12v DC motors from china

[kiwi_al]

I took a punt on a small batch of small 12 volt DC motors from china for the princely sum of $1.43 USD and just $0.99 cents for postage. They arrived today 4 out of the five work fine and 1 was DOA. That's not bad, I guess I now have to pick one and put it through a torture test. [ Guests cannot view attachments ]
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[narrowminded]

I took a punt on a small batch of small 12 volt DC motors from china for the princely sum of $1.43 USD and just $0.99 cents for postage. They arrived today 4 out of the five work fine and 1 was DOA. That's not bad, I guess I now have to pick one and put it through a torture test. (Attachment Link)
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Don't scrap the dead one.  Try applying 12 volts to the leads and then poking a wire through the brush retainer hole to add a light force to the brush.  Some of them have a skin of oxide on the commutators and this will break through that oxide.  Once running they'll clean themselves up, pretty much immediately. 

I suspect they saw some less than optimum storage conditions and part of why they're available on Ebay but once you get a few revolutions on them they run flawlessly.  At least that's what I found.  You could probably spray the commutator with some contact cleaner or even CRC 2-26 lube.  Then lightly oil the end bearings and they're ready for service.

[kiwi_al]

Don't scrap the dead one.  Try applying 12 volts to the leads and then poking a wire through the brush retainer hole to add a light force to the brush.  Some of them have a skin of oxide on the commutators and this will break through that oxide.  Once running they'll clean themselves up, pretty much immediately. 

I suspect they saw some less than optimum storage conditions and part of why they're available on Ebay but once you get a few revolutions on them they run flawlessly.  At least that's what I found.  You could probably spray the commutator with some contact cleaner or even CRC 2-26 lube.  Then lightly oil the end bearings and they're ready for service.

Yep I looked at doing that and applied low power for a short time to the commutator and the motor spun. I did carefully take it apart (yes I can get it back together) and found they had not installed the brushes!!! Airgap. Must be some new fangled technology

[narrowminded]

Yep I looked at doing that and applied low power for a short time to the commutator and the motor spun. I did carefully take it apart (yes I can get it back together) and found they had not installed the brushes!!! Airgap. Must be some new fangled technology

Yup.  Apparently there's more to brushless motors than simply removing the brushes.

[MK]

Curious as to how <long> it took to get to you in a pandemic.  I do realize you are down under and much closer to China than we are in the states.  But still...

[kiwi_al]

Curious as to how it took to get to you in a pandemic.  I do realize you are down under and much closer to China than we are in the states.  But still...

This was quite quick,  it was entered into the chinese postal system on the 23rd November and arrived today the 12 December. I was quite surprised. It actually got to NZ on the 5th December which was far quicker than I thought.

[peteski]

There are lots of those types of motors on eBay for a buck or two a piece.  We have discussed these I think last year.   The black ones, and the gray ones. I have also found several other types (like the larger ones used in Life-Like E-units) and ones similar to what was used in Walthers 0-8-0.

We speculated that these are either from a production line that closed, or possible rejects (but still usable).

Remember that if the listing has the "best offer" option, use it. Epsecially if you sre buying larger quantity.  If your offer is reasonable, the seller will accept it, and you will save some money too.