Motor Magnets Loose (SZ4926-510)

[McCollister911]

If a magnet come loose on one of your hv setups what would you do? I bought this from a fellow freak so original receipt is not a possibility i wouldn't think. I did research a little on building/winding and seen what types of glue they used (hi-temt epoxy, loktite 638?, and jb weld) all i had here was a little JB so i mixed it up, scuffed the magnet and can, applied a thin layer to both and stuck em back together. air gap looks perfect and poles are correct. Will this thing vibrate like crazy if i do fly it, depending on the state its in when i wake up. Motor is still apart letting it cure overnight. any input is appreciated, and i know i should just buy another motor but i really wanted to try this one out.

[ragge1]

I wouldn't , think goona be out of balance
buy here : http://www.nankinhobby.com/product-p/08-4927.htm

[Rob43]

I's get in contact with Nankin Hobby to see if they can honor it as a warranty item. It's a recently made motor.

Give them a shot. But understand that this week, things are a little crazy. I happen to know Mike is closing on a new home Monday, and the whole crew is heading to IRCHA Tuesday.

[kimmik]

I'd do exactly what you did, DIY fix. Money could solve anything but the satisfaction from your own work is priceless.

Here's how I'd test it.
Spin it on bench to full revs to test for resonances
Spin up with blades at the field and do some big collective maneuvers (start light work up). Then it's proven.

I haven't used jb but if it's resilient like epoxy, temp resistant, and you cleaned/scuffed/aligned well then no foreseeable issues.

[Rob43]

Might be successful, but if there is vibration, how to correct? I would think that placing the magnet on the witness mark which indicates it's original position should be close enough. Some risk, though, as I wonder if the other magnets are also properly attached. I'd still suggest having it replaced by Compass.

[McCollister911]

Magnet is down tight. Not going anywhere. What I notice now is spinning by hand it feels much tighter. When I got the moor it was much more loose feeling. Maybe when I got it the magnet was already loose and therefore made the field less effective. Now it's in the right place it's definately tighter. Does this sound right

[Rob43]

Sorry - no experience with that. I'd suggest testing it with the pinion back off and snugged into position so you can safely test programming and motor operation.

[Raynman]

Yes that sounds rite, I had a magnet come loose - felt loose when spinning by hand, I expoxyed it BK in and strait away it was a much tighter feel when spinning - I have had over 50 flights with no issues at all.

[McCollister911]

How tight are the 4926 motors you guys have compared to a simalar sized scorpion or quantum. And compare it to a 450mx/500mx. Because mine feels like a 450 motor. I'm not sure enough to fly it. Seemed to get hot MUCH faster on the bench since my fix

[Rob43]

Unless I misunderstand by what you mean when you refer to "tighter", but by comparison to my Pyro 700 and Align 700MX, my 4926 feels like it has greater magnetic pole resistance to turning. More so also than compared to the Scorpion 4035-560 I used to own. I still suggest sending it back. As I stated earlier, no telling if all the magnets are firmly bonded. If one was loose, perhaps others could be too. Would represent some risk to the ESC, I am afraid. I could be wrong, but with ESC's, we don't want to risk an in-flight failure.

[McCollister911]

That's exactly what I was saying about the tight feeling. It's magnetic resistance when I got it was a lot less than it is now. I have compared it to 2 45xx series and several 40xx's. All those felt much easier. And yes I have made my mind up on the issue to send it in. The esc was my concern as well. I'm hoping they will honor the warranty since it was bought from a fellow member here and I don't have the reciept. The motor had once been one of the original models I'm guessing with excessive glue and was refurbished. Think it was doomed from day 1

[kimmik]

Was there a chance you reinserted the magnet reversed? That would explain the difference.

[McCollister911]

pretty sure i had it right but yes theres defiantly that chance and i think thats what happened

[McCollister911]

Well Mike at Nankin cross shipped me a replacement rotor can under warranty It's installed and yesterday it got a good break in of about 10 flights. The new can felt much better in terms of the resistance, felt normal so I must have glued that magnet in reverse (idiot!). The new can has a different finish (still nickel but not polished, old can was mirrorlike) and Mike said it was the 3rd generation if I'm not mistaken (1st=excess epoxy 2nd=loose magnets) which he also said there haven't been any issues with to date that he is aware of. Motor did great! Running Vbar gov/YgE 120/2000-2400 HS on the goblin 630. The stator reached 118F max and outside of can 116F! Esc hit 121F. Outside temp was about 90. That's really low for what I'm used to seeing. I'll put it through some abuse in the next few weeks as I get a better feel of the new heli. So far I'm very pleased the outcome and I can't say enough about Nankin's customer service. I bought the motor from a fellow freak in the classifieds. He had it replaced because the epoxy issue. So I had no reciept, not a leg to stand on. Sent mike the email explaining the problem, hoping for a discout on replacing the rotor. He called and after we went over the history it ended up costing me $9 and that included an extra set of bearings. He shipped as soon as we hung up and as I promised him I shipped the defective part back the following day. Needless to say Nankin will have first shot at my money from now on. Thanks for all the replies.

[Mixmaster Pilot]

The Nankin guys are true class

Also good to hear that Compass has made some changes to the motor, it's taking some time, but they are actively working things out and providing great customer support