My motor shaft broke!

[Aces]

Hello. I know this topic is about my motor but it is from my Roban 700 Apache build. So I’m hoping to get a little help. I installed several upgrade parts in my mechanics including a new main belt. I put it all back together and test ran it on the bench. After about 30 to 45 seconds the shaft on the motor broke. I’m going to assume that I tightened the belt too tight. I have the aligne 800 MX 520 KV motor. So I have a couple of questions.
1. Does anyone know if the shaft can be replaced on this motor? If so is there an instructional video somewhere that someone can link to? I’ve searched on YouTube and can’t find one specific to this motor.
2. Secondly, in general, is this motor OK for this build? If I have to purchase another motor what would be the suggestions?
thanks.

[PawPaw]

Aces....how did the top of that motor can get scored like that?

[Aces]

Hi PawPaw. Honestly I’m not sure. I picked up this motor used from a friend. But I don’t recall if it had those on there at the time. I do know that the motor was rubbing against the air inlets that I custom built in the canopy of this Apache. But those are made out of paper so I don’t think that caused the scarring. It must’ve come like that. But it’s been several years so I don’t remember. It’s been performing fine up to this point.

[DCORSAIR]

Wow, never seen one do that before, that shaft had to have some type of damage or something before you put it in I would think, I don't think having the belt to tight would have done that but I could be wrong, I have two Align 700KV motors, one in my Roban Apache and one in my Roban OH-6, I would like to know what caused that for sure, seeing that is making me nervous, I run my belts a little loose now after watching the guy from Scaleflying.de adjust his, how tight would you say yours was Ace??

Also, those shafts are hard to find right now, to take it apart, you need to loosen the set screws hidden in the cooling fan vent holes, then once they are out you can punch out the shaft, I just set the motor upright and use a punch and hammer and tap it out, or use a press of some sort, if you take the two set screws out, make sure you catch them some how or they will jump over to the motor magnets and cause problems, I stuff a small part of a paper towel in the hole to let the set screw fall on it or magnetize an allen wrench.

[Aces]

Hello DC. I guess it’s kind of hard to explain how tight it was. If I used one finger to press against the belt I had to push really hard to get any deflection. Unfortunately, after the fact, I was talking with my dad about the incident and he said that he had felt the belt and it seemed really tight to him. But he didn’t really question it since it’s not his machine. he did explain to me that because the belt and The pinion both have teeth that the belt does not need to be as tight as a friction belt would be.
unfortunately I just don’t think we will know the answer but I am going to go with the theory that it was too tight.
and you were right, after doing a ton of looking around I was able to find a shaft in the UK. Got it headed my way. And thank you for the advice on how to get the shaft apart. I was finally able to find a video on a 500 MX which appears to be the same motor just smaller.

[sfcfury]

I know on my Cobra, my initial setup I had the belt tension too tight, and it pulled and it made the top plastic gear rub on the metal belt drive gear. You should actually be able to push the belt in about a 1/4 inch, and/or twist the built almost a 1/4 inch. Here's video (in german-turn the auto translate/subtitles on) that illustrates the tension very well.
Still tho, for the motor shaft to break... wow.

https://www.youtube.com/watch?v=iEqE7KebqmY

[DCORSAIR]

Hello DC. I guess it’s kind of hard to explain how tight it was. If I used one finger to press against the belt I had to push really hard to get any deflection. Unfortunately, after the fact, I was talking with my dad about the incident and he said that he had felt the belt and it seemed really tight to him. But he didn’t really question it since it’s not his machine. he did explain to me that because the belt and The pinion both have teeth that the belt does not need to be as tight as a friction belt would be.
unfortunately I just don’t think we will know the answer but I am going to go with the theory that it was too tight.
and you were right, after doing a ton of looking around I was able to find a shaft in the UK. Got it headed my way. And thank you for the advice on how to get the shaft apart. I was finally able to find a video on a 500 MX which appears to be the same motor just smaller.

Little trick when you get the new shaft, mark the end of the shaft where the flat spots are, this way when you put the new one in you know where to line it up, here is my Align motor that just got a new shaft right before they all sold out, you can see the silver marks on it.

[Aces]

Thank you fury for that information. I will take a look at that video.
and thanks Corsair for that idea. Will definately do. I will let you guys know how it goes once I have the shaft. That’s going to be a few weeks probably so don’t hold your breath.

[DCORSAIR]

Thank you fury for that information. I will take a look at that video.
and thanks Corsair for that idea. Will definately do. I will let you guys know how it goes once I have the shaft. That’s going to be a few weeks probably so don’t hold your breath.

Well, if you need a motor to use for now, I would be more than happy to send you this one to get you flying, it's 750-530kv but it will drop right in, might be a little high KV but will work, you can send it back afterwards or if you like it just keep it, all free of course.

[co_rotorhead]

Might find this one useful as well:

https://www.youtube.com/watch?v=7ppBk1zGsRE

[DCORSAIR]

Might find this one useful as well:

https://www.youtube.com/watch?v=7ppBk1zGsRE

Thanks for the video link, I have watched him before but not that one on belt tension, he has lots of experience.

[co_rotorhead]

Thanks for the video link, I have watched him before but not that one on belt tension, he has lots of experience.

You should make the drive up to Washington for the scale heli event July 15-18 and meet the man himself (and me) 😀

[Herman Munster]

Too tight of a belt shouldn't break a motor shaft, those are hardened steel, you're going to damage your bearings before a shaft breaks.

[DCORSAIR]

Too tight of a belt shouldn't break a motor shaft, those are hardened steel, you're going to damage your bearings before a shaft breaks.

Yeah, I said the same thing, if you look at his picture it looks like the shaft was cracked already to me anyway.