# End Mill Sharpening Attempt



## ericc (Jan 29, 2016)

Recently, I was in the TechShop, which is a shared machine membership facility.  Usually, there are some end mills in the mill box.  They are often not in very good shape, but they do work a little bit.  This time, there were only two.  One had the end snapped off.  It would still work for side milling.  The other just had a burned up end.  I thought it might be fun to try to see if I could sharpen the end mill by hand on the grinder.  There was no dresser available, so the right edge of the wheel was a little rounded.  The primary relief was ground at about 5 degrees with a slight angle in towards the center to form a dish.  The resulting grind did cut, but it left a furrow down the center-line of the slot.  Is this caused by not gashing the end mill correctly.  These are kind of junk community end mills, so there is nothing much lost if they are goofed up a bit.  By the way, it was much improved by the grinding session.


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## Kernbigo (Jan 29, 2016)

I ground some in my mill with a wheel with the 1/4" shaft mounted in the wheel. I used a v block and just turned it 180 deg., a 2 flute set the primary angle about 5-8 deg. and the secondary about 15-20 deg., it cut good. Set the mill spindle speed as high as it will go.


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## pineyfolks (Jan 29, 2016)

We have no techshop type facilities here but I think if we did I would pick up some of my own tooling and take it with me. The small amount you'll spend will make things easier and your projects will turn out much better. And don't forget to take them home with you.


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## One-match fire (Jan 29, 2016)

As a result of the passing of time, one of my friends here in this small town, had to dissolve his collection of equipment and after failing to sell any of it, decided to "give it away".  What happened was that he advertised, "If you come get it, you can have all of it".  Included in this amazing collection of sharpening machinery was a Darex E-90, built exclusively for the purpose of sharpening end mills.

The machine is NOT all that complex in terms of its operation but is quite elegant in its design.  While I am still a rank novice at its operation, there should come a time in the "NOT TOO distant future" when I would be willing to take on such a task in trade for a task I need...(yes, I like the barter system).

Once my skill has achieved a relative "journeyman" level I'd post again and you'll be welcome to send your endmill for proper care and sharpening...assuming you have not already done so...
Cheers,
Trim sends


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## tpic402 (Jan 29, 2016)

One match fire, I also have a Darex e-90, got it for a little trade it is brand new it does take a little getting used to, I have the opportunity to buy a e-90 along with a darex drill bit sharpener(the kind that looks like a bench grinder)  2 Foley saw sharpener one for hand saws and one for circular. The gentleman told me I could have them for $500.   What do you think.


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## One-match fire (Jan 29, 2016)

The Darex E-90 sells new for about $2900 (on sale right now).  The same company makes the "Drill Doctor" and I have two of them. I love them. Easy to use and quick as well as they work well.

The Foley saw sharpeners would be difficult to say anything about because I don't know the model numbers.
I have a 360, a 380 (router and drill/mill bit sharpener) SF 1000, SR1000, and SS 1000.  I also have a 357 and 367.  The 367 is the newest of the carbide grinders.  I also have a few odds and ends, like a FB 225 scissor sharpener (which I love).

I have a 387 filer as well as the SF1000. I have 5 of the tooth spacing rods (can't remember the nomenclature,) two of the straight carrier assemblies, one crown carrier and one miter saw carrier.

I have used the SF1000 a few times, primarily to learn how to use it.  Following the instructions is key.

The 387 has no motor but is so much like the SF 1000 that following the instructions makes it very simple to use by cranking it by hand...(in case the "lights go out").  

The 367 got damaged on moving it to my shop but I've repaired it and have it set up and ready to start trial sharpening.  I have some older carbide blades to "learn on". I have the 357 all ready to go but I need the "Hook and Top Clearance Chart" which seems to be critical to getting things done right.
Cheers,
Trim sends


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## Charles Spencer (Jan 30, 2016)

pineyfolks said:


> We have no techshop type facilities here but I think if we did I would pick up some of my own tooling and take it with me. The small amount you'll spend will make things easier and your projects will turn out much better. And don't forget to take them home with you.



I'd go one step further even.  A small portable tool box with drill bits, end mills, lathe bits, a scriber, combination square, center punch, micrometer, and ball peen hammer.  This should make your work both quicker and more accurate.  You'd probably be able to think of a few other small items related specifically to what yopu're trying to do.


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## Bill C. (Jan 30, 2016)

Nice looking grinder, http://www.darex.com/drill-sharpeners-and-grinder/e90-17/e90-end-mill-grinder-and-sharpener.html.


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## Paul in OKC (Jan 30, 2016)

Sounds like you nay not have removed enough of the 'middle' of the mill. I would not worry about keeping the center cut aspect of the cutter, if it is one, and 'gash' the center. It will work for every thing except making a fresh hole.


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## derf (Jan 30, 2016)

I understand the "gashing", but what type of wheel to do it with......especially for carbide?


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## ericc (Feb 2, 2016)

Hi.  Thanks for the offer and information.  These are community consumables, and have to be left in the shop.  When I need to get something done, I have my own end mills that I got at a garage sale.  They are name brands, in excellent condition, and seem to perform well.  Most of the other people using the mills bring their own bits, and have favorites.  Most of them use generic carbide end mills that they get online, such as at Enco, since these seem to provide the most bang for the buck.  I am afraid that I am still too much in the beginner stage for that right now.

The past weekend, I looked at the milling machine community box and noticed that someone had gashed the end mills that I attempted to sharpen.  I think that I have the geometry down now, and further experimentation might prove fruitful.  From what I saw, gashing is pretty straightforward if the end mill can afford to lose any center cutting ability.  Just make an x in the end with the corner of the wheel.  The wheel must be dressed sharp.  As mentioned above, it is challenging for carbide, since the green wheel at TechShop is never dressed sharp.


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## derf (Feb 2, 2016)

I just got my cutter grinder up and running recently and have sharpened mostly carbide end mills. I have the primary and secondary angles figured out, but when it comes to gashing them, it looks like I need a thin wheel. Looking at new endmills, it appears that the gashing was done with a wheel no more than about .090" thick, and it has a slight bevel on both edges. Does someone make a wheel just for doing this?


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## One-match fire (Feb 2, 2016)

I wondered about that myself.  Every time I try to sharpen an endmill, I never seem to be able to get that cross cut that I think you are calling a "gash".  It seems to make the endmill look nice but is it "important"?  My Darex-E90 doesn't mention anything about that in the instructions or in the videos...
Any one know if it is important or not?  If it is, what is the reason?
Trim sends


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## One-match fire (Feb 2, 2016)

Bill C. said:


> Nice looking grinder, http://www.darex.com/drill-sharpeners-and-grinder/e90-17/e90-end-mill-grinder-and-sharpener.html.


That is the one I have.  Works pretty well. You have to have compressed air to make it work though.  The rod that holds the collet is "air lubricated" and glides real nice with that compressed air moving through it.  Works well for the plasma cutter, too!


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## One-match fire (Feb 2, 2016)

tpic402 said:


> One match fire, I also have a Darex e-90, got it for a little trade it is brand new it does take a little getting used to, I have the opportunity to buy a e-90 along with a darex drill bit sharpener(the kind that looks like a bench grinder)  2 Foley saw sharpener one for hand saws and one for circular. The gentleman told me I could have them for $500.   What do you think.


If all of them are in really good condition, I'd think $500 is pretty good.  But I am NOT an expert on anything.  I'm still trying to learn how to "silver solder" a carbide tip to a steel blade without melting the blade... I am a slow learner...
Trim sends


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## 4GSR (Feb 5, 2016)

derf said:


> I just got my cutter grinder up and running recently and have sharpened mostly carbide end mills. I have the primary and secondary angles figured out, but when it comes to gashing them, it looks like I need a thin wheel. Looking at new endmills, it appears that the gashing was done with a wheel no more than about .090" thick, and it has a slight bevel on both edges. Does someone make a wheel just for doing this?



They do make and sell "thin" diamond wheels for gashing the ends on end mills.  I bought one of the Chinese import ones off of Ebay.  The only problem is, you may have to make a arbor or bushing, or bore it out to hold it in your cutter grinder.  I haven't had a chance to set up and try the one I bought.  Also have a couple of diamond cutoff blades that should work on much smaller ones like 1/2" and smaller.


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## One-match fire (Feb 5, 2016)

Will one of you please explain "gash" (one photo will probably do it all,) 
Is a "gash" actually necessary and if so, why?
Can the end mill perform without a "gash?"
I'm so new I just don't know. 
Thanks


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## derf (Feb 6, 2016)

The picture is not the best, but you'll get the idea. The gash puts more relief in the 2 opposing flutes for center cutting ability. Without the gash, the mill won't plunge very well.


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## One-match fire (Feb 6, 2016)

OK, Now I get that. I have been sharpening the endmills without the gash and they just never looked "right" because I wasn't adding the gash.  Now, the question becomes how is that gash made once you have sharpened the endmill to the primary and secondary relief? Is it cut first or after the primary and secondary relief is ground?

Is PLUNGE a critical and ALWAYS required feature?  Will the endmill cut surfaces without having to PLUNGE or is that the entire purpose of doing the surface?
Someone mentioned a thin diamond wheel to do it. Is there any other technique to do it?  If so what and how should it be performed?

As you can see, I am a rank amateur but can learn.  I would like to be able to help the machinists in my area as well as do my own work.  This learning is helpful for those activities.
Thanks
Trim sends


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## derf (Feb 6, 2016)

The ability to plunge is critical if you are milling pockets. If you are starting on an outside edge it makes no difference if you only step over 1/2 the dia. of the cutter. I'm guessing the gash is done after the 1st and 2nd relief, just for the fact that now you know how deep to go. A HSS endmill could be done with a cut off wheel, even freehand if you were steady, but carbide will require a diamond wheel, I just haven't found one yet.


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