BM16 with loose magnets - how to fix?

[Nova's Ark]

I have a BM16 brushless outrunner that I installed in my 2.2 crawler. I have been running a 1000KV crawlmaster and wanted to try a BM16 to see if the drag brake would be stronger. Everything worked perfect before with the crawlmaster.

I installed the BM16 and started experiencing loss of control and minor glitching. I swapped it out for the crawlmaster and everything was perfect again. So I disassembled the BM16 and found two loose magnets inside.

- Are the loose magnets the cause of the problem?

- Is the motor repairable?

- What can I use to reattach the magnets?


Everything else looks great inside the motor. Thanks in advance for any help.

[666]

I have pulled magnets off my Revolvers and had no luck getting them to stay back on using epoxy or glue.

I bet that is your problem, my Mamba 25 fried due to loose magnets.

Be careful, I hear that the magnets are toxic.

[666]

Check this:

Dead OG Revolver

[EGRESSor]

Originally Posted by Nova's Ark

I have a BM16 brushless outrunner that I installed in my 2.2 crawler. I have been running a 1000KV crawlmaster and wanted to try a BM16 to see if the drag brake would be stronger. Everything worked perfect before with the crawlmaster.

I installed the BM16 and started experiencing loss of control and minor glitching. I swapped it out for the crawlmaster and everything was perfect again. So I disassembled the BM16 and found two loose magnets inside.

- Are the loose magnets the cause of the problem?

- Is the motor repairable?

- What can I use to reattach the magnets?


Everything else looks great inside the motor. Thanks in advance for any help.

http://www.gismosindustrial.com/Prod...?sku=442-21447
works great

[Nova's Ark]

666 you are such a great Moderator!!! Thank you so much for the quick replies and information. That is extremely helpful.

[EGRESSor]

Originally Posted by 666

I have pulled magnets off my Revolvers and had no luck getting them to stay back on using epoxy or glue.

I bet that is your problem, my Mamba 25 fried due to loose magnets.

Be careful, I hear that the magnets are toxic.

http://www.powercroco.de/Magneteinbau.html

[666]

Originally Posted by EGRESSor

http://www.powercroco.de/Magneteinbau.html

Engrish?

[666]

Originally Posted by Nova's Ark

666 you are such a great Moderator!!! Thank you so much for the quick replies and information. That is extremely helpful.

Thanks, your the only one who think that though.

[Nova's Ark]

Originally Posted by EGRESSor

http://www.powercroco.de/Magneteinbau.html

Thanks for the link. I don't read German though:-(, so I used babelfish.yahoo.com to translate it and here is what it looks like in English.

[EGRESSor]

http://66.196.80.202/babelfish/trans...paraturen.html
some more about outrunner repair

[HBRC]

You can get adhesive at an autoparts store, i think it's sold as rear view mirror glue.

Check out gobrushless, or customCDR.com. they both sell kits to build your own brushless motors. They should have info on what glue to use.

I've used the rearview mirror stuff on a couple of motors that I've built.

You only have to be carefull with the rare earth magnets if you sand or break them. if your just glueing them in, no big worries. wear some gloves and a mask if yer scared.

[EeePee]

Originally Posted by 666

Thanks, your the only one who think that though.

Totally.

[Narly1]

On the subject of toxicity, I just did a wiki search on Samarium Cobalt and Neodynium, two common magnetic compounds.

Neither was listed as toxic.

Narly1

[antikas]

Originally Posted by Narly1

On the subject of toxicity, I just did a wiki search on Samarium Cobalt and Neodynium, two common magnetic compounds.

Neither was listed as toxic.

Narly1

http://en.wikipedia.org/wiki/Neodymium#Precautions
http://en.wikipedia.org/wiki/Cobalt#Precautions

[EGRESSor]

NdFeB and SmCo are alloys , you will not seperate the single elments by grinding or other mechanical impact

both are as toxic as stainless steel

[Nova's Ark]

Upon closer inspection of the BM16 brushless motor last night, half the magnets are unglued. That makes a total of eight magnets that are loose. Thankfully the magnets have a red mark on them denoting north and south poles, but I have a few more questions.

- Does there need to be any spacing between the magnets?

- If I re-glue the magnets, will it perform properly?

In the thread that 666 linked to, it sounded as though RXcrawler's revolver never performed the same once the magnets were re-glued. Is there anything more to this that I need to be aware of? I don't want to waste time and money on a motor that will not perform properly once repaired.

- Would just the loose magnets alone cause the glitch and loss of control?

[JohnRobHolmes]

In order of your question-

Yes, the spacing is important. Use matchsticks or whatever you can find that makes it even.

If you reglue them properly it will perform just fine

Loose magnets cause all kinds of problems, including glitching of the motor. Loss of control may be a radio issue.

[Nova's Ark]

Originally Posted by JohnRobHolmes

In order of your question-

Yes, the spacing is important. Use matchsticks or whatever you can find that makes it even.

If you reglue them properly it will perform just fine

Loose magnets cause all kinds of problems, including glitching of the motor. Loss of control may be a radio issue.

Thank you JRH I had been waiting for you to respond. The magnet spacing on the BM16 is extremely narrow, like .5 mm or so. It almost looks like they are all touching. Can the magnets touch each other?

In regards to my radio, My electronic specs on the crawler in question are this;
- DX6
- AR6000
- Mamba Max
- CC BEC
- Thunder Power 3S lipo
- Hitec 5955 TG steering servo
- Hitec 645 MG dig servo

Everything was flawless with the 1000kv CrawlMaster. The problems started with the BM16. I rebound the DX6 just be sure I didn't have a radio issue. The problems continued, so I removed the BM16, re-installed the crawlmaster and everything was normal. That is when I disassembled the BM16 and found the loose magnets.

[Nova's Ark]

Just to update the thread, I re-glued the magnets on the BM16 using Loctite 380 . I used the Loctite 380 to glue the magnets in place. Once the 380 glue had cured, I used medium CA glue to fill in the gaps between the magnets and further help to secure them. I have run two battery packs through the motor and it works properly.

The BM16 along with the other electronics draw some serious power though. My small 3S lipos cannot keep up with the power needs as the battery drains. My Thunder Power 1320MAH 3S 20C lipos will last 15 minutes or so before any problems arise. Once the pack is 2/3rds run down, the receiver will shut down when the truck is bound up. The 1300 Viserlo 3S 15C lipo won't even last a few minutes.

What is interesting is that the Holmes CrawlMaster 1000KV (same KV as the BM16) has no issues what so ever with either battery pack and works properly until the voltage cut off. The drag brake is not as strong as the BM16 and that is the only noticeable difference. I will probably end up installing the BM16's (I have two of them) into my clod super where I am using Max Amp 3S lipos in much larger MAh capacity. Thank you for the links, information and help. I don't think I would have repaired the motor properly with you guys.