Different Size Cutter Key Ways

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gwarner

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I recently acquired a horizontal mill. I have been trying to increase my selection of cutters by buying lots of cutters from e-bay. While I did get several arbors with my mill, the majority of arbors are 1 inch with a quarter inch key way slot.

The cutters I have been buying all have a one inch hole and the majority use the ¼ inch key but there are a few that have a 5/16 inch keyway. Needless to say this presents a problem.

What is the best way to use the cutters with a 5/16 key on my arbors with ¼ inch keyway? Should I mill the outer edges of a ¼ key to make it fit 5/16 or cut a slot in a ¼ inch key to fit a 5/16 key. Thus using 2 keys ? Or is there another solution that I have not thought of?
 
I would cut a 5/16 key to fit the 1/4 key way. Either one edge, or a little from both edges, I doubt the end result would matter either way. The 2 key idea, sounds like more trouble then it is worth. Keys are cheap, play around, and learn.
 
I may be wrong but you could set the cutter against the key in the direction it runs and use it that way.
 
Cutting a step key is probably the best solution. Don't attempt to re-cut an arbor to a larger size keyway. First, the arbors should be hardened, so it will be tough going, Second, the arbor will probably warp when you change the keyway size.
 
what's with this "buying" crap? :face slap: hit the key with a file/grinder for a little bit and make one! probably be done before your computer finishes booting up.

:)
 
I figured there had to be something like the step keys and that was what I pictured milling out. Thanks for the feedback. Will a few out tonight.
 
I use a horizontal mill to cut key seats in marine grade SS boat shafts. 3/6" to 1" keys. And never use a key in the cutters. Friction hold just fine.
 
Bob Korves said:
.............. First, the arbors should be hardened, so it will be tough going, Second, the arbor will probably warp when you change the keyway size.
Click to expand...
You don't want use a harden arbor. But you don't want one that is soft either. To me a harden arbor would be one that tested in the high 50's or low 60's on the Rockwell scale. That's too hard. You want it in the 32-42 HRC range. All the one's I've ever used or been around were in this hardness range. Now the spacers and running bushings are harden to 58-62 HRC and you want that. I do agree not to widen or deepen a existing keyway. It more than likely will warp and have a bow shape that you never be able to straighten completely out. Make you a step key as other have said. Last, make the key long enough to extend out about an inch on both sides of the cutter. Hum, that's not going to work with a cutter with a different size keyway in it. I have run cutters with larger keyways in them with standard keyways in the arbor with no problems.
 
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