How would you cut this radius?

[Janderso]

Hey all,
I’m making a squareness comparator.
The material is O1 tool steel.
The radius of the two side cutouts are 1 1/2”.

Just looking fir ideas on how to do it.
Thanks,
Jeff

 

[twhite]

If you have a boring head you could do that. I have cut larger radii with ball mills using a formula. Unfortunately that is at work. I can get it for you on Tuesday.

Also if you have a small fly cutter you can set the diameter and use that to bore.

Or a rotary table. I assume you do not have that hence the post.

Those are a few off the top of my head.


Cutting oil is my blood.

 

[ErichKeane]

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

 

[benmychree]

I think that I'd use the boring head.

 

[RJSakowski]

Or for sake of completeness, a CNC.

As I recall, the side cutouts are esthetic and as such not super critical as to location, and size. They could be roughed out with a bandsaw and finished to final shape with a carbide burr and/or small diameter grinding wheel. You might even find a wheel of appropriate dimensions to suit your radius. If you have a woodworking shop, the drum on a belt sander stationary belt sander is near your radius. I have an oscillating drum sander that would work for final finishing. Filing to shape with a rat-tailed or half round file can satisfying although it can lead to blisters.

 

[buffdan]

Or hog out with bi-metal hole saw, cleanup after

 

[mmcmdl]

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 .

 

[OTmachine]

radius of tool divided by radius to be generated = sine of angle of mill head cant

 

[cross thread]

I have done that with a fly cutter . I wouldn't want to make my boring head do that interrupted cut .

 

[extropic]

Clamp the workpiece to a face plate on the lathe.
Fence it in, as required to be super secure.
Add some stock, opposite, to approximate acceptable balance.