nuts5000

i have E -flight alum. upper head on my heli
took on a tree branch and down it came on the canopy
broken upper blades
so i replaced them but the blades now fit tight when you screw the two together
my guess is one of the blade stubsthat the blade slides on is bent just enough
to make the blades tight
time to buy another alum. head

SOO anybody else bend those little stubs on the upper head?????????

soloboss

I'm not saying that you are wrong.
But for what it's worth, I have been seeing blades that fit the aluminum head too tightly.When the blades are snapped together, they bind on the head. My solution is to sand away a bit of plastic in the area around the pis - where the blade mount is tight on the head. If you put the blades on and you don't feel just a bit of end play when you slide the blades on the pins, it's binding. Grab one of the blades at the tip and gently push / pull and look for movement.

Or maybe it is a bent pin. I know I have to sand about half of the blades I get.

Soloboss

shufflez

My first guess would be indeed a bent pin, as i've never had any problems with blades binding to the head. Now i'm really carefull with blades, so i only have tried 4 or 5 sets or so... Can you check the alignment of the pins opposed to eachother?

nuts5000

well i have been through about at least 50 sets of blades and now they dont fit after a crash, a little odd
but i will try sanding too.
easy fix, i hope- another upper head




the old saying
keeping throwing money at it
sooner or later it will be right (or fixed) LOL
thanx

soloboss

Shufflez,
This is turning into an interesting discussion. There has been a good bit of conjecture over the subject of upper rotor binding, so I decided to dig a little deeper. My personal interest is due to the purchase of a new bag of blades and - your guessed it, they bind.
I just measured a stock plastic head and an Eflight aluminum head, measuring the width at the root of the pin. I'm looking for the width across the land where the blades would contact the head.
I can't find a difference. I measured each 5 times and logged the numbers. I see the same deviation comparing the numbers. (it's tough to measure.) Averaging the width measurements shows no issues either. Thus my suspicion that the width of the aluminum eflight head is a touch larger than the plastic head is unfounded.
MYTH BUSTED

BUT, I do see our enemy MOLD FLASH at the parting line in abundance across the holes. I'm sanding away the "overbite" of the high side as it protrudes beyond the low side. I have to force the blades to lock together before sanding and there is a terrific bind when the screws are installed. Holding the blades at the tips, I cannot turn the blades on the pivot pins. After sanding there is ~ .010" of end play. And after that much sanding, I STILL see the parting line. That's significant flash.
The flash issue at the blade mount is certainly no myth.

On the issue of a bent aluminum pin, I have beheaded lots of stock upper hubs, but I never broke a plastic pin off. Those pins are in shear, not beam. They should break off, not bend as long as the blade mounts are locked / screwed together. If I'm wrong about that, please explain it to me. I must be missing something.
I have sheared plenty of pins from the stock lower head, but I put an aluminum pin into the plastic lower hub and resolved that.

So that's my opinion. What say ye?

Soloboss

soloboss

After replying to Shufflez about the bent pin, I do have to agree that your binding probably isn't caused by mold flash. Your problem is different. Are both pins seated fully? I'm not so sure that you could bend a pin that short if you wanted to, but it may be cocked in the head. How deep do the pins sit in the head? Are they deep, or are they shallow and glued in?
Seems to me that a pin that large in diameter and as short as it is wouldn't be able to force the 6061 alloy head to yield, but obviously something happened.

Is a pin loose and now it's pulled out of the seat a little bit? I'm really curious.
I do recall a past thread where someone needed to drill the holes out a bit as they also had blade binding issues. I don't recall if they were making the holes deeper or larger diameter. But the remedy did require a drill operation.

xyster101

I had a few sets of uppers bind on my aluminum head. just took a sharp xacto knife and cut off the flashing. Worked great!

stump3r

From my experience I have never been able to destroy or bend a blade pin on he upper hub, the weakest link in the upper assembly is the inner shaft, if you clip something hard enough you will twist or bend the inner shaft long before you snap off a blade pin. I have seen far too many substandard blades, have at least one bag of bad lower blades. The flash and overrun is a big problem and seems to be getting worse instead of better. Every set and I do mean every set of upper blades that I put on need some type of adjustment, either it's flash on on flybar ball or trimming required to ensure it won't bind....it's always something!

Wolfpackin

I have the MicroHeli upper and lower heads and I don't get any binding or friction with the blades on the upper head.
I do, however, have a very tight fit on the lower head and blades. It doesn't seem to cause any problems. The servos seem to have plenty of power to move them around.

Where exactly are you guys sanding and trimming?

soloboss

It's the flash around the stock blade mounts where they interface the hub. They aren't supposed to grip the head, but the alignment of the die that casts the mount is off and the blades grip the head tightly.

goldslinger

I agree, definately there is too much flashing from mis-aligned molds, exacto knife them and chamfer the holes that the hub goes into. Works everytime.

Gary

stump3r

Wolf, here are a couple pics to illustrate.

Pic#1,
This is the over run or chaff as I call it on the flybar ball link, must be removed to prevent the dredded TBE.
Pic#2,
Tough to see as my camera does not shoot nice macro shots, same thing here, over run or junk left over after the mold process, must be cleaned off to ensure it doesn't bind on the hub, same thing prevents TBE on upper and eliminates handling issues on the lower.
Pic#3,
Just to show what kind of junk blades I've been getting lately! Crud
Pic#4,
Properly spaced blade setup upper, notice the spacing between the blade and hub
Pic#5,
Lower spacing, this one is a little tight but still flies fine.

Wolfpackin

stump,

In this case, a picture is worth a thousand thanks.

I was going to ask for someone to post them but thought it would be futile.

Thank you, I had to sand the ball on the blades in the past but never really inspected the other ares of the blade mounts.
Now, after installing the MicroHeli lower rotor head, I have sticky lower rotors so I should probably take a look.

stump3r

Anytime buddy! Yeah I've had alot of issues arise from what appears to be the smallest thing on blades. Something as silly as a little over run on the flybar link balls caused me about two hours of tweaking trying to get rid of a minor case of TBE! It's always the small things with these heli's!

Wolfpackin

RE: Flybar Linkage

I just had to buy a new stock flybar and linkage because the linkage is not sold seperately.

After many removals, even with ball link pliers, I banged up the loop portion good enough to get some binding which translated to mild TBE.

Has anyone had this problem and tried to get the loop (with male threaded section) back into round and no burrs so that it is usable?

Is the linkage part available anywhere?

stump3r

LOL! Had to have a chuckle! Seems like we all go through the same things at one point or another. I looked high and low for that damn little linkage and zero luck...did the same thing and bought a new stocker just to get the linkage!

Wolfpackin

I'm glad you feel my pain.

Oh well, I just had three good flights tonight.
My CX2 looks and flys great with the silver MH parts.
I'll post some pictures after I finish a new flybar mod and minor canopy changes.

xyster101

Great post, but what is TBE?

BryFlyGuy67

Toilet Bowl Effect. It's where your heli wants to hover in a CW swirling pattern rather than a nice stable hover. It looks like the Heli is being flushed down a toilete, hence the name.

shufflez

Even though i don't use much blades (again, as they are $28 for a set of 4 here), i havent had too many problems with mold-flash. Although i do 'wet-sand' (with oil and polishing paper) the ball-linkages before usage. Give the balls a good wash after this ([X(]) and voila, one problem gone. The oil combined with polishing paper makes a really smooth surface. I do the same with the linkages themselves. Indeed, the linkages you get on 'after-market' flybars dont fit, but you can exchange the lowerpart with the stock one. Put one end in a vice and carefully push the other end in a bit, then start screwing. (Another stupid word-play no pun intended ).

nuts5000

well i pulled a set of upper blades out of a new bag
and well and behold tight fit on the alum. head and on my stock CX2
took the ones off the stock cx2 (that fit and work like should--they are from older stock) and tried them on my
alum. head cx2---fit and work fine

i doo belive it is from a bad run of blades
molds do wear out
hope the LHS exchanges them

now im not sure if the pins on the alum. head are bent
but i did buy another today
i think that pin is a press fit through the alum.

thanx