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Atom 500 › Crashed my Atom 500; I need some questions​answered.....
02-15-2011 04:54 AM  6 years agoPost 1
BOB WHO?

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Downey, Ca.

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I'm going to have lots of questions here and some of them are going to sound, well....dumb. I operate under the following premise; 'a stupid is question is better than a stupid mistake'. So now that I have that out of the way here we go: How is the main shaft removed? The head is off, the cap bolts are out, the mast lock is loose and the main shaft won't budge. Also the blade grips are still installed (the spindle doesn't appear to be bent) but the bearings feel slightly notchy. This is the first crash I've had and I believe it's the first crash for this model (I bought it barely used). The crash was not too bad but both blades (stock) were damaged. What are the odds of blade grip bearings on both sides being damaged?

EDIT: When I pull the main blade grips apart the notchy-ness disappears so I'm not really concerned about the blade grip bearings although I see that the spindle is slightly bent.

So I'm still stuck trying to remove the main shaft after the cap bolt and head are removed. Also the top bearing block won't slip off the main shaft after the screws are removed from it.

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02-15-2011 02:46 PM  6 years agoPost 2
darkfa8

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Brick, NJ - USA

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If the top bearing block won't slide off the main shaft then it's a clear indication the main shaft is bent and this is why you're having trouble removing it.

You might need to remove the bottom gyro plate, and use a small punch to tap out the main shaft, or loosen up both main shaft bearing blocks, split the frame and remove the whole main shaft assembly so you can tap the shaft out of the blocks and get the main gear assembly off.

If ANY bearings are NOTCHY whether you pre-load them or not, replace them! Don't just assume that that is ok, a NOTCHY bearings is a BAD bearing. Also, I'd replace the bearings in the main shaft bearing blocks since it's obvious they endured the forces involved in bending the main shaft.

If you don't replace notchy bearings, they will wear our faster, start producing metal debris, and things will not operate smoothly.

As far as the odds, check all of the bearings in the rotor head and main shaft assembly, and I'd also look at the bearings in the tail just to make sure they're ok. Anything is possible and the only way to rule stuff out is to physically check it.

good luck!

- Dan Goldstein
Team Revolectrix

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02-15-2011 03:10 PM  6 years agoPost 3
BOB WHO?

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Downey, Ca.

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Thanks Dan. Yes the main shaft is slightly bent. So I take it that that the main shaft will normally just slide out once the cap bolt (though the pulley/maingear assembly) is removed? I will inspect all bearings once I disassemble. Since I have not ever taken the blade grips off or apart I wasn't sure it if could be something besides the bearings that make both grips feel a little sticky when turning them with no side load (centrifugal). It doesn't seem likely to me that all the bearings you mentioned should need to be replaced in a single minor crash. I've had plenty of crashes with other brands of poorer quality than Compass. BTW in relation to other mainstream brands what quality bearing are installed in Atom 500s?

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02-15-2011 03:22 PM  6 years agoPost 4
darkfa8

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Brick, NJ - USA

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normally, to remove the main shaft you need to:

1. remove the rotor head yoke
2. remove wash-out & swash plate
3. loosen set screw in main shaft collar that is under the top main bearing block
4. remove the jesus bolt that retains the second gear assembly from the main shaft

main shaft should slide out.

I don't know what brand bearings are in the model. However, a better quality brand of bearing (BOCA, SKF, or equiv.) is not going to necessarily survive crashes any better and don't really justify the costs unless you seldom ever crash. The better quality bearings typically have a longer service life.

Like I said earlier, it may not seem likely, but the sure way to know is to check. They might be bad, they might not. If they are notchy and/or have dented dust shields, they need to be replaced.

- Dan Goldstein
Team Revolectrix

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02-15-2011 04:50 PM  6 years agoPost 5
BOB WHO?

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Downey, Ca.

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Thanks again Dan. Yeah the head is off the shaft, the mast lock (collar)is loose, the only remaining cap bolt thru the main gear assembly is out. So the main shaft bearings must be binding on the shaft. I'll check all bearings too. I haven't seen this type of dampener before so I figured (hopefully) that maybe the stickiness I feel rotating the blade grips might have something to do with them. But as stated already when a load simulating centrifugal force is applied the blade grips rotate freely.

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02-15-2011 06:28 PM  6 years agoPost 6
darkfa8

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Brick, NJ - USA

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in most cases, as I've never seen something contrary in the 30 or so models I've worked on, when you rotate the main grips by hand, the spindle and thereby the dampers in the yoke seldom rotate UNLESS there is some sort of binding in the bearings, bent spindle or bearing(s) binding.

Usually the resistance of the dampers on the spindle keep it from rotating much, if at all on the bench if turning a grip by hand.

If you're going to check the bearings in the main grips by pulling them off the spindle, while you're at that point, you should check the condition of the dampers. Since they're rather small rubber o-rings, it's good piece of mind to just make sure they're not damaged as a result of the impact.

let us know what you find!

- Dan Goldstein
Team Revolectrix

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02-16-2011 06:15 AM  6 years agoPost 7
BOB WHO?

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Downey, Ca.

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Well the main shaft is out, finally. I've never had the kind of trouble removing a shaft as I did with this model. The main shaft bearings were pretty well stuck on the shaft after the crash. This solid steel shaft is not plated or polished and the surface might actually be softer than other main shafts. The bearings appear to be fine by the way. Now I'm on to the blade grips and the catchiness or stickiness I'm feeling. I'll report back.

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02-19-2011 04:25 PM  6 years agoPost 8
BOB WHO?

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Downey, Ca.

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The spindle was just slightly bent and was replaced so the notchy feeling is gone. The blade grips rotate freely but not the smoothest action I've felt. The bearings in the grips seem good and were not replaced. One of the arms that bolts onto the blade grips was bent and twisted. I removed, put it in a vice and gently tapped it into shape. I am re-using that part. I also straightened a mixing arm and am re-using it. The head is completely repaired and ready to go. I also replaced a tail blade grip that was damaged. Now on to the servo gears (9650s) that were stripped on all cyclic servos. I've ordered the MKS replacement metal gears and will replace all of them. I understand that the stock arms are a tough fit on the metal replacement output gear. Any ideas or experience with that?

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02-19-2011 04:52 PM  6 years agoPost 9
darkfa8

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Brick, NJ - USA

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it's not really wise to re-bend aluminum parts back into shape, it tends to just make them even more weak - this isn't like auto body work

as for the MKS gears, I have their 9670 and 9660 servos and yes, the arms do fit on rather tight and not with the precision feel that real Futaba servo gears have. Just be careful when installing the arms to be sure they're aligned and press them on until full seated. Then use just a small bit of medium strength thread lock on the servo arm screws and you'll be all set.

- Dan Goldstein
Team Revolectrix

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02-19-2011 05:43 PM  6 years agoPost 10
BOB WHO?

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Downey, Ca.

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Thanks Dan
I forgot to ask about the servo screw arm screws; do you know if the stock screws work on the metal output gear? By the way when if comes to straightening or replacing I have a slightly different view at the solution than you. When it comes to rotating shafts, they get replaced if they're bent; period. But when it comes to other bent parts I look at each problem on a 'one by one' basis. I have experience as a hobby welder and blacksmith and have basic knowledge on working with steel and aluminum. If a straight aluminum part is bent 30-40 degrees or more in a crash, I'll replace it. If is is bent less than 20 degrees I'll probably try to bend it back. I'll put it in a vise, apply some heat and be very gentle when I move it back. Of course I'll inspect the metal for cracks under magnification and replace anything that looks suspect. I've never once had a failure of a part that I straightened but have tossed out many bent parts.

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02-19-2011 10:00 PM  6 years agoPost 11
darkfa8

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Brick, NJ - USA

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Bob,

On the aluminum straightening, whatever you feel comfortable with.

On the output shaft screws, the metal gears use a fine thread machine screw.

- Dan Goldstein
Team Revolectrix

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02-19-2011 11:37 PM  6 years agoPost 12
BOB WHO?

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Downey, Ca.

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Thanks Dan
After just ordering the gears from Hobbyking, I found a local hobby shop with the gears in stock (pleasant surprise). I bought them today and the 'fine thread machine screws' too. Guess I'll have extra gears when the HK package arrives. I also got a full-size tail servo,JR8900G, off an ebay seller because the model I got came with a mini (9257). Wouldn't you know; the 'new' servo came in an opened package. That kind of stuff makes me cringe, don't know what I'll do about the transaction. What's the Futaba full-size tail servo model number?

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02-19-2011 11:50 PM  6 years agoPost 13
darkfa8

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Brick, NJ - USA

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the most popular Futaba tail servo is the BLS-251, otherwise, the S9254.

- Dan Goldstein
Team Revolectrix

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