Sharpening endmills.

[th62]

This is how I sharpen end mills. I have a cheap, Ozito rotary tool for which I made a couple of tool post holders. One for the rotary tool, the other for the extension, both are adjustable.
I have marks on the chuck backing plate and a pointer for indexing, although, mostly I just do it by eye.
The stone was a little course, but it works OK. I'd run out of fine stones, so just used what was handy.
I start off by chucking the end mill and grinding the end of the end mill flat, then using a different stone, I grind a dimple in the middle. you can either run the lathe or turn the chuck by hand, although running the lathe wears out the stones rather quickly.
Next, I adjust the rotary tool to give a good cutting angle and grind each cutting edge. Once done, I ensure the dimple in the middle reaches out to,the inner cutting edge, if not, I just grind the dimple a little wider.
This was done on a four flute, for aluminium, I use two flutes. Four flutes tend to gunk up.
I don't regrind the flute edges as that affects the diameter of the end mill.
As you can see in the last pic, even using a very course wheel the finish is decent.
This is how I sharpen end mills, I'm not suggesting it will suit you, but it suits me, gives good results and saves on end mills and a big outlay for a T&C grinder. If you don't like, simple scroll past.

 

[markba633csi]

Ever do center-cutting endmills by that method? I imagine it would be possible if you were careful

 

[toprecyler]

Thanks for sharing. I will sharpen end mills at work by hand, if necessary to finish a job. I may not do as good of a job as factory, but I can get it good enough to do the job necessary.

I will sometimes actually change the way I mill, in order to preserve the end mill side flutes. If I’m making a long slot, I would prefer to plunge cut the slot, moving the end mill generally .100” DOC, to the desired depth. This way I am only removing the material using the end of the end mill. Which is the easiest for me to sharpen by hand, or setting up on surface grinder if I choose to do a little better job. I sometimes will do an undersized end mill this way, and then will move the table each way to finish the sides. By doing it this way, the side flutes do not remove all the material, so endmills will last longer.

Of course, I realize that since I work on manual machines, 9 times out of 10, the reason I may need to get a new end mill, or replace a carbide insert, will be to a human error. It’s not because the tool actually wore out due to cutting to much. I accidentally moved the tool too quickly into the cut, didn’t keep feed consistent, had RPMs too fast or slow, etc.

My hard part is realizing in my job, that sometimes it is more profitable for the company to just change that insert, or have them purchase a new end mill, vs the time it take me to sharpen what I have. In my home shop, I have to justify the money I spend, so I can be as frugal as I want and resharpen my own tools.

Sometimes, we may find we have more time than money to fund our hobbies. There is nothing wrong with doing every thing we can to do things for our selves. It make us better machinist over all, if we understand the cutter geometry needed, and the ways we can achieve that in our own shops, if we so desire.


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[MrWhoopee]

My hard part is realizing in my job, that sometimes it is more profitable for the company to just change that insert, or have them purchase a new end mill, vs the time it take me to sharpen what I have. In my home shop, I have to justify the money I spend, so I can be as frugal as I want and resharpen my own tools.

Sometimes, we may find we have more time than money to fund our hobbies. There is nothing wrong with doing every thing we can to do things for our selves. It make us better machinist over all, if we understand the cutter geometry needed, and the ways we can achieve that in our own shops, if we so desire.

Having been both a job shop owner and a hobbyist, this is one of the big differences. Time is money in a commercial shop, it's free in a hobby shop. In fact, anything that prolongs my time in the shop simply increases my pleasure. My wife likes it too.

 

[Boswell]

Well said @MrWhoopee