# End mill grinder



## Stephen12 (Nov 27, 2012)

Hi All,
Thanks to the admins and members that keep this forum alive and informative.
My question is (not sure if someone has asked this before) I have 100's of end mills that I received but they are a bit worn and need regrinding. Has someone designed an end mill grinder that is simple enough to build so that I can regrind these end mills. I would hate to throw these away. 

Thanks
Stephen


----------



## cfellows (Nov 27, 2012)

Stephen12 said:


> Hi All,
> Thanks to the admins and members that keep this forum alive and informative.
> My question is (not sure if someone has asked this before) I have 100's of end mills that I received but they are a bit worn and need regrinding. Has someone designed an end mill grinder that is simple enough to build so that I can regrind these end mills. I would hate to throw these away.
> 
> ...


 
Home Shop Machinist featured plans a number of years ago for an end mill flute sharpener.  It had a spindle that rotated on a cushion of compressed air.  I built my own version of it and it works well, but turning the spindle and the housing to a parallel fit within a couple of thousands was no easy feat, at least for me.  However, I did get it done and I'm no expert, so it's probably worth a try.  I used aluminum for the housing and the spindle reasoning that since the spindle floats on air, there should be no wear.  Here is a picture of mine:







I originally bored a 3/4" hole in one end and a 1/2" hole in the other.  I used bushings of different diameters for different sized end mills.  A set screw held the shank in place.  I've since added an ER20 collet chuck to the 1/2" hole end.  I might add that the chuck and/or center holes need to be dead on for accurate flute sharpening.

I can provide you with more pictures and dimensions if you are interested.

Chuck


----------



## RonGinger (Nov 27, 2012)

There is a simple fixture to be used on a surface grinder that holds the mill in a 5c collet and holds the mill at the proper angle to grind the end. I have one, and it works OK, not great. Usually when a mill is dull on the end the side flutes are also dull, so doing only the end doesn't really make the mill work well.

You may find there is a shop in your area that regrinds mills. Since they are setup for this it only costs a couple $ per mill This is likely going to to get you better mills, for less money and trouble.

There was an article in a very old- maybe 1990's- HOME SHOP MACHINIST maybe by Rudy Kouhupt  for a home made gadget to go on a regular bench grinder. I built one, it never worked very well, probably because then I didnt understand proper dressing of wheels.


----------



## Stephen12 (Nov 27, 2012)

Hi Chuck,
I woud greatly appreaciate it if you could send me more details.


----------



## techonehundred (Nov 27, 2012)

The Plans for the Fixture Cfellows mentioned is also in *The Shop Wisdom of Phillip Duclos*.  This book has some fun engine projects also.  You can get it here.


----------



## chipenter (Nov 27, 2012)

Have a look at ARCurotrade http://www.arceurotrade.co.uk/Catalogue/Collets/ER-Collet-Fixtures  and an ajustable fence on the grinder table , they are out of stock of the square Stevensons fixture which is the one I am going to try out .


----------



## workshopman (Nov 27, 2012)

It will come as no surprise to you Stephen that sharpening an end mill is done in two stages, sharpening the end edges and sharpening the side edges, though not necessarily in any particular order.  However, in most machining tasks the two edges perform different tasks. The end cutting edges predominantly determine the surface finish whilst the sides remove most of the metal. 

Contrary to Ron's findings, I frequently only sharpen the ends achieving a very noticeable improvement to the finish achived. If the side edges though are less than sharp this only places more load onto the machine which can be compensated for by taking a shallower cut. Here we are talking say 6mm rather than 8mm, it not being a consideration for light surfacing cuts. 

If the side edges are to be used to surface the edges of a workpiece then in most setups the end nearest the shank can be used for the purpose as this will unlikely to have been used to cut metal. It may of course have lost a little of its edge due to careless storage.

As the end edges are only called upon to cut over a very short distance at the outer diameter, being equal to the feed per tooth, say 0.05mm, sharpening them is far from critical. The two important factors being that the end faces must all be at the same  level and must produce a very slightly concave result. The latter so that the cutter only cuts on its tip even if the machine spindle is minutely off perpendicular to the table's  traverse. 

Because of the above, sharpening the end faces can be done with very simple equipment as in its simplest form the cutter only needs to be plunged into the wheels surface. Rather than attempt to describe a method can I suggest viewing my website 

Sharpening the sides is though, by comparison, much more involved, again can I suggest another page on my website which uses a device, much like that shown by Chuck and a grinding table to control its position. See here

The grinding rest has been extensively discussed elsewhere on this forum here 

I would suggest Stephen that you first choose, say 10 end mills, and using a simple set up sharpen their end faces and determine how they work when put to use. From there, you can decide if you wish to go further with obtaining/making the move involved equipment for the side faces.

Harold Hall


----------



## bret4 (Nov 27, 2012)

The air spindle is a great way to grind end mills. Many years ago I used to grind end mills on a air spindle unit mounting on a surface grinder. The shop I worked at bought it some place. That thing was smooth as can be. Building one using a large ER collet extension like an ER20 is a great idea.


----------



## tombstone (Nov 28, 2012)

Hi Stephen       

Picture is a bench top grinder I use for sharpening cuttersit has an air spindle similar to Chuck&#8217;s which can be seen next to grindingwheel it takes 5C collets to hold cutter and runs on 80-100 psi for the airbearing as Bret stated a great way to grind end mills

it will grind them to same condition as new will also grinda range of other cutters such as reamers, c&#8217;sinks etc. This web site hastutorial videos to show how it works it used to have illustrated manuals andparts list to download but appears to have stopped doing now 

http://www.cuttermasters.com/portfolio/cuttermaster/

A large number of years ago I was taught that slot drillsare ground on end face only and end mills on either end face or flutes butthings may be changed now.

Ray


----------



## Stephen12 (Nov 28, 2012)

Thanks guys for the info, as always everybody is very helpful.


----------

