testing bipolar stepper motors from ebay

[cowanrg]

i just bought some steppers off ebay and one of them has a really stiff shaft (yeah, thats what i said, get over it ). two of them turn freely with my hand, but the other one doesnt turn unless i use a wrench of something to turn it. it does seem to turn ok, but it takes some effort.

is there an easy way to test the motor? i was even thinking about buying a cheap bipolar driver:

http://store.qkits.com/moreinfo.cfm/QK158

eventually i plan to get geckos, but just not right now. can i just connect power to one phase to get it to step once, or do i have to have a controller?

[Halfnutz]

Ive heard that a battery will work, but Ive never done it myself. I do know that the motors should turn with slight resistance by hand and cog slightly. Anything other than that means trouble. Ive bought a number of steppers off ebay and have had a couple that were junk. They were siezed, like what your describing. They would turn a half a revolution or so and then get stuck. Fortunately I didnt pay much ( 6.50 for three) and just trashed them.

[PEU]

be sure to have all the motor wires isolated and try again, if they touch together that may be the problem. It happened to me


Pablo

[cowanrg]

Halfnutz,

these are actually the ones that you linked to, the superiors, KML092's. i got em for pretty cheap.

ill check to make sure the wires arent touching. i guess i can try activating a single coil with a battery to see if it even budges. he did say he would send a replacement though.

[Halfnutz]

The ones I got from him were brand new. Thats cool that he will replace it. Send it back if your in doubt. Steppers can go bad if they get wet or even high humidity can cause them to oxidize inside and sieze. I'm glad he said he'd replace it, since I posted the link. Those are some nice motors, theyre worth at least 100.00 each, as long as they work.

[cowanrg]

yeah, he did state that they were new and working, so its a good thing he offering to replace them.

however, mine dont exactly look new... the metal is kinda discolored and looks old. this could just be the metal oxidising over time or whatever, but its not how "new" should look. i can take pics if anyone is curious.

but, as long as they work ok, thats fine with me.