Cutting keyway on motor shaft

J

Justin King

Joined
Nov 8, 2009
Messages
1,533
Anyone tried cutting a slot for a key on a motor shaft with a dremel or angle grinder, or other "poor man's tool"? I have a few motors laying about without keyways on the shafts, I'm not sure how to put them to use.
 
I have done it using a dremel before. First, I scribed a line for the slot, center punched and drilled to remove the majority of the steel. Then I just stacked the little abrasive wheels on the dremel until it was wide enough for the slot. Kind of like a mini dado blade. It worked really well. Hope this helps.

-Mike
 
Keyways are just one way of driving a shaft.

You could just use a set screw / grub screw partially drilled into the motor shaft to align the pulley and motor shaft.

or

From the end of the shaft, you could drill a hole with the centreline on the border between shaft and pulley and install a dowel pin in the hole.

Or drill the same hole above and use a safe edged file to square up the corners for your key.
 
Better yet find a local machinist. They will probably do it for $20. Used to cut key seats all the time. Easy if you have a mill.
 
I've done it with a flexible shaft rotary tool (Dremel's have similar functionality). I roughed out the cut with a small (1" diameter) cut off wheel. Then used a small (1 or 1.25" dia) grinding wheel attachment to clean up. The little abrasive wheel's thickness was just under the the desired width of the groove. I may have used a small square file as part of the clean up process too, but can't remember. It all worked out just fine though.
 
Do you have a 4.5" grinder or a end grinder and arbor? If so you can get disk in 1/6 3/32 1/8 3/16 and 1/4 widths. If you wanted a 3/16 slot I would use a 1/8 disk to get it close then finish with a new 3/16.
 
I appreciate the input, guys. I have an angle grinder, dremel, and square files so I think I will manage.
I picked up 5 industrial motors from the scrap metal pile at the local landfill, apparently a tool/equipment repair shop had closed and thrown away over a dozen motors of various sizes. I tested 3 of the 5 and they worked, I gave away 2 and still have 3. Now I just need 3 machines to put them on...
 
If working with those tools in that way is kind of new to you, you could always practice on a steel rod of similar diameter.
 
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