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lwalker
05-07-2008, 09:08 AM
I've been reading the Carbide thread (http://bbs.homeshopmachinist.net/showthread.php?t=28908) with interest especially because I've been thinking of getting one of the import 1" insert face mills.

Now that I've read that the insert pockets on the cheaper mills are generally make with zero rake I've been looking at shell mills in the same price range.
Bringing me to the question: in what cases would you want a shell mill over a standard end mill and would a 1.5" shell mill give a reasonably good finish when used as a facing cutter?

lazlo
05-07-2008, 09:34 AM
"Shell mill" is usually the same thing as face mill, although I've sometimes seen it used to mean the solid (non-insertable) HSS cutters that use the same arbor as an insertable facemill.


Now that I've read that the insert pockets on the cheaper mills are generally make with zero rake I've been looking at shell mills in the same price range.

Only the cheapest TPG facemills have zero rake. The Grizzly TPG facemill is Chinese, and its designed correctly. $59:

http://www.grizzly.com/products/Fly-Cutter/G2861

http://www.grizzly.com/images/pics/jpeg288/g/g2861.jpg

The PennTool "Precise" house brand TPG facemill is also Chinese, and its also got the correct pocket. Same price as the Grizzly:

http://www.penntoolco.com/catalog/products/products.cfm?categoryID=6830

http://www.penntoolco.com/images/catalog/6830.gif

in what cases would you want a shell mill over a standard end mill and would a 1.5" shell mill give a reasonably good finish when used as a facing cutter?

A properly designed facemill will leave a beautiful finish, even better than a flycutter. This is a cast iron surface plate that I faced with a 3" Sandvik RA-245, 4 toothed facemill. The top 3" has been facemilled, the bottom 3" is rough milled. That's the grain of the grey cast iron -- the surface is smooth as glass:

http://i164.photobucket.com/albums/u15/rtgeorge_album/SEHInserts019s.jpg

ERBenoit
05-07-2008, 09:57 AM
Bringing me to the question: in what cases would you want a shell mill over a standard end mill and would a 1.5" shell mill give a reasonably good finish when used as a facing cutter?

A shell mill and an insert face mill are not the same. Face mills are for facing, usually not a taking a very deep or heavy cut. Shell mills are for milling where you have large diameter to a depth of cut need, or to, by using a roughing shell, hog off material. A shell mill can offer a depth of cut that you cannot achieve with a face mill.

A shell mill is basically and end mill with an interchangeable arbor. A shell mill offers the advantages of various larger diameter end mills using a commom arbor. Shell mills in larger diameters often cost less than a one piece endmill of the same diameter.

Fasttrack
05-07-2008, 10:03 AM
A shell mill and an insert face mill are not the same. Face mills are for facing, usually not a taking a very heavy cut. Shell mills are for milling where you have a need to and can hog off material. A shell mill can offer a depth of cut that you cannot achieve with a face mill. Example: You want to mill a 2" wide, 3/4" deep step along the edge of a piece of aluminum. With a ridgid enough set up, you can do this in one pass with a shell mill, not so with a face mill.

A shell mill is basically and end mill with an interchangeable arbor. A shell mill offers the advantages of various larger diameter end mills using a commom arbor. Shell mills in larger diameters often cost less than a one piece endmill of the same diameter.


Thats what my text book says in not so many words.

ERBenoit
05-07-2008, 10:13 AM
Thats what my text book says in not so many words.
Apparently I didn't write your book. :D

Fasttrack
05-07-2008, 10:30 AM
LOL

Don't take me the wrong way, I just wanted to add my vote to what you said. My book doesn't go into depth on the differences, just mentions it in passing, so to speak.

lazlo
05-07-2008, 10:30 AM
1.5.e) SHELL MILL

Shell mills (often referred to as face mills) cut predominately on the end, or face. They resemble a very large diameter end mill with a very low length to diameter ratio.

Fig 1.5.5.

http://machine-tools.netfirms.com/images/fig_1_5-5.jpg

lazlo
05-07-2008, 10:45 AM
"Shell mill" is usually the same thing as face mill, although I've sometimes seen it used to mean the solid (non-insertable) HSS cutters that use the same arbor as an insertable facemill.


A shell mill is basically and end mill with an interchangeable arbor.

This is a Niagara T-15 "shell mill" on the left, the Sandvik RA-290 on the right. Notice that they use the same arbor :)

http://i164.photobucket.com/albums/u15/rtgeorge_album/ShellMills.jpg

ERBenoit
05-07-2008, 11:09 AM
This is a Niagara T-15 "shell mill" on the left, the Sandvik RA-290 on the right. Notice that they use the same arbor :)

http://i164.photobucket.com/albums/u15/rtgeorge_album/ShellMills.jpg

Didn't say that face and shell mills cannot share the same arbors. The difference in face vs. shell is in DOC capabilities.

ERBenoit
05-07-2008, 11:11 AM
LOL

Don't take me the wrong way, I just wanted to add my vote to what you said. My book doesn't go into depth on the differences, just mentions it in passing, so to speak.


Wasn't taking your comment the wrong way, just trying to be funny. :)

lazlo
05-07-2008, 11:18 AM
Didn't say that face and shell mills cannot share the same arbors.

I was referring to the fact that you're one of the folks who makes the distinction that I described in the first line of my post :)


Originally Posted by lazlo
"Shell mill" is usually the same thing as face mill, although I've sometimes seen it used to mean the solid (non-insertable) HSS cutters that use the same arbor as an insertable facemill.

ERBenoit
05-07-2008, 09:39 PM
I was referring to the fact that you're one of the folks who makes the distinction that I described in the first line of my post :)


Originally Posted by lazlo
"Shell mill" is usually the same thing as face mill, although I've sometimes seen it used to mean the solid (non-insertable) HSS cutters that use the same arbor as an insertable facemill.

Sorry, I must have missed that little bit.