Author Topic: Magic pie 3 play!  (Read 7289 times)

Offline Enpro

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Magic pie 3 play!
« on: March 11, 2012, 11:06:15 PM »
And its getting worse by the minute :-[.
Is there a way to adjust or tightening the mp3's axle/bearings?

Offline Henry Chang

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Re: Magic Pie III play!
« Reply #1 on: March 12, 2012, 02:05:28 PM »
I think that's not bearing don't hold tight, if Magic Pie gets worse, may be bearing quality to have a problem, or assembly motor grinding to coil .Then motor rotation, the coil is also constantly damage.

Offline Morgen 3Eman

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Re: Magic Pie III play!
« Reply #2 on: March 12, 2012, 08:20:13 PM »
Henry, could you post a photo of the bearings on the axle so we can see what holds them in place? 

Thanks,
Dennis

Offline Henry Chang

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Re: Magic Pie III play!
« Reply #3 on: March 13, 2012, 10:05:13 AM »
  Hi, Dennis, ok, I now after the work, and tomorrow I will go  back to take a photo. I hope I can help you .

Offline Morgen 3Eman

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Re: Magic Pie III play!
« Reply #4 on: March 13, 2012, 06:10:55 PM »
Thank you , Henry.  It is so much easier to understand and solve a problem when you can see how it is put together.

Dennis



Offline Bikemad

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Re: Magic Pie III play!
« Reply #5 on: March 14, 2012, 03:32:52 AM »
Is there a way to adjust or tightening the mp3's axle/bearings?

Unfortunately the bearings are not adjustable, as they are simply held in position on either side of the stator by the two side covers.
Here are some photos of my MPIII's bearings:

The left hand bearing has an unusually large inside diameter (85mm) to allow it to fit over the outside of the stator's tubular extension piece that houses the speed controller.


The right hand bearing is the same size as the earlier Pies, and it appears to have some form of locking compound holding it firmly inside the housing:

The inside of the bearing fits nicely over the machined surface of the axle next to the circlip:


I think the most likely place for any play to occur will be between the inside of the large bearing and the cylindrical part of the stator, but you will probably have to remove the disc brake mounting/fan assembly in order to see it more clearly.

Any play developing between the bearing and the stator assembly would result in movement as indicated by A and B on this photo of an early Magic Pie:


Alan
 
« Last Edit: July 04, 2017, 08:34:27 PM by Bikemad »

Offline Morgen 3Eman

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Re: Magic Pie III play!
« Reply #6 on: March 14, 2012, 04:14:10 AM »
Hi Alan,

Thanks for the photos, it makes it much easier to understand how it is assembled.. Enpro, which way is the movement you are seeing? A, B, C? 

So  are we to understand the stator is held in place on the axle by a square key for rotation and a snap ring for lateral position?   It looks like the large diameter bearing is located by two snap rings.   Is the smaller bearing also held in place by snap rings?  If one of the snap rings were dislodged, a movement in C would be pretty likely.....


TTFN,
Dennis

Offline Henry Chang

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Re: Magic Pie III play!
« Reply #7 on: March 14, 2012, 12:30:56 PM »
Hello Dennis,

Alan gave photos is that I want to give you, but he do it more clearly more understandable, Allen is a professional player, and to the improvement of the MP3 from MP, have been Alan's  advice, so he knows a lot.

Sorry for my English and I don't see snap rings what mean? I know the ball bearings with mp3 is, the smaller and large bearing are held in position on either side of the stator by the two side covers.

One of the snap ring were dislodged ?I was too stupid, sorry.....
                                                                       

                                                                                                                                                                                     Henry

Offline Morgen 3Eman

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Re: Magic Pie III play!
« Reply #8 on: March 14, 2012, 05:03:09 PM »
Ni Hao, Henry

You are not stupid.  I know how hard it is to use a language that is not your own.  I commend you for your effort.

I am the stupid one, as I used the American slang word "snap ring" when I should have used the correct word "Circlip".  A Circlip is the "C" shaped ring shown in Alans close up photo of the axle and stator.  It has been my experience that if a circlip is  opened too wide during installation it will tend to slip out of the groove when pressure is applied.  Would that allow the bearings and cover to slide about on the axle?

Thanks,
Dennis

Offline Sanfrancisco

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Re: Magic Pie III play!
« Reply #9 on: March 15, 2012, 03:16:49 AM »
Interesting. I had a lateral movement of Magic Pie 3. I took all the covers apart and determined that the there was a the big bearing had a little gap with the stator. So I used the red thread lock between and it helped the wheel much to be more stable and not to wiggle.

However, now I am running into a different problem. the the coils rub a bit the magnets. Not sure how to fix it. 

Offline Henry Chang

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Re: Magic Pie III play!
« Reply #10 on: March 15, 2012, 01:32:03 PM »
A Circlip is the "C" shaped ring shown in Alans close up photo of the axle and stator.  It has been my experience that if a circlip is  opened too wide during installation it will tend to slip out of the groove when pressure is applied.  Would that allow the bearings and cover to slide about on the axle?


Hi, Dennis, Now I know that C, I can  understand .
As you said, you said the experience is correct, if a circlip is  opened too wide, that could allow the bearing and cover slide about on the axle.
In fact circlip is to block circle stuck iron core, prevent iron core out. what the size of circlip, according to the size of the axle to choose, if not standard, otherwise will grind to bearing or stuck motor of the iron core.



Offline Morgen 3Eman

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Re: Magic Pie III play!
« Reply #11 on: March 15, 2012, 04:59:47 PM »
Hey, San...  It sounds like the movement you are experiencing is "B" in Alan's photo, rather than "C", and that the thread locker closed the gap, but didn't centralize the bearing on the stator. 

So here is a couple of ways to improve the centering:

You can use shim stock (thin metal sheet) to fill the gap.  this is the most common method.  In its simplest form, you can use aluminum foil to do the job.  Super glue the end of a strip of foil to the stator, and wrap the stator with enough layers to do the job.   As you wrap the foil around the stator, keep putting a small amount of super glue onto the foil to bond the layers together.  The foil will be too soft without the glue.  If you use too much super glue, it may not set up.

You can use thin wire wrapped in a spiral around the stator.  Again, use super glue  or epoxy to hold the wire in place.  (yeah, I like glue)   The advantage to using wire is there are gaps in the surface which allows you to deform the wire shape to make the pieces fit better.  You can even gently sand the wire down. 

You can use a center punch to make a series of divots in the stator.  The metal displaced by the punch will raise the surface at the edge of the punch, and effective increase the diameter of the stator.  This works pretty well on aluminum.  You want to distribute the divots evenly around the diameter, and form a band across the where the bearing will sit.   If you have an adjustable center punch, you can start out at a soft setting to make the pattern , and keep increasing the force at each divot in the pattern until you get a good fit.

Even layers of paint or tape can be used to build up the surface diameter in a fairly uniform manner. 

You'll need patience, too.

Dennis






Offline Sanfrancisco

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Re: Magic Pie III play!
« Reply #12 on: March 16, 2012, 12:13:26 AM »
Thank you Dennis,
This is really helpful. Indeed the movements I had were in the direction of B in Alan's picture. I will give your suggestions a try. It also was possible that during the opening process I destroyed the rotational symmetric of the pie a bit.
I see that the magnets are glued to the black steel rim. I wonder if they were rubbed by the stationary parts (coils) if they could potentially fall off.
Somewhere I read that a front pie ones locked due to a loose magnet. It worries me if that could happen at 30 miles an hour.