Getting a radius'd edge. Calling all experts

[Lou Anderson]

I'm cutting cylindrical pieces of wood on my Sherline CNC lathe (i need hundreds of them). The part i'm having a hard time figuring out is the best way to get a 2mm radius'd edge - see illustration below.



In the picture you can see the red lathe tool which i'm having a hard time making from HSS blanks (can't get that nice 2mm radius).

Does anyone have suggestions on how i may be able to do this better?

Edit: I should clarify that wood 'bushing' is there so i can cut through it to get my 2mm radius without cutting into the mandrel.

[davereagan]

You can buy that tool made of solid carbide for $37.00. It's made by Micro 100, is double ended, has three flutes and has a 1/4" shank with a minor diameter of .060". Page 204 at www.kbctools.com part #CRE250080

[Lou Anderson]

Originally Posted by davereagan You can buy that tool made of solid carbide for $37.00. It's made by Micro 100, is double ended, has three flutes and has a 1/4" shank with a minor diameter of .060". Page 204 at www.kbctools.com part #CRE250080

Thanks for the suggestion. That tool can't be used in the lathe though could it?

[davereagan]

I went right over the word "lathe". I'm sorry. I doubt the tool would work for a lathe. I'd look around for lathe tooling. If you held only one part and positioned the tool with the correct rotation, maybe you could cut on the left side with it. If you look at p.239 in the same catalog, you'll see some radius cutting bits toward the bottom of the page. The closest they come is 1/16 or 3/32", but you could modify them.

[LeeWay]

It shouldn't be that difficult to grind this. For wood, you will want a pretty good undercut. Leave only the crisp sharp cutting edge touching the wood.
It looks like these will be machined wooden pens and pencils.
If so and you have a cnc lathe, then just a simple cutoff tool with steep undercut would do this. It would do the entire turning actually.

Otherwise, you could make such a tool that would hold sandpaper in this shape. Have a few that would be different grits.
Lots of handwork that way though. Never good for lots of parts.

[Lou Anderson]

Originally Posted by LeeWay It shouldn't be that difficult to grind this. For wood, you will want a pretty good undercut. Leave only the crisp sharp cutting edge touching the wood. It looks like these will be machined wooden pens and pencils. If so and you have a cnc lathe, then just a simple cutoff tool with steep undercut would do this. It would do the entire turning actually. Otherwise, you could make such a tool that would hold sandpaper in this shape. Have a few that would be different grits. Lots of handwork that way though. Never good for lots of parts.

Thanks for the feedback LeeWay. I'm a newb when it comes to some of these terms. What exactly do you mean when you say a cutoff tool with a steep undercut?

[LeeWay]

This is the type tools I use. A steeper angle would be more than 10 degrees. I think this is what angle mine come at. I do cut mine a bit sharper on one end for brass. You would want a bit more i think for wood. You want it very sharp with no rubbing underneath.

[Cruiser]

There are some people here with EDM machines and just maybe one of them can program and cut one for you just as you need. Only make it out of a vanadium cobalt blank, It will last much longer.