Author Topic: E-max motor construction (Read 1964 times)

Paul Allen · « **on:** August 18, 2011, 01:52:01 AM »

Guy's
Can anyone tell me how the round can section with the magnets
attaches to the end housing, the end of the ball driver is pointing to the area
in question.

Igor Burger · « **Reply #1 on:** August 18, 2011, 02:00:55 AM »

I do not have emax motor, but typical construction for outrunners of this type is steel O ring, or better tube (that part with letters etc) over the alu rotor (fron of the motor) on its alu magnets separators (tepmpleats) ... something like round ridge

Tim Wescott · « **Reply #2 on:** August 18, 2011, 09:35:35 AM »

It pretty much has to be pressed, shrunk, or threaded, possibly backed up by glue. What are you trying to do that you need to know?

Russell Bond · « **Reply #3 on:** August 18, 2011, 04:19:50 PM »

On this motor there is a little grub screw that you loosen and then the shaft will slide for you to adjust the endplay.

Tim Wescott · « **Reply #4 on:** August 18, 2011, 08:59:34 PM »

Quote from: Russell Bond on August 18, 2011, 04:19:50 PM

On this motor there is a little grub screw that you loosen and then the shaft will slide for you to adjust the endplay.

I don't think he wants to know how the housing attaches to the shaft, but rather how the housing is assembled. Which kind of implies that he's fixing to take the thing apart, or perhaps to try to put it back together...

Paul Allen · « **Reply #5 on:** August 19, 2011, 04:16:42 AM »

Tim
My mate had a prop strike before take off, with this E-max 2832 motor, after which
he had a vibration and something was rubbing.After telling me this over the phone we
thought it may have bent the shaft so a new one was ordered,last weekend while
visiting with him we stripped the motor to change the shaft,but the old shaft was straight.
So I brought it home and put the parts in the lathe to check for running true and roundness
of the can, what had happened was the can section had walked off the end plate in one spot
not by much and this gave the impression that the shaft was bent.I set it up in the lathe and
pressed it back square hence the question on how it was attached when made?
Paul

Igor Burger · « **Reply #6 on:** August 19, 2011, 05:11:25 AM »

I do not think it is good idea to repare it home, those long rotors need dynamic ballancing.

Tim Wescott · « **Reply #7 on:** August 19, 2011, 10:25:59 AM »

Paul: Clearly then it is either pressed or shrunk on. I'm voting for pressed, as I doubt that if it were shrunk on that it would have been so likely to get pranged, nor that you could just press it back together on your lathe.

Igor has a good point, not because the balance should be checked, but because a prang like this might permanently stretch the end of the sleeve a bit, making the press fit too loose to stay in place.

Igor: If he put things back together where they were then both the static and dynamic balance would be OK. If the motor company is a good one then it may still be a good thing to send it in for repair -- they would know whether or not it could just be pressed back together or whether it would need to be tossed.

Paul: if you have a lathe, maybe you should investigate making a dynamic balancer for these guys...

Igor Burger · « **Reply #8 on:** August 19, 2011, 10:43:36 AM »

It could be back properly, it it could be also bent somehow, the experience says, that rotors need to be replaced after some hours of usage, because they are out of balance, so if this happened, it will be probably out of balance too. Problem is not vibrating like unbalanced prop, problem is that the bell can resonate itself, and it starts abruptly and damage could be immediate (free magnets, stalled motor, damaged ESC) ... I know, black colors, and relatively low proability, but the motor is not so expensive components to risk it :- ))))

But try it, play with it, exprience is necessary, you will see what you can and what not, just be carefull if you want really fly. I would not use it in real plan for real flying.

Tim Wescott · « **Reply #9 on:** August 19, 2011, 12:29:44 PM »

I have four inclinations that would go to war with each other if it were my motor:

One would be to just press it back together and go fly. This is because I'm a lazy cheapskate.

Two would be to take it all the way apart, then reassemble it either with aluminum solder or really good epoxy (not hobby shop stuff). This is because I break stuff by being a lazy cheapskate. For the epoxy I'd either check machine tool suppliers for a metal-specific glue, or I'd use JB Weld (which is metal specific, but comes from the bottom of the metal-specific barrel). For the aluminum solder (which doesn't contain solder, by the way -- it's usually some mix of white metals with some really aggressive flux that's what makes it actually work). This effort would include making sure that there's room for the glue or solder to do its job, so there'd be some rework involved.

Three would be to machine a new bell. This is because I like building stuff, not because I'm smart.

Four would be to take it as an opportunity to completely take the motor apart, to find out how these things are put together. This is because I'm just that way. I'd put all the bits in a plastic bag and promise myself that I'd reassembly it "later", and that it'd be "better".

Russell Bond · « **Reply #10 on:** August 19, 2011, 05:25:04 PM »

I wouldn't spend too much time trying to fix one of these motors as they are only US$30 at himodel.com.
(Unless you are like me and want to see how things work by pulling them apart.)

(By the way, they are the same as Arrowind.)

http://www.himodel.com/electric/EMAX_960KV_Outrunner_Brushless_Motor_for_2_to_4kg_Airplane_Type_BL2832.html

Paul Allen · « **Reply #11 on:** August 20, 2011, 04:29:09 AM »

Guy's
All good replies,I suspect that the unit is pressed together and also think the fit now, may be too loose
so I will check with the owner and if OK, will disassemble it so I know how it goes together because inquiring
minds need to know.
Paul

Paul Allen · « **Reply #12 on:** August 21, 2011, 08:16:11 PM »

OK
Here is how it attaches,very light press fit,fingers go between magnets.
Paul

Russell Bond · « **Reply #13 on:** August 21, 2011, 09:00:38 PM »

Oooooow,
No wonder the can flexes in hard maneuvers on these motors, that's why I went to Plettys as they have the can supported by a third bearing.
I went through a number of Arrowinds which are the same as Emax as the can would flex, the magnets would then scrape and from then on the motor was noisy.

When these motors are running well they are great, however it would have been cheaper for me to buy one Pletty than all the Arrowinds that I bought.

Paul Allen · « **Reply #14 on:** August 22, 2011, 01:17:08 AM »

One other thing,the info on the motor advertises it has 3 bearings,
there are only 2.

Tim Wescott · « **Reply #15 on:** August 22, 2011, 09:08:21 AM »

Quote from: paul allen on August 21, 2011, 08:16:11 PM

Here is how it attaches,very light press fit,fingers go between magnets.

That does look like it might fix right up with some epoxy that's specifically made for gluing metal, or some Loctite bearing glue.

Or it'll just seem that way, until it lets go in the air...

Crist Rigotti · « **Reply #16 on:** August 22, 2011, 10:44:27 AM »

Quote from: paul allen on August 22, 2011, 01:17:08 AM

One other thing,the info on the motor advertises it has 3 bearings,
there are only 2.

My guess is that there were 3 bearings used at one time. 2 smaller bearings were used at the top of the post. Since been replaced with 1 larger bearing.

Paul Allen · « **Reply #17 on:** August 22, 2011, 02:28:20 PM »

Tim
Yes, Loctite Retaining Compound.

Crist
You could be right,Scorpion do it that way.

Dean Pappas · « **Reply #18 on:** August 22, 2011, 09:14:44 PM »

Hi All,
Yes, but that's not what I generally mean when I refer to a "3-bearing" motor.
The third bearing (if there is one) is the circumferential bearing at the open end of the bell.
Of course, it won't be open any more!

So far, it's just the Plettys and the 40 and up sized Hackers.

take care, All
Dean

Crist Rigotti · « **Reply #19 on:** August 22, 2011, 09:30:23 PM »

Quote from: Dean Pappas on August 22, 2011, 09:14:44 PM

Hi All,
Yes, but that's not what I generally mean when I refer to a "3-bearing" motor.
The third bearing (if there is one) is the circumferential bearing at the open end of the bell.
Of course, it won't be open any more!

So far, it's just the Plettys and the 40 and up sized Hackers.

take care, All
Dean

Right.

Paul Allen · « **Reply #20 on:** September 12, 2011, 03:51:53 PM »

Motor is back together and has had a 6min run on the test stand, all good.

Tim Wescott · « **Reply #21 on:** September 12, 2011, 04:05:35 PM »

Before you put it into service you may want to challenge the repair. I'd get it running at speed and rotate it through 90 degrees about as fast as you'd expect a square corner to take. This would be easy for me, because my test stand is mounted to a chair -- I'm not sure if that would work for you.

Make sure it still works when you're forcing some in-flight forces on it...