How Are Slotted Keyways Squared Off?

uncle harry said:
While not likely a hobby machine it can be don by EDM (Electric discharge machine)
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I think they should be. A simple one is easy to build and mine has got me out of a few scrapes pretty quickly.
I used the transformer from an old welder that output 40 V
There are heaps of plans online that a quick search will pop up, Mikes is simple and clean http://mikesworkshop.weebly.com/a-spark-erosion-apparatus.html
Mine is a lash up and not suitable for public scrutiny.
 
I think there is a difference between can this be done and should it.
I have seen both types of key way. From the end of the shaft the radius end and within the shaft, round end slots.
In both cases the rounded shapes reduce the stress at the key way. Creating the square corners increases the stresses.
 
I agree: rounded or "swooped" keyway ends are stronger,and best left as is. The OP's question was just theoretical.
 
Considering the last two posts, is/was there a point to 'squaring the end of a key-way'? Or was it a cosmetic problem?
 
The OP was just curious as to how it could be done Tom.

"Billy G"
 
Franko said:
I can't imagine a client that would pay a machinist what it would take to cut such a slot, or any reason to cut one other than to show off...
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I know of one case where this was done in a production environment on old manual machines before EDMs were dreamed of. The RPD was the world's first squad automatic weapon. It was designed and built by the same team that built the AK47. Anyway, the bolt has flaps that seat into a square inside corner of the receiver. I don't know how they did it with WWII surplus machinery.

https://en.wikipedia.org/wiki/RPD_machine_gun
 
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John Hasler said:
EDM was invented in Russia in 1943...
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Hmm, maybe that's what they did. I'm surprised. I always want to think of the commies as not as good as us. But realistically, their weapons manufacturer was excellent with great design.
 
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