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  #1  
Old Tue 29 June 2010, 12:03
kanankeban
Just call me: Hector #89
 
Monterrey
Mexico
Grinding flat spots on shaft for set screw seating

Hi...
Finally I found some place to buy my spur gears, I have to choices with key way and setscrew for $26 or plain bore which ill have to drill and tap the holes. My question is if I really need the keyway does it works with the oriental geared motor?
Thanks...
Hector
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  #2  
Old Tue 29 June 2010, 12:49
smreish
Just call me: Sean - #5, 28, 58 and others
 
Orlando, Florida
United States of America
No keyway is neeeded. But 2 (two) set screws are needed - placed 90 degrees opposed to each other.
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  #3  
Old Wed 30 June 2010, 14:22
domino11
Just call me: Heath
 
Cornwall, Ontario
Canada
Sean,
Did you grind the second flat on your steppers? Any suggestions if you did or warnings? I am kind of worried of that procedure when it become necessary.
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  #4  
Old Thu 01 July 2010, 05:17
jhiggins7
Just call me: John #26
 
Hebron, Ohio
United States of America
Heath,

I ground the second flat on the axles. I too was worried, but Gerald's very strong advice to have TWO set screws overcame my fear. It was really simple, using a hand-held, 4.5" grinder, being careful to hold the shaft at 90 degrees to the pre-ground flat.
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  #5  
Old Thu 01 July 2010, 07:44
J.R. Hatcher
Just call me: J.R. #4
 
Wilmington, North Carolina
United States of America
Send a message via Skype™ to J.R. Hatcher
Why not use the skate in the "rail cut down mode" adjusted to the right height. Set the stepper on a flat surface then turn the shaft with the existing flat vertical, put current to the stepper to lock it up and grind the second flat??
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  #6  
Old Thu 01 July 2010, 10:30
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
Put stepper shaft horizontally in vice, with one flat against a jaw, grind or file a flat on top.
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  #7  
Old Thu 01 July 2010, 13:19
smreish
Just call me: Sean - #5, 28, 58 and others
 
Orlando, Florida
United States of America
Gerald,
I did just that. Placed motor shaft in vice with plastic to protect the faces, then used a large flat mill file to put a flat on the shaft. I took away the bulk of the flat with a grinder first, then mill file. But those who aren't careful should start with a file. It doesn't take long!
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  #8  
Old Thu 01 July 2010, 16:30
bradm
Just call me: Brad #10
 
Somerville(MA)
United States of America
I picked up a suggestion on another site: Place a little molding clay or the like around the shaft where it enters the motor to prevent any metal filings from migrating toward the magnets via the bearings during the operation.
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  #9  
Old Fri 02 July 2010, 00:33
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
Brad, that good suggestion raises an interesting subject.......

The shaft of a stepper motor is supposedly made of non-magnetic stainless steel, thus the filings shouldn't be attractive to the magnets. I don't know if this is true for all stepper motors, but I did see it on the OM motors. However, the OM motor shafts already have 2 flats, but their gearboxes only have one (strangely,considering the torque levels). The gearbox shafts are probably magnetic, but some distance from the magnets.

It still stays a good suggestion to seal up the bearings before metal particles and grindwheel dust are generated around there.

The awareness of the stainless steel shaft explains why the pinions sometimes gall to the shaft when you try to pull them off. Especially if a grubscrew had been driven onto an un-flattened shaft before - the screw makes a lump on the shaft and the pinion doesn't like sliding over the lump. I bought some used steppers from ShopBot years ago and the state of the shafts were shocking, mainly because monkeys had tightened the screws onto un-flattened parts of the shaft. (that experience of SB's quality control is what started my change of thinking toward them)
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