600w BMC Dead? Help

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BillWalendy   1 mW

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600w BMC Dead? Help

Post by BillWalendy » Mar 05 2010 11:44am

I have a one year old 600W BMC hub that has been a pain in the ass every now and then. Well now is a now and this time I think it might be terminal. I have a video and will be trying to figure out how to post it but in the mean time I can describe the symptoms. I have been having some "slipping" for some time. Usually I can release the throttle and sync up the motor and wheel rpm's. This has worked quite a few times in the past. This time not so much. The sound is very loud and rhythmic. On or off battery the sound is the same. I have the hub disassembled. Sound appears to be coming from the magnets. Can I continue to disassemble and clean or am I just screwed. Please help!!!

Video http://www.youtube.com/watch?v=K0NSLXaM_Jw

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Re: 600w BMC Dead? Help

Post by nicobie » Mar 05 2010 1:48pm

I think you need to get the whole assembly out so you can check the planetary gear/sprag clutch assembly. That is what usually goes bad.
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Re: 600w BMC Dead? Help

Post by BillWalendy » Mar 05 2010 3:07pm

OK so I am trying to get deeper into this hub and have come to an stall. How do I get this off?
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BillWalendy   1 mW

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Re: 600w BMC Dead? Help

Post by BillWalendy » Mar 05 2010 4:14pm

I have the planetary gears off and they are fine. Now I am trying to get the rest of the assembly torn apart. I am considering going to the parts store for a gear puller. I just wish someone with some knowledge could say yeah or nay.

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Re: 600w BMC Dead? Help

Post by amberwolf » Mar 05 2010 4:50pm

If I understand correctly, you're trying to get the rotor (magnet ring) off (or to say another way, to get the stator out of the rotor, off the axle)?

Mine is a Fusin geared but they are both similar in construction; just need to know exactly what you're trying to do.

Where exactly is the problem--is it in the planetary (which has the freewheel/clutch) or is it in the rotor/stator?

EDIT: Based on the YT vid it sounds as if it is in the magnets, with one rubbing on the stator, but you don't say whether the problem went away once you pulled the motor out of the hub housing. If it did not, then it is in the magnets most likely, perhaps one of them has come unglued or a piece of something is stuck in there between the stator and rotor.

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Re: 600w BMC Dead? Help

Post by BillWalendy » Mar 05 2010 5:43pm

I am still getting the noise and rotational friction but it is not a bad as it was before disassembly. I am not sure what I need to do so I continue to disassemble and clean/inspect then reassemble until I fix the issue. I cant seem to disassemble any further now so I am asking for some direction.

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Re: 600w BMC Dead? Help

Post by amberwolf » Mar 05 2010 5:55pm

At this point it's going to depend on whether the stator (with the windings) and the rotor (with the magnets) are secured to the axle in a way that requires a puller, or if they are slipped together and the only thing holding them together is the force of the magnets.

If the former, it is possible to damage the motor if not careful in doing the pulling or if the puller doesn't fit right or catch on the right places (or if the motor parts are not strong enough to pull against in those places).

If the latter, it's simply a matter of pulling hard enough to get the rotor/stator away from each other without crushing your fingers between them. ;)

Before you do any of that, though, take a nice bright light, preferably while you're out in sunlight, and look down in between the rotor and stator to see if any of the magnets look displaced, or if there is any debris between the magnets and the outer diameter of the laminations, stuck in the air gap.

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Re: 600w BMC Dead? Help

Post by BillWalendy » Mar 06 2010 1:37pm

I rented a puller from taylor rental and pulled the shinny thing from the electric part :D Bit scarry but think it went well. So I found some filings and one loose magnet. I think all I need to do is re glue it and put everything back together. Question is what to use for glue. Pics follow.
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Re: 600w BMC Dead? Help

Post by nicobie » Mar 06 2010 2:10pm

You did good getting the magnet cup off. I hope you marked where it was positioned on the axle. If you are lucky it will go back square on and not wobble, otherwise you will need a lathe to square things up.

Can't help on what type of glue to use, but I'd think hi-temp epoxy will be fine. Don't use the 5 minute type as it doesn't hold as well as the slow setting stuff.

You might also check if the magnet is still good. If it got too hot it might have failed.
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BillWalendy   1 mW

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Re: 600w BMC Dead? Help

Post by BillWalendy » Mar 06 2010 2:29pm

Well two things. First thing. I thought about marking just after I got it off and dont have a lathe. Second thing. How can I check if it got to hot?

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Re: 600w BMC Dead? Help

Post by BillWalendy » Mar 06 2010 2:32pm

That might not be relevant any more it just broken into three pieces. Shit. Where does one buy replacement magnets.

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Re: 600w BMC Dead? Help

Post by itselectric » Mar 06 2010 11:36pm

BillWalendy wrote:Question is what to use for glue. Pics follow.
If you ask DoctorBass, he will tell you the best glue for magnets is:
3M Scotchweld DP460 epoxy

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Re: 600w BMC Dead? Help

Post by itselectric » Mar 06 2010 11:59pm

BillWalendy wrote:That might not be relevant any more it just broken into three pieces. Shit. Where does one buy replacement magnets.
Bill, I just got your email. Let me check in the store, and see what i have. If you don't hear from me 2 days, just email me again.

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Re: 600w BMC Dead? Help

Post by dnmun » Mar 07 2010 12:32am

you have to make sure the polarity is reversed sequentially when you put a replacement magnet back in place. they have to go north south north south, etc so that the hall sensor is toggled properly. you may be able to put the pieces in place in the epoxy but you have to make a jig that will keep the pieces in place when set.

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Re: 600w BMC Dead? Help

Post by BillWalendy » Mar 07 2010 11:12am

I'm starting to wonder if I should just, if I can buy one, replace the rotor. Who would I buy that from? :?
Last edited by BillWalendy on Mar 07 2010 10:21pm, edited 1 time in total.

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Re: 600w BMC Dead? Help

Post by dnmun » Mar 07 2010 2:34pm

why can't you glue it back in with epoxy? someone just mentioned on another thread some super duper epoxy. i always use J-B Weld since i always have some.

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Re: 600w BMC Dead? Help

Post by Doctorbass » Mar 07 2010 2:55pm

dnmun wrote:why can't you glue it back in with epoxy? someone just mentioned on another thread some super duper epoxy. i always use J-B Weld since i always have some.

His magnet is broaken in 3 seperate pieces he said. When magnet seperate, they modify their polarity and all seperated parts become repulsive to each others.. it's impossible to recover.

As i suggested him, these BMC magnets are very small and are easy to find replacements on ebay... or using old hard drive disk magnets that you just rework using a drewmel or other grinding tools and cool the cuting job with water to avoid them overheat and loose their magnetism. I already did that and it work fine!

Many windturbine DIY man build their motor using HD magnets and it work nice!

The key for a best glue job is to CLEAN perfectly both pieces before to them glue together using acetone and then alcool..... or just alcool.

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Re: 600w BMC Dead? Help

Post by karma » Mar 07 2010 3:47pm

don't forget to sand the area on the ring where your going to place the magnet than clean it with acetone or alcohol.

use a fine grit :wink:

smooth steel and glue don't mix :|

if it was me i would re glue all the magnets.

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Re: 600w BMC Dead? Help

Post by mwkeefer » Mar 07 2010 7:02pm

karma wrote: if it was me i would re glue all the magnets.
+1 on the reglue all the magnets... look at some of the RC motor builds and magnet replacements / repairs on the forum, then use their technique... fill the space between the magnets with hitemp epoxy and don;t use too much just enough to fill the gaps a bit - if some of the epoxy ends up above the surface level of the magnets then use some fine grit to bring them down.

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Re: 600w BMC Dead? Help

Post by 999zip999 » Mar 08 2010 2:55pm

Good thread on the BMC. Have you been climbing hills ? What is your controller. ? How many amps. ?

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Re: 600w BMC Dead? Help

Post by BillWalendy » Mar 08 2010 7:49pm

I am a recovering alcoholic. August 5 2007 was my last drink and/or drug. I lost my license for OUI 2. Its been 4 years with out a license. ( I have never been in an automobile accident or hurt another person while drinking). I have a disease called a vascular necrosis of the hips due to my years of excessive drinking. I can not peddle a bike anymore and I need to get to school. I have returned to college and am in a Nuclear Medicine Technologist program. Straight A's thank you. 51.2volt 10ah 35amp controller on a Kona Dr. Dew with 700c wheels, hayes hydrolic disk brakes, and planet bike fenders I have been able to get around pretty good.

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Re: 600w BMC Dead? Help

Post by BillWalendy » Mar 08 2010 9:04pm

Did you hear it? The loud popping sound. I got both feet up to my butt and pulled my head out.

https://www.kjmagnetics.com/proddetail.asp?prod=BC82

Look like the right thing? I cant believe it was advertised at the bottom of the page and I didn't see it for two days.

Adhesive and nickel coated moly magnets are ordered. Less than $30. Thats affordable. I am worried about north-south poles. How do I know which way I need to put it in or will that become obvious. And what about getting the rotor positioned properly? Will I really need a lath?

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Re: 600w BMC Dead? Help

Post by 999zip999 » Mar 09 2010 3:46pm

My 40amp. crstalyte with 600BMC makes a noise if I go more than 2/3 to 3/4 throttle the yellow light will flash and I do not push at all. Did your 35amp. controller frist sing then haaaaaaaa with a virbration if push hard . I'm going to turn mine down to 30amp.

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Re: 600w BMC Dead? Help

Post by 999zip999 » Mar 09 2010 4:08pm

Sorry I'm 53 and new to computers. I ment to ask you did your hub make the haaaaaaaaaa noise and vibartion with 35amp. controller. ? Is this noise and vibration the reason or is it the heat that cause the problem with the magnets ? I have a BMC and to replace my gear reduction after my frist 2mos. BMC sent me a new one that looks much stronger. But i wish I replaced the C- clip with a new one. Good luck.

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Re: 600w BMC Dead? Help

Post by BillWalendy » Mar 09 2010 5:11pm

I don't know what the haaa noise is. My issue was a bit more dramatic. I have gone threw a maybe 6-8 controllers. They have a tendency to blow. But good luck

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