Hand Sharpening End Mills- Can You Do It?

[ImanCarrot]

Can I sharpen a 1/2" end mill by just hand lapping it on a sharpening stone? (like those that you sharpen knives with) or is there some weird angle I need to put on it please?

Thanks.

[DareBee]

I will do anything when desperate.

It will be next to impossible to get it to cut effectively on all teeth, but what the hell, it needs sharpened anyway and you don't have a grinding fixture or the time to send it out.
Nothing to lose - right?

[ImanCarrot]

Cheers, worth a go then, it's now a 3 flute (was 4). My own bloody fault rapid move into the vise. How comes it always happens when you got the customer breathing down your neck lol.

[HuFlungDung]

Are you referring to shortening an endmill and resharpening? Yes.

Sharpening the outer helical flutes is a practical impossibility without a toothrest and some sort of bushing to hold the tool shank.

[ImanCarrot]

No, just the bottom of the endmill, it was a brand new endmill so the edge flutes should be ok.

I tried it and it wasn't perfect, but got the job done- ain't it always the way on a Friday afternoon!

[neilw20]

YouTube- PICT2812
I am using a more sophisticated setup now with dual wheels.
New setup refaces and gullets all in one setup. No videos yet - soon.
I redress 30 3 flute cutters at a time, taking about 0.2mm off the length.
I don't touch the flutes as I only damage 0.1mm of the cutter.

Dish angle so center of cutter does not rub is 1.8 degrees. The rotary table is inclined leaning towards machine column to achieve this.
Clearance angle is 4.5 degrees - notice the tilted spindle.
Typically cutters may be 8 degrees, but I use a lower angle so they last longer machining stainless steel, and I need a VERY sharp corner. My cutter life is 2-3 hours, and they are quite stuffed when finished with. Chipped, burnt. I actually get about an extra 15 minutes by a quick hand gullet with a diamond file. Does not noticeably affect the Z tool setting, because, even thought this shortens the cutter ever so slightly, the lower cutting load once filed stops my column bending as much - it stays within 2 microns!

Horrible job, but someone has to do it. (my Wife!) Most cutters have so far been redone about 10 times, which is better than forking out $25 every 2 hours.

With cheap rotary tables, you must have the cutter vertical, so that that the weight of the chuck does make the 4th axis sag/wobble.

This is not easy to do if you can't rotate the head to 4.5 degrees.
If you can't rotate the head, then you must tilt the 4th axis in 2 planes to get the 4.5 degrees and 1.8 degrees.

Also when rotating to a position, you must approach from the same direction so that backlash does not matter.

[HuFlungDung]

Originally Posted by ImanCarrot No, just the bottom of the endmill, it was a brand new endmill so the edge flutes should be ok. I tried it and it wasn't perfect, but got the job done- ain't it always the way on a Friday afternoon!

Don't the tool companies charge extra for vari-flute step cutting endmills? And to think you can make your own!

I cheat a little on the hand grinding: first I rough grind the primary clearance on all the flutes so it looks about right. Then lay the endmill in the corner of a good wide square and check to find which flute tip is touching. I only attempt to reduce gross errors, not fuss around, but one can very quickly get close. I always grind the end flutes with a 'hollow point' so that only the flute tips are my concern.

I have another wheel set up to gash the end flutes, basically removing the center area altogether. This also makes it possible to hold the endmill at such an angle as to get the wheel right in to grind a clean facet on each flute without running the other flutes onto the wheel.

Obviously, I will not attempt plunge cutting with a 4 flute (previously center cutting) with my resharps, but I can still ramp or helix with them, no problem.