How to mill a slot without a mill?

[B2]

I would make a broach and broach it in the lathe.

I agree. i.e. google "Youtube broaching on a lathe" or

 

[Orangetruckman]

I'm still going to make a pitch to the finance chairwoman for a mini mill

Sometimes it has worked out better to buy and ask for forgiveness later. I recently got secondhand mill/drill that way I haven’t gotten the mill setup or even plugged in yet but wouldn’t mind paying it forward and helping with things like that in the future. I’m about 30 minutes from the couve.
Nice job tackling that with the drill press.

 

[dml66]

Sometimes it has worked out better to buy and ask for forgiveness later. I recently got secondhand mill/drill that way I haven’t gotten the mill setup or even plugged in yet but wouldn’t mind paying it forward and helping with things like that in the future. I’m about 30 minutes from the couve.
Nice job tackling that with the drill press.

That's very kind of you to offer, I may take you up on that someday .

 

[Parlo]

I agree. i.e. google "Youtube broaching on a lathe" or

Or on a mill?

 

[rwdenney]

For those recommending broaching, take a look at the part the OP is duplicating. The keyway is in the middle of a shaft and closed on both ends. I’m thinking that’s gonna be tough using broaching approaches.

Rick “the slot has already been machined in a drill press, as I recall” Denney

 

[RaisedByWolves]

For those recommending broaching, take a look at the part the OP is duplicating. The keyway is in the middle of a shaft and closed on both ends. I’m thinking that’s gonna be tough using broaching approaches.

Rick “the slot has already been machined in a drill press, as I recall” Denney

Sure, but does it need to be?

Many ways around this particular problem.