How would you cut this radius?

[Jeff.64]

Use a boring head. Place a sacrificial piece of same thickness steel spaced around 2" from the work piece and center the head rotation between them. This will allow you the take measurements between them to get an accurate radius.
Or butt another piece of same thickness steel up to the work piece and use an annular cutter and then clean up with a boring head.
Or take it out back and wing each side with a toy howitzer.

 

[bill70j]

Rotary table. Multiple plunges with drill bit followed by end mill for clean up. One set up, minimal tool wear, and fewest chips.

 

[tq60]

If a good hole saw can cut the material, place in vise, slow as it can go and have at it with you mill.

Sent from my SM-G781V using Tapatalk

 

[Janderso]

My immediate thought is also a boring head. You can use a scrap piece of aluminum to cut a hole to fine-tune the radius if you need to.

BUT, to be silly: OFFset it significantly in a lathe, and cut it with a boring bar

I was thinking of putting it in the four jaw but the set up would be beyond me.
I like the idea, it’s easier I think. Adjusting the boring head after each pass would be finicky and take forever.

 

[mmcmdl]

I like the idea, it’s easier I think. Adjusting the boring head after each pass would be finicky and take forever.

Once you set the head it doesn't need to be adjusted . Just move over and feed down .

 

[Janderso]

To set a boring head to a known radius , pick up and edge and zero the read out . Move over the radius amount and bring the boring bar out until it rubs your original edge . Pretty simple .

Simple for you.

 

[mmcmdl]

Simple for you.

Jeff , it is simple . One set up .

 

[machPete99]

On the lathe...
Make a sacrificial piece the same width and drill/ream a hole to where the center of the arc would be.
put them in a 4-jaw and use the center hole to properly align, keeping the edges flush.

 

[Doug Gray]

Perfect job for a faceplate on the lathe.

 

[OTmachine]

Perfect job for a faceplate on the lathe.

Setup time? And a lot of thumping on a little lathe.