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Chipped corner on 2 flute end mill. Any fixes?

Cfar

Plastic
Joined
Sep 11, 2021
Hi experts. I was taking a 'heavy' pass through some mild steel earlier today and forgot that my vice is a bit undersized for my machine.... Seems newbie karma got me, the stock pulled out of my vice and decided to fling around a bit. In doing so smacking into my favorite, and only 1" Niagara HSS end mill that I was using for this pass.. It unfortunately put a decent sized chip in the one cutting corner of the two flutes. Please note, my heavy pass, is probably your finishing pass. I rarely use my mill to full potential and am quite scared of doing actual passes as I fear stuff like this happening, and I cherish my 'cheap' hss tooling because I have so little of it. Please see attached images. Is there any way I can repurpose the end mill? Or perhaps fix the chip? It is still useful for cutting but leaves a hideous finish. Maybe I'm just plain dumb, but I'll let the experts decide... P.S. I'm happy I decided not to go for carbide tooling as it probably would've come off a lot worse due to the brittle nature. I'm gonna swap back over to a more sizeable vice after this to prevent it from happening again. I mainly use this end mill for surface finishing so

Any useful advice or similar experiences would be appreciated.

Chipped corner.jpg
I mainly use this for surface cuts, rarely using the sides so I really need a good cutting edge which the chip obviously has effected.
 

michiganbuck

Diamond
Joined
Jun 28, 2012
Location
Mt Clemens, Michigan 48035
Having a bench grinder you can regrind an end mill by hand. You rough snubb grind the end on the OD of the wheel to take away the wear land using a square to make it fairly square-ended.

Rough grind the clearance angles to just sharp.

Fixture the end mill to be horizontal to the side of your grinder and lightly touch the wheel side to make a witness grind that is very square.

Then you grind the clearance carefully like grinding a lathe tool bit to just grind away the witness mark to sharp.

*Another (better) choice is to wrap it in paper to protect the OD from damage, and then accumulate perhaps 6 dull end mills. Then you take them to a local grind shop and pay about half the price of new for a resharpening.

*It can be good to check parts with a file before trying to mill, If a file won't file the material then it is too hard to mill with a HSS cutter.

Often a mill vise will spring a little and so not hold part very well. A shim 1/8 by .020 set high on the part and on the moving vise jaw can make parts hold better in a mill vise.

What happens is that a vise can spring and so the vise jaws are not parallel and only holding at the bottom of tha part/the shim avoides doing that.
 

Booze Daily

Titanium
Joined
Sep 18, 2015
Location
Ohio
You could use the other corner as a boring bar in the lathe.
You could just grind some relief on the chipped corner so it cuts again and you'll have a rougher/finisher all-in-one tool.
 

Bobw

Diamond
Joined
Feb 8, 2005
Location
Hatch, NM Chile capital of the WORLD
Having a bench grinder you can regrind an end mill by hand.

I find doing hand work like that on HSS a lot easier on a small belt sander..
The cheap little ones, a 1x30, they are only like $50, used to be only $20.

On the bench grinder thing. The cheap ones are too darn fast. Even a 3200rpm
can be a little quick, and those aren't that cheap. Though I prefer a 1700, that's
where the green wheel lives.
 

Zeuserdoo

Aluminum
Joined
Aug 31, 2015
Location
The Moridor
I would grind a radius on the bad corner, enough to remove the damaged area, and then grind the same on the good corner and poof! You now have an endmill with a corner radius.
 

GregSY

Diamond
Joined
Jan 1, 2005
Location
Houston
I'm curious how you were able to hold a 1" end mill and what machine your were holding it in.....maybe an R8 7/8" collet as the end mill looks to have a smaller shank.

Either way....that's life. A 1" end mill is not pleasant to buy, but damaging one is also not the end of the world. Throw it in the drawer and use it when you can make use of its side edges.

You don't say where you are in Texas but if you were local I'd give you a 1" end mill....but all of mine have 1" shanks so maybe it wouldn't work for your setup.
 

Joe Henderson

Aluminum
Joined
May 21, 2006
Location
Blooming Grove, Texas
Depending on where you're at I can put you in touch with a guy that sells tooling at decent prices. You can hand grind it or just use the sides to mill. Define heavy cut? light machines don't have the ass to do much heavy metal removal. Roughing end mills are your friend there and moderate cuts.
 

dcsipo

Titanium
Joined
Oct 13, 2014
Location
Baldwin, MD/USA
Hi experts. I was taking a 'heavy' pass through some mild steel earlier today and forgot that my vice is a bit undersized for my machine.... Seems newbie karma got me, the stock pulled out of my vice and decided to fling around a bit. In doing so smacking into my favorite, and only 1" Niagara HSS end mill that I was using for this pass.. It unfortunately put a decent sized chip in the one cutting corner of the two flutes. Please note, my heavy pass, is probably your finishing pass. I rarely use my mill to full potential and am quite scared of doing actual passes as I fear stuff like this happening, and I cherish my 'cheap' hss tooling because I have so little of it. Please see attached images. Is there any way I can repurpose the end mill? Or perhaps fix the chip? It is still useful for cutting but leaves a hideous finish. Maybe I'm just plain dumb, but I'll let the experts decide... P.S. I'm happy I decided not to go for carbide tooling as it probably would've come off a lot worse due to the brittle nature. I'm gonna swap back over to a more sizeable vice after this to prevent it from happening again. I mainly use this end mill for surface finishing so

Any useful advice or similar experiences would be appreciated.

View attachment 349175
I mainly use this for surface cuts, rarely using the sides so I really need a good cutting edge which the chip obviously has effected.

34832 - End Mill Grinding Fixture and

one of these chucked in your mill

Norton 66243529183 $38.69 Flaring Cup Toolroom Wheel, 3 in. dia. | Zoro.com
 

Mtndew

Diamond
Joined
Jun 7, 2012
Location
Michigan
Next time use an end mill that has at least 4 flutes. 2 flutes is asking for trouble if you're not experienced.
 

michiganbuck

Diamond
Joined
Jun 28, 2012
Location
Mt Clemens, Michigan 48035
Here is the video in the end mill fixture mentioned in post #11.

The guy in this video is pretty sharp and made a good go of using the fixture. It uses straight wheels not cups. I would recommend that one would V block grind the end and then sharpen grind to just take away V blocks flat grind, this is because the fixture seems to not have a precision index.

Shoot'n The Poop #1 - End Mill Grinding Fixture - YouTube

The video looks dangerous because one would think he is climb-grinding, but his grinder spins the other way so he is doing it correctly....so the wheel does not catch and pull the part under.

A good chance a green grinder hand might have difficulty with this device...the first use.
 

Gordon Heaton

Stainless
Joined
Feb 19, 2007
Location
St. George, Utah
. . .Often a mill vise will spring a little and so not hold part very well. A shim 1/8 by .020 set high on the part and on the moving vise jaw can make parts hold better in a mill vise. What happens is that a vise can spring and so the vise jaws are not parallel and only holding at the bottom of the part/the shim avoides doing that.

Even more likely, the sides of the part weren't parallel, as when using hot rolled material as-is. In these cases just use a leather or heavy paper strip between the moving jaw and the part for a more secure grip. Avoid most plastics, they're too slippery.
 

Nmbmxer

Hot Rolled
Joined
Jun 22, 2008
Location
VA
You can spin grind a circular chamfer on the corners then very carefully use a bench grinder to add clearance. Blue it and carefully sneak up on it and finish with a stone. Any error will change the chipload from one side to the other so be careful.
 

Laverda

Cast Iron
Joined
Mar 24, 2014
Location
Riverside County, CA
Go to Ebay. You will probably find a new end mill for cheaper than trying to fix this one. It may take a week or two to find the exact one you need.

Any time I need a mill that is an expensive size and may only be used once, Ebay is where I look.

I bought a new Kyocera 3/4" solid carbide end mill six months ago for $17. It took weeks looking to find one this cheap but was worth the wait.
 

guythatbrews

Cast Iron
Joined
Dec 14, 2017
Location
MO, USA
What kind of vise is it? Some are atrocious and don't hold well no matter what you do. You may need a new vise.

I agree to hand grind back to square. It works in a pinch and is a good skill to have if you don't have the proper equipment. Also agree 2 flute is not the best for face milling. Might as well use a fly cutter. They are easy to hand sharpen.
 

Cfar

Plastic
Joined
Sep 11, 2021
I'm curious how you were able to hold a 1" end mill and what machine your were holding it in.....maybe an R8 7/8" collet as the end mill looks to have a smaller shank.

Either way....that's life. A 1" end mill is not pleasant to buy, but damaging one is also not the end of the world. Throw it in the drawer and use it when you can make use of its side edges.

You don't say where you are in Texas but if you were local I'd give you a 1" end mill....but all of mine have 1" shanks so maybe it wouldn't work for your setup.

GregSY, thanks for your response. I am on a cincinatti toolmaster 1C. NMTB40 taper. I use ETM spring collet holders which go up to 1" in holding diameter capacity. I don't do enough work with end mills to invest in proper holders with set screws. I believe this particular end mill has a shank diameter of 3/4". Thanks for your offer on the tooling. I live near Huntsville up north of Houston. I think I will probably just attempt to equal the cutting edges out so it will give me a half decent finish. The real problem my newbie self seems to be having is that I am using quite a powerful and rigid mill, which is geared, and it just loves ripping anything out of my hobby vice. I have a much larger machinist vice.. but I rarely do large work so it is a pain to always be swapping back, especially with how heavy it is. I would've started out life on a minimill or something small, but my dad bought the toolmaster at an auction a few years back and it had been gathering dust ever since and I honestly felt bad for it.
 








 
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