Milling a curved slot in 3/8 steel bar.

RB72

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All. I am working on a taper attachment and need to mill a slightly curved slot on each end of the plate the guide bar will be resting on in order to adjust the amount of taper. I don't have a rotary table, etc. Not sure the best way to accomplish that. I would prefer not making a wide straight slot and having to use washers to keep things from pulling through, etc. I am doing this on a mini mill machine.

Any suggestions on how I can do that?
 
Figure out the coordinates to plunge a end mill on the curve(like a bolt pattern) and then file the high spots down. The more locations you use the less there is to file.

PlungeCurve.jpg

PlungeCurve.jpg
 
That one I was aware of but was hoping someone had a more creative method involving less filing. Thanks for the reply.
 
Use the fulcrum hole in your plate as a pivot point to mill your curved slot. Layout and drill a hole in your plate to establish the fulcrum point. Then layout your radius slot and drill a hole slightly smaller than the finished width of your slot. With a softener under your plate bolt the plate and softener to your mill table so that the plate pivots with a slight amount of tension. The softener is so you can extend your end mill through the plate and not damage your table. Use and end mill of your choice and mill the slot by pivoting the plate by hand. You may want to clamp an extension to the plate to give your more leverage and control while milling. I've done this many time and it works real well.

Tom S
 
could you make a T slot cutter out of the proper radiused end mill? Grind all but the very tip leaving just under what you need. Just thinking out loud here
 
What would that accomplish? I'm not seeing it...:dunno:

could you make a T slot cutter out of the proper radiused end mill? Grind all but the very tip leaving just under what you need. Just thinking out loud here
 
With out a rotabor cnc, punching holes and file is about your only choice.
 
Use the fulcrum hole in your plate as a pivot point to mill your curved slot. Layout and drill a hole in your plate to establish the fulcrum point. Then layout your radius slot and drill a hole slightly smaller than the finished width of your slot. With a softener under your plate bolt the plate and softener to your mill table so that the plate pivots with a slight amount of tension. The softener is so you can extend your end mill through the plate and not damage your table. Use and end mill of your choice and mill the slot by pivoting the plate by hand. You may want to clamp an extension to the plate to give your more leverage and control while milling. I've done this many time and it works real well.

Tom S

+1. Given the equipment you have to work with, this is the way I would do it also.
 
Use the fulcrum hole in your plate as a pivot point to mill your curved slot. Layout and drill a hole in your plate to establish the fulcrum point. Then layout your radius slot and drill a hole slightly smaller than the finished width of your slot. With a softener under your plate bolt the plate and softener to your mill table so that the plate pivots with a slight amount of tension. The softener is so you can extend your end mill through the plate and not damage your table. Use and end mill of your choice and mill the slot by pivoting the plate by hand. You may want to clamp an extension to the plate to give your more leverage and control while milling. I've done this many time and it works real well.

Tom S

+2 :biggrin: This is pretty much how I did things before I finally got a rotary table. I will still do it if I get something bigger than my table can handle. BTW, take light cuts.

-Ron
 
Maybe I'm just misunderstanding what he wants. I am thinking of a rounded key slot. Half moon type. Which t slot cutter would create a half moon if plunged in on one side.
What would that accomplish? I'm not seeing it...:dunno:
 
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