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View Full Version : end mill grinding-part3



matador
09-19-2006, 09:26 PM
Here are a few before and after shots:
A blunt end mill.Sorry about the fuzzy pic,i was holding the chuck with one hand,and the camera in the other.Too lazy to set up the tripod:D.
http://img.photobucket.com/albums/v401/bramleynz/end%20mill%20grinding%20attmnt/emb.jpg

Here's my 1st attempt,in all it's gory detail.Not perfect,but it IS sharp.
http://img.photobucket.com/albums/v401/bramleynz/end%20mill%20grinding%20attmnt/1stattempt.jpg

And here's my last one.I'm getting better at it.
http://img.photobucket.com/albums/v401/bramleynz/end%20mill%20grinding%20attmnt/emf1.jpg

The only problem with this thing is it doesn't do the "undercut".I'm not sure what it's called,but I'm referring to the surface in front of the cutting edge.
At present I'm using a Dremel cutting disc to grind in new slots.
If anyone knows a better way,please feel free to offer your wisdom,it will be gratefully received.
I know professionals will laugh at this sort of amateur stuff,but it saves me buying new end mills all the time.I pay around $12-14US for a 12mm,4 flute,so it's wortwhile to me.
Ok,guys,let's see your comments,good or bad,or hints for improvements.

JCHannum
09-19-2006, 10:25 PM
Sharp is good, and as long as that is the result, the initial requirements have been met. The fixture looks well made, nice job.

I am having a little difficulty putting it together. Could you show a long shot of the fixture assembled with an end mill in process of being ground. I don't see how you are setting up for the primary and secondary clearance angles and indexing the lip of the end mill.

Slitting the center with a Dremel is as good a method as any. The idea is just to remove the material

torker
09-19-2006, 10:29 PM
Hans...I likey! I getting a bigger lil' pile of endmills all the time.
Have most of the components to make a sharpener out of a compound chop saw but haven't had the time to put the bits together yet.
BTW...I like your simple indexing system :D
Russ

menace
09-20-2006, 07:32 AM
Very nice! I've been searching for ideas on what to do with my 2 old valve grinders, and you may have answered my question! My B+D grinder has a stem grinder on the right side wheel which I use to square the end mill and then I've been free hand sharpening them with a Dremel!!! Now I'll try your jig, mount it on the left side, which has the X + Y for the left wheel and maybe it'll work!!
The Dremel's not too bad with a cutoff disc to sharpen, but I can't see straight or hold still, a real bitch on a straight edge!

Steve

Scishopguy
09-20-2006, 11:11 AM
Matador,

The primary angle is that little bit of clearance at the edge, which does the cutting. There is also a slight angle from the center axis to the outer diameter, only about 2-3 degrees if memory serves correctly. Enco makes a fixture that has all three angles built in. The block that is the base has the 2-3 degree angle machined on the bottom so the whole fixture sits that far off vertical. This is in the y axis. The x axis has the primary cutting edge angle, of about 7 degrees, machined so that the whole thing is 2-3 degrees off in the y and 7 degrees off in the x. At the end of the x direction you have a more agressive angle of about 15 degrees. There is a collet holding fixture that is attached to the top of this block that lets you index the end mill so that the flute to be ground is level.

Sorry if I have everyone totally confused but the thing is really a simple design and works very well on the surface grinder. I am going to have to buy or make one since I no longer have access to the one I used for so many years.

Scishopguy
09-20-2006, 09:21 PM
I just had a wild idea when I read Russ's post about using an old chop saw. I have one of those cheap little HF chainsaw sharpening setups. It works fine on a chain saw but you can adjust the cutting angle on it to as much as 45* either side of zero. I'll bet it would not be hard to set up with some sort of indexing fixture (like maybe a spin grinding jig??) and touch up end mills.

Just a wild a$$ed thought.