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View Full Version : Relieving carbide end mill shanks



Erik Brewster
07-30-2012, 04:07 PM
I needed some long reach 0.015" end mills for a project that had a reach of about 0.2". That is a crazy end mill with 13x diameter reach, but I could get away with a 0.06" relieved shank up to 0.2", which, while certainly an odd ball end mill, at least is mechanically more reasonable. I found some reasonably priced end mills on ebay and went about relieving the shank.

I used a shars diamond grinding wheel mounted in my lathe because I didn't have an appropriate grinder to use. I played around with it until I could get runout < 0.001". I then mounted the end mill in my dremel flex attachment. I set the dremel to the slowest speed and the lathe to 1000 rpm-ish. The dremel is really horrible as far as bearing precision and backlash (I can move it visibly with my fingers), but I figured it might do, seeing as I was just relieving the shank, not modifying any cutting edges. It turned out great.

I fed the bit into the wheel 0.0005" at a time and waited for the grinding action to stop making any noise (~ 5 sec), then would feed it in again, until I reached target size. I was able to hold size to 0.001" on diameter with no special attention paid, other than working to the numbers on the DRO.

I was really surprised how well this worked, considering how poorly the dremel structure flexes and bearings are all over the place, so I thought I would share.

http://i46.tinypic.com/n2iqdf/6

http://i46.tinypic.com/29nceme.jpg

DICKEYBIRD
07-30-2012, 05:47 PM
Wow, that's a real "Git'r done" solution Erik! I'll file that one away for future use 'cuz that's my kinda rig right there.:D

I figured somebody'd eventually figure out how to make those Chinese diamond wheels run true!;)

becksmachine
07-30-2012, 05:55 PM
Cool set up, but I want to see the project! :eek:

Dave

Erik Brewster
07-30-2012, 07:37 PM
Cool set up, but I want to see the project! :eek:

Dave

It's for an engagement ring. Here are some pictures:
http://bbs.homeshopmachinist.net/threads/55360-Making-engagement-ring?p=787534#post787534

oldtiffie
07-31-2012, 04:45 AM
Wow, that's a real "Git'r done" solution Erik! I'll file that one away for future use 'cuz that's my kinda rig right there.:D

I figured somebody'd eventually figure out how to make those Chinese diamond wheels run true!;)

Well DB, I guessiots where and how you shop and how much you are prepared to pay.

Here are a copule of my diamond wheels that came with my T&C grinders and they are/were vey accurate:

http://i200.photobucket.com/albums/aa294/oldtiffie/Grinder_work-head_demo/Grind_work-head_demo1.jpg

http://i200.photobucket.com/albums/aa294/oldtiffie/Grinder_work-head_demo/Grind_work-head_demo5.jpg

But when I get them I do a check alignment and take a skim cut if necessary.