Putting a radius on corners of end mill

[homebrewed]

I've got a number of square-end end mills that have chipped corners. I'm planning to make an end mill sharpening jig similar to Harold Hall's but also want to extend the life of the end mills. I've read that rounding the corners of an end mill can extend their life, but I'm not sure how to do it and not screw up the cutting action. I also think it would be difficult to avoid a situation where only one of the flutes is cutting, if rounding by hand. Does anyone have any hints on how to do this?

 

[T Bredehoft]

I've done it freehand, but only with limited success. You have to make certain you not only round the corners equally, but relieve behind the cutting ledge, too.

 

[4ssss]

Stone them if they're not too bad

 

[Illinoyance]

I chamfered a bunch of endmills with chipped corners. Quicker than radiusing.

 

[benmychree]

Yes, chamfering is easier, have done radius by hand also; easy enough if it does not need to be accurate, and does not matter for most purposes if only one edge cuts.

 

[mmcmdl]

Your smallest radius will be the edge cutting the final size , but your other edges will also be cutting . Grind and then then stone or use a diamond file .

 

[homebrewed]

Sorry, but I'm not finding enough details here for me to get it done. Example: grinding a radius around what axis? Radially or axially? A blend? Chamfer? Sounds good, but similar questions. Apologies for being difficult, but I'm looking for specifics like orientation of the grinder/lapping/honing tool relative to the geometry of the EM. Now you know how little I know about end mills!

 

[4ssss]

Sorry, but I'm not finding enough details here for me to get it done. Example: grinding a radius around what axis? Radially or axially? A blend? Chamfer? Sounds good, but similar questions. Apologies for being difficult, but I'm looking for specifics like orientation of the grinder/lapping/honing tool relative to the geometry of the EM. Now you know how little I know about end mills!

Put a radius on the corner and put relief on the back side. It's not rocket geometry

 

[homebrewed]

I'll give it a shot after I build the grinding fixture. That way I can experiment to my heart's content.

Thanks!

 

[4ssss]

I'll give it a shot after I build the grinding fixture. That way I can experiment to my heart's content.

Thanks!

Why bother? Clamp the end mill in a vise and stone a radius on it.