EXI 500 build

[hoverless]

[CPV2]

Well I took it to work this week and we have smooth painted cement floors.
Adjusted the tail servo back and forth and got it pretty good.
flipped it to head hold and the tail was rock solid.

2 seconds later at about half throttle the heli made a loud noise and started vibrating.

One of the tail blade grip holder screws broke and the blade and holder disappeared, other blade broke, the immediate imbalance took a couple teeth out of the tail drive gear.

I looked all over the shop for the missing blade grip.
Went and got lunch and was sitting next to my tool box and started looking around thinking maybe it landed on top of one of the garage doors that are all up.

Looked up and there it was.
A 4 inch hole in the sky lite, 25 feet up(this is 1/4" thick plexi glass).
Got out the tall ladder that barely makes it to the roof and got up there and yes, there it was(intact blade and grip), sitting 5 feet from the sky lite.

Ordered a plastic Align blade grip assembly and tail blades and slider.

Will try this again this coming week.

Good thing it did not hit me in the head, or any where else for that matter.

Just my opinion here, but when we start moving into the 500 and larger class heli's, we need to take a step back and make certain that we have acceptable parts.

I went through the head and it seems fine.
I even went through the tail and thought it was fine.
I think it needed a hardened screw for the blade grips instead of the soft screws that they come with, cause it just sheared.

Lesson learned.

Clarence

[Ber60]

Hi Clarence, you are very lucky because those things fly of at the speed of a bullit ,I hope they are not mad at your work for punching a hole in the sky lite

[CPV2]

Yah, the boss was not real happy, but better a hole punched in the skylite than a hole punched in my head

I will treat the 500 and all heli's from now on with RESPECT, period.

Clarence

[hoverless]

Holy Smokes! Talk about a heart stopper! I'm glad you're OK!

This begs the question: How in the heck can a person tell the difference between a soft piece of metal and a hard one? Also, would it be wise to contact EXI and let them know what happened? You may not get a response but if this is a quality control problem there could be other kits designed with the same flaw in them too and someone could be hurt...or even killed under the right circumstances.

I have a EXI 500 kit coming and now I'm wondering what parts can be trusted on it. It's like playing Russian roulette!

[B2TheEYo]

Yikes, glad no one was hurt and you walked away with clean pants!

Truth be told, the 500 class is one of the most dangerous birds around due to the emence forces it's tail rotor produces, making scenarios like this far to common. Look at Tom, he's had his whole tail explode.. LOL Mainteince checks before and after every flight is crucial and using nothing but high quality materials and parts in all the right places.

I've had glass fiber tail blades explode mid-flight, for NO reason. Never could find them after.. Came to find one a month later, half way through my sheds half-inch plywood wall over half a acre away where I was flying... Pretty scary, that would have zipped through someone head like nothing, easily.

I got max respect for my 500, it may not be as dangerous or serious as being hit by a larger birds mains, but if it's tail goes, it's easily just as bad as a 90's mains going off under the right circumstances.

It's kinda funny how the extreme dangers of this hobby kinda take a back seat and almost seem like they don't exist, I guess we're a crazy batch! Main blades spinning at 3000RPM and we go eye level with them to see if they track! Bahaha! Completely nuts if you think about it.

Hoverless, I wouldn't necessarily worry. But, ensure you use locktite/threadlock on all screws going into aluminum, and superglue all screws in plastic. Pulling on the parts have assembly is always a good measure. Once I get something together, I'll work it and pull on all it's joints and what not to see if I have any give or weord slop

[ptc]

Originally Posted by CPV2

One of the tail blade grip holder screws broke and the blade and holder disappeared,

I have had this exact same thing happen twice with my EXI 450.

Phil

[hoverless]

So...Mike and Phil...have either of you guys swapped out any screws in the tail assembly or anywhere else on your heli's with upgraded screws to be sure the same thing doesn't happen again? If so...what kind did you buy?

Since were on the subject of "things coming apart"...is there a vendor that sells a complete screw/bolt set for RC heli's online? If there is I'm thinking it would be a great idea to buy a set before I begin building the EXI 500.

[B2TheEYo]

http://www.rcscrewz.com/

Great place Steve showed me, they sell Stainless Steel screw sets for all models, and quality bearing sets too.

[ptc]

Originally Posted by hoverless

So...Mike and Phil...have either of you guys swapped out any screws in the tail assembly or anywhere else on your heli's with upgraded screws to be sure the same thing doesn't happen again? If so...what kind did you buy?

Since were on the subject of "things coming apart"...is there a vendor that sells a complete screw/bolt set for RC heli's online? If there is I'm thinking it would be a great idea to buy a set before I begin building the EXI 500.

I replaced them with the same screws. If it happens a third time I will look for some harder screws.

If I get a 500 I would probably replace them before the first flight.

Phil

[hoverless]

Thanks Mike for the link! I'm going shopping!

Phil...you said a mouthful and I won't trust the stock screws/bolts.

I'm looking at the website Mike posted and don't see a screw set for the EXI 500 but I've heard that that heli matches the Align Trex 500 so the screw set offered for the Trex 500 should work? What do you guys think? I'm going to contact them and ask if they know it it will work.

Well...I sent them an email and will see what they say and let you guys know what I find out.


Clarence...have you found any other damage besides what you listed?

[B2TheEYo]

The EXI, CopterX, among others are identical Trex clones. Though some of the HobbyKing kits do vary a tiny bit, same designs but sometimes things are off a tad bit, which is to be expected for the cost...

[hoverless]

Mike...that's what I've read too.

I just got a reply back from RCScrewz and Keith said the Align 500 screw kit would work for the EXI 500 so I just placed an order. I don't want to have the same experience Clarence did and am willing to replace the important screws to be on the safe side.

[B2TheEYo]

That 500 is totally gonna be bling'd out too! Nice shiny Stainless Steal screws beats the old black soft stock ones.

I was gonna get the kit for my HC500 back awhile ago, but just couldn't spend $50 on screws.

[hoverless]

LOL...

It would be a first for me to own a "blinged out" heli.

After reading what Clarence posted about his bad experience I don't mind spending the extra $$$ (cost $29.00 shipped from RCScrewz) to know I won't have to duck for cover on startup.

[B2TheEYo]

Too true.

You'll love the 500, I love mine. Almost considering getting a second one if I can get the cash from selling a few things I got laying around.

[hoverless]

I was just sitting at the kitchen table with the 500 out of the box and the 450 Pro was sitting next to it and looked dwarfed! I've been building the 450 and found my fingers weren't fitting into some places easily. After handling the body of the 500 I know I'm going to love it!

Something I need to ask about since I'm new to heli's is...the motor that came with the 500 does not spin/rotate around freely but instead it feels like it stops against something unseen to the eye no matter which way you try to turn it. Is there an arming thing that happens with the motor once it has power to it and unlocks it? The motor on the 450 spins freely so I'm puzzled about this. Maybe it's a bad motor?

[B2TheEYo]

The size difference makes working on these things a lot easier, that's for sure!

As far as the motor.. It turns right? It just feels to lock into notches when you turn it right? If so that's perfectly fine, in fact that's awesome, as that means it's gonna be a strong motor. Strong magnets mean a strong motor. My HDX850 motor is so wore out and old the blades just moving from gravity is enough to cycle my motor around.

But if you're unable to turn the motor completely, maybe a screw fell into it? Had that happen to my 250 on it's FIRST flight. What a bastard that was to get out. LOL

[hoverless]

Well the motor begins to turn (in either direction) but then stops suddenly as if it's being stopped by something internal...sort of a clunk sound like it's hitting something inside out of sight. The motor on the 450 has that ratcheting feel to it as it turns and is able to complete the turn/spin cycle. The 500 motor definately is not able to complete a turn (maybe turns 1/4 turn) before something is stopping it. As you mentioned...maybe there is a screw inside causing the problem? If that is the case then I'll have to do motor disecting 101 and figure out how to get it apart to be able to see inside what's causing the problem.

[B2TheEYo]

Sounds like that's the case. Opening a large motor like that is pretty straight forward. There should be a few grub screws on the out runner, on the bottom of the motor to remove it from the shaft, and a C clip on the top of the motor on the shaft. Take you're time and it's straight forward.

Maybe shine a light inside of there and look it over, and if you have anything thin like a took pick, fish it in there and swab it around to see if it fetches anything.