# Hollow end mills



## Maplehead (May 9, 2017)

Hi All
Do hollow end mills exist for vertical milling machines?
I need a 3/16" hollow end mill that will insert into my 2MT collects.
If they do exist, where can I purchase them?


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## Cobra (May 9, 2017)

Do you mean an annular cutter?
https://en.wikipedia.org/wiki/Annular_cutter
I have not seen them that small.  Smallest seems to be about 7/16"


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## Bob Korves (May 9, 2017)

There are non center cutting end mills that have a hollow in the center, but it is quite shallow and small diameter on one as small as 3/16".  They are seen on 4 flute cutters, not on 2 flute.  Not sure of your purpose...


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## Frank Ford (May 9, 2017)

There are single size hollow end mills, usually special and pricey, I suppose.   And without supposing, there are adjustable hollow mills, but they are definitely expensive.  (eBay may be a decent source)

Then there are regular wood plug cutters, which can work on aluminum and other metals without modification, and possibly steel if the tooth shape is altered by grinding or by hand with a diamond pocket hone.   And, lastly ( for me at the moment) there are countersinks with interchangeable pilots, one of which might suit your purpose with the pilot removed.

Do a Google image search for hollow end mills and you'll get some ideas.


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## RandyM (May 9, 2017)

I am really confused as to why one would need a tool like this.


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## Rockytime (May 9, 2017)

Me too. Can you not just drill and bore?


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## dlane (May 9, 2017)

Coolent thru . end mills ?.


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## Maplehead (May 10, 2017)

Hi All
Thanks for the replies. Work got in the way for a few days so delayed here.
The reason for the hollow end mill is to round the rectangular portion of the top hole on the piece pictured. The top section rides in the 3/16" slots I make on another piece.
I figured it would be much quicker and easier for me to mill the top section round after drilling the hole. Just a quick end mill change.


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## FanMan (May 10, 2017)

Normally one would do that in a lathe with a 4 jaw chuck.  A trepanning tool might work, if they make them that small.


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## Bob Korves (May 10, 2017)

You can do that with a boring head and bar, like boring a hole but inside out.


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## RandyM (May 11, 2017)

Or, a rotary table.

You have many options.


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## Bill Gruby (May 11, 2017)

The cutter you seek would have to cut from the inside of the cutter, None exist that I am aware of.

  "Billy G"


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## higgite (May 11, 2017)

I could be misreading the OP, but I think he's looking for something like this, with a 3/16" ID, attached to a 2MT shank. I don't have a clue where to find one if it even exists.







Tom


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## sgisler (May 11, 2017)

Find a counter bore that takes a 3/16" pilot, run it without the pilot. Have done it many times. 




Stan
Sent from my iPhone using Tapatalk


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## Randall Marx (May 12, 2017)

Yup, Stan, I've done it too. Works well.


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## Maplehead (May 12, 2017)

Higgite, correct, basically a hollowed out end mill with a 3/16" ID. As long as it fits into one of my 2MT collects then I'm good.
The reason why I want to go tjhis approach is because it is so much quicker and easier while the pieces are set up for drilling, to just change the chuck with a collect/hollow end mill and perform the outr diameter cut.
The piece picture is made with five others all on the same piece of bar. I make all the hole cuts, taps and all and then I just cut them to separate them and they're done.
Boring and all the other suggestions I really don't understand, but they sound like a lot more set up than what should be needed.
Let me rephrase the original question.
Can an end mill, say a 3/8" or 1/2" end mill be hollowed out to have a 3/16" ID without destroying the end of the end mill bit sharpness?
If so, maybe I could pay somebody to just make me one of these.
Lastly, the depth of cut I need is only .60".


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## Maplehead (May 12, 2017)

Bill Gruby said:


> The cutter you seek would have to cut from the inside of the cutter, None exist that I am aware of.
> 
> "Billy G"


Hi Billy
I don't think so. As long as the end of the end mill cuts then it should remove the surrounding brass as the bit descends into the piece, with the .60" protrusion I want asending into the 3/16" hollow interior of the end mill.


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## sgisler (May 12, 2017)

Maplehead said:


> Higgite, correct, basically a hollowed out end mill with a 3/16" ID.



This is almost exactly what a counterbore is if you leave out the pilot. 
Tell me what size collets you have and what dimensions the face around the hole is and I can send you one from my stash. 





Stan
Sent from my iPhone using Tapatalk


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