/collective stick up and down in normal...and then do the same on f.mode/idle up/ stunt....you'll see exactly what I'm saying...[X(]

And it's alot better to find that out on the sim first....

Have fun!

Glenn
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Old 07-28-2009, 01:48 AM
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Default RE: Two bolts on main shaft.... special steel or not?

Well, I finally took it outside and gave it a try. I burned through one battery with happy hovering. Everything was working good and it handled much more like the flight sim. However, the next day I decided to try it again and for some reason as soon as I started to throttle up it went haywire. It seemed like some how the blades got stuck on something, the body started to spin, andit tipped onto it's side. I could not figure out what caused that. I ended up having to replace the feathering shaft again and Ifound a missing tooth on the top gear. I know the teeth were fine before because I checked it when I replaced the main shaft. I figure the tooth must have broken off from the blade strike. So far I have not been able to fly this heli very much. I've spent more time searching for parts and repairing it. I'm especially perplexed since this latest blade strike seemed unavoidable. The blades were spread out, I throttle up very slowly and I had just given it enough to start turning when this happened. Could the blades have somehow gotten stuck onthe flybar? Could it have been the gyro acting strange? It seemed fine yesterday. Ieven hovered today once before I had this mishap. As fun as it is to repair and learn how everything goes together, I'd really rather be able to fly it. Enough venting.

To the moderator:
If you want to move this to it's own thread, please do. Idon't want to hijack this thread anymore. It seemed like one thing lead to the next and I was torn between continuing my experience here or starting a new thread.

Thanks
Robert
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Old 07-28-2009, 08:25 PM
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Default RE: Two bolts on main shaft.... special steel or not?

Hey Robert

Glenn has given you some excellent advice in the posts above and I dont' think now that you are doing anything wrong - you are just plain "learning". The event you speak of where you have just bent your feathering shaft again... my guess is that the blades weren't set out straight when you spun up. The imbalance will just throw everything out. I did it twice the other week and bent two flybar rods in the space of 5 minutes...

Check that your blades are reasonabley tight in the grips. I heard the correct tension suggested like this recently:

If your blades are at 3 & 9 o-clock and you tip the heli on it's nose they shouldn't move. if you give the heli a little bump on the nose they should move down. But importantly - when you spin up make sure the are aligned with the blade grips and 180 degrees apart. If everything was set up right - it's the only thing it could have been.

These checks become routine but its easy to miss something. The other day I took off with the Gyro switch in rate rate mode (down) and also the rudder switch in dual rate mode. It was spinning like a good'n and I only just managed to land unscathed. Unfortunately we tend to learn by mistakes!

Hope that helped.

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