Fix for blade throws?

[birch]

[Disclaimer]
I am a newb and I do not own the mCPx. I am greatly anticipating the outcome to this blade throwing issue so I can go ahead and buy one for indoor hover and orientation practice.
[/DISCLAIMER]

I just looked at the exploded view of the mCPx and noticed that there is not washer between the screws on the feathering shaft and the bearings that they are resting against. Is this how it is on the heli or is it a misprint? It seems to me that, if the image in the manual is correct, then an appropriately sized washer would mitigate the catastrophic damage that could be caused by bearing kersplosions. Even if the bearing failed, the appropriately threadlocked screw with the appropriately sized washer would at least contain the blade while pitch control began to act erratically.

Thoughts?

[tracknoob]

Originally Posted by birch

an appropriately sized washer would mitigate the catastrophic damage that could be caused by bearing kersplosions. Even if the bearing failed, the appropriately threadlocked screw with the appropriately sized washer would at least contain the blade while pitch control began to act erratically.

Thoughts?

You'd need a stepped washer against the bearing in order to prevent binding against the inner and outer race, or better still, you would want a small thrust bearing in there.

The head is tiny, the standard cost target was a challenge, so we got what we got.

I haven't heard of anyone adding either a stepped washer or a thrust bearing yet, and I imagine it would require machining a deeper bearing recess pocket to allow the extra space needed... unless .... say, are there two head dampening 'o'-rings per side or just one? If there are two, then maybe go to a single dampener per side, and a stepped washer or small thrust bearing...

[birch]

I was thinking step washer as I wrote that, not sure why I didn't say it. I can imagine that a step washer of that size would be a challenge, thus the whole cost target.

Hrm, even with a washer / step washer I can imagine that a somewhat longer screw would be necessary.

I guess it was an ill thought out idea, should have thought it through more before throwing it out there. I hope that other bearings (Trex 250, etc) will be a good fix. I would really like to buy one of these but with the number of blade throws being experienced I have to pass.

[Mojappa]

There's already the step washer that's on the inner side of the grips, they just need a slightly longer shaft and the blade root modded for clearance from the screw head being farther as there's not much clearance stock.

[birch]

Ooooh, thanks for pointing that out. I had not noticed the step washer facing the inner bearing on the grip. Is the ID on that step washer sufficiently small to be securely held by the screw? I understand your other concerns regarding the shaft, just curious.

[Mojappa]

I would think it would be able to since the bearing does now and they're the same ID. A larger screw head would still be preferred.

[birch]

With more thought, I don't think this would be doable without a whole new feathering shaft because as you mentioned the shaft would be too short even if we could source a slightly longer screw to accommodate the step washer. From what I understand (and the exploded view doesn't really tell me) the feathering shaft only has one screw and the other side is permanent.

Shucks.

[755 robert]

Originally Posted by birch

With more thought, I don't think this would be doable without a whole new feathering shaft because as you mentioned the shaft would be too short even if we could source a slightly longer screw to accommodate the step washer. From what I understand (and the exploded view doesn't really tell me) the feathering shaft only has one screw and the other side is permanent.

Shucks.

Walkera feather shafts are longer and have a longer screw with a bigger head.I used one to mount double gaui bearings on mine.The inner step washer will not work on the out board side because the ID would have to be the screw size not the shaft size ...I checked...I would prefer a washer but I feel pretty comfortable with the set up I have...At leasst 50 flights so far with no probs.

[Gadflyii]

The only real fix I have seen thus far is to run walkera 4g6 blade grips w/ 4g6 feathering shaft....

There have already been some feathering shaft failures in addition to the blade grip failures.

[recurry]

Originally Posted by birch

I would really like to buy one of these but with the number of blade throws being experienced I have to pass.

Just exactly - or even inexactly - how many blade throws are their really. I'm reading about them here but I know at least five people who have had them for a week and a half with no problems. My self included. I know that one of mine came with a loose grip retaining screw that would have resulted in a blade throw but it also came with a sheet of paper that said to check it. I did and now no problems. I also know that the LHS where I bought mine from got 16 in his first batch and says no customers have reported blade throws. I was also at the local HobbyTown tonight grabbing some spare parts before they are all backordered (most are) and the manager there says they have sold out until next week except for RTF and he's not heard of a single blade throw from his customers or from any of the managers in nearby stores.

So, how big of a problem is this really and for those that are real are they really bearing failures or user failures. Of the ones that are bearing failures (if any) how many blade strikes did those machines have before the failure and was the feathering shaft screw properly tightened beforehand.

I think there are a lot of questions that aren't being asked or disclosed and a lot of really wild statements being made (like one thread that says Hobby Towns are pulling them from the shelves) that really cast doubt on this entire situation.

Maybe there is a major problem - the verifiable facts I've seen don't support that. What the verifiable facts seem to support is there is a problem with ships being delivered with loose feathering shaft screws and that a FEW ships let loose blades before HH got the word out to all dealers to include a page cautioning all buyers to check that (among other things).

Before I'd make decisions about whether something has a real problem or not I go to a reliable source - HH, LHS, - not just a bunch of people hiding behind handles on a public forum.

For those of you who perhaps really did have a blade throw due to a bad bearing, you have my personal apology if I've offended you but if you have any experience and pragmatism at all you must admit this has gotten out of hand in a big way.

[andypants]

@ recurry - my experience is thus. I got one of the first anywhere, tore down the head, added the threadlock they didn't and set it all up again. Henceforth, I flew it. The first bearing lasted ten minutes, the second, which was the T-Rex replacement, lasted a few more. That's the story. I'd embellish it, but alas.

Did I crash it? A few times. Nothing too terrible. Certainly nothing that would degut a bearing. But hey. We live, we learn, we shelve it until new bearings arive and don't fly it at eye level ever. Never, ever. I know you haven't seen it, but they fly off at a rate of knots and it's quite startling.

[HBJ069]

Well I dunno, I bought one of the first also and have well over 100 crashes/flights and not 1 single bearing issue! I have modded the boom, landing gear, battery size and still flying great. All the folks that are stating these little fellas a junk are in fact forgetting that "most" align helis shipped are missing loctite, loose screws, etc and I have yet to see a groundbreaking rc item that didnt have a flaw of some sort.

Now on to the failures vs production, how many of these MCPX's have been built? anybody? How many have been reported on this site as good? how many bad? finally what is the true failure rate? Somebody should do a poll on this so we can see the facts.

Legal liability, There are some Hobby Shop owners that may be afraid of this and that could be the reason they are being pulled, I have a few contacts at the worlds largest Hobbytown USA and they are not pulling any and have in fact a waiting list for the next batch.
There will always be rejects in every batch of products produced and over time those faults will be corrected. Have patience, HH didnt get to where they are by producing junk (my opinion) and I feel confident they will have a solution soon.

[shock]

Originally Posted by Gadflyii

The only real fix I have seen thus far is to run walkera 4g6 blade grips w/ 4g6 feathering shaft....

There have already been some feathering shaft failures in addition to the blade grip failures.

Is this a direct swap? May as well use a system that is tested and true while the stock part issues are worked out.

[birch]

Recurry - While I was reading about blade throws on the mCPx forum here, I decided to do some searching. Someone at RCGroups has compiled a list of forum reported blade throws from a wide range of forums, including overseas forums and of course Helifreak as well. I am not trying to be a sensationalist and trust me, it is very hard to get me to follow crowd mentality especially on forums.

There does appear to be a real issue, and it seems to appear randomly. When I first posted last night after looking at the exploded view in the manual I came to the conclusion that this might simply be an oversight in engineering. I am not sure that bearings and especially tiny, fragile bearings are meant to be the focus of that much force. Again, I could be wrong here but when I look at other head designs, for example the SR, I see bearings that are retained by step washers.

I am not trying to slam E-Flite here, I like them. My only reason for starting this thread was to throw out a suggested fix and possibly hear back from folks with far more experience than I have. I am greatly anticipating a fix for this issue so I can get a mCPx.

[birch]

Originally Posted by HBJ069

Well I dunno, I bought one of the first also and have well over 100 crashes/flights and not 1 single bearing issue! I have modded the boom, landing gear, battery size and still flying great. All the folks that are stating these little fellas a junk are in fact forgetting that "most" align helis shipped are missing loctite, loose screws, etc and I have yet to see a groundbreaking rc item that didnt have a flaw of some sort.

That was certainly not my intention. I was merely addressing a specific issue that appears to be affecting quite a few people.

[freeze]

I found the ultimate fix.

I called Horizon and am shipping it back for a full refund.

[Mojappa]

Just curious, how many crashes do you guys think it takes before it changes from a defective bearing to crash damage? For me, I've had 7 crashes, nothing broken, in 45 flights so at this point I'd have to say that if my bearing failed it would be due to normal wear. Not saying these bearings are ideal by anymeans but like with the tail motors on the SR's, for every actual defective motor that was reported there were 12 that had been through crashes beforehand and still tried to say the motor was faulty.

[755 robert]

Originally Posted by Mojappa

Just curious, how many crashes do you guys think it takes before it changes from a defective bearing to crash damage? For me, I've had 7 crashes, nothing broken, in 45 flights so at this point I'd have to say that if my bearing failed it would be due to normal wear. Not saying these bearings are ideal by anymeans but like with the tail motors on the SR's, for every actual defective motor that was reported there were 12 that had been through crashes beforehand and still tried to say the motor was faulty.

I think you make the point of the day.With any of my other helis one tip over and I am replacing parts.People are looking at this thing like a toy,not what it is,an rc helicopter and nowhere have I seen HH claim that it is crash proof..

[Ozz58]

Originally Posted by 755 robert

I think you make the point of the day.With any of my other helis one tip over and I am replacing parts.People are looking at this thing like a toy,not what it is,an rc helicopter and nowhere have I seen HH claim that it is crash proof..

Yep, I can tell you this, when I crash my 500 the main bearings almost alway get notchy. This could be part of the issue. Although I keep going back to one post that said something like his/her 2nd flight the bearing failed. Think it true?

Craig

And what do you mean it's not crash proof??

[Mojappa]

I'm not doubting that some have had legitimate failures. Too fuzzy now but someone on RCG had a blade go on the first spool up, but I can't remember if this was a bearing or a non-checked spindle screw. Too many variables.