Re: [CAD_CAM_EDM_DRO] Frozen stepper motor shaft

In a message dated 1/21/2006 10:18:36 A.M. Central Standard Time,
menglish@... writes:

Of the three I can only turn the shaft of one when not connected to any
power. On the other two, the shafts will not turn. Does anyone know if these are
junk or is there a way to free up the shafts?



Make sure the lead-wires are not shorted together! Then, try to turn again.
If the wires were not shorted, then it may be swarf inside the motor,
jamming between the stator and armature, or bad bearings. I found that NEW
Unipolar Superior Electric steppers have only SHIELDED, not sealed bearings, so
find swarf can READILY "get IN there" and jamb-up the bearings! I admit I do
NOT know if the KML- series, bipolar "square" motors have sealed bearings, but
I would BET not!

Now if you find these are still jammed after making sure the wires are
electrically separated, the only way to "fix" these motors is to dismantle.
HOWEVER! Without the "factory jigs" to insure the armature comes out
PERFECTLY-AXIALLY so it does not contact the stator, FORGET about it! (unless you don't
care about sacrificing these motors). I had the bearings in a SE unipolar
motor jamb up with dust, and the only way to replace with proper bearings was
to dismantle the motor. It was useless anyway, so why not? I did, installed
new proper bearings, and put it together again, using a paper tube over the
armature to prevent contact upon re-entry. The motor worked, but had
NOTICEABLY less torque after that!

Sadly, messing with steppers without factory-fixtures is a no-no!
Jan Rowland


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