Subject: Re: Basic milling question

From: [email-masked]
Date: Sat, 07 Dec 96 18:16:58 PDT

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> Subject: Basic milling question
> Date: 7 Dec 1996 16:21:21 GMT
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>      When to use a two flute end mill, and when to use a four flute end
> mill ?
> 
>      Thanks in advance,
> 
>      A. Levy
> 
DoAll has or had a book that is very good in explaining this
and otherr facts about end mills, it is 
 END MILLING HANDBOOK it was $6.00 ten years ago.
The short answer is that 2 flute are for slots. The books shows why 
with drawns.

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From: [email-masked] (Jens)
Date: Fri, 06 Dec 1996 20:23:40 -0800

>     When to use a two flute end mill, and when to use a four flute end

Two flute is used when cutting a slot or when plunge cutting
4 flute gives a better finish or faster cut due to the extra edges but
has problems in a slot/plunge situations (works but you got to watch
it) 

When cutting soft material you might be better off with 2 flutes as a
4 flute might clog up (smaller chip clearance spaces) 

Jens

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From: [email-masked]
Date: 7 Dec 1996 16:21:21 GMT

Thanks in advance,

     A. Levy

---

From: [email-masked]
Date: 8 Dec 1996 17:10:14 GMT

>     When to use a two flute end mill, and when to use a four flute end

Two flute cutters are for roughing out. They have more chip clearance, can
be run at a faster speed but leave a lumpy finish.

Four flute are for a better finish, usually a slower spindle speed and
feed. More cutting edges per rev means a better finish.

Unless you are really into production times for machining, I would only
use four flute as they are a better universal approach than two flute.

Two flute in smaller sizes (3/8 and less) are weaker as they cut a lot of
material out to make the cutter. It becomes a moot point when roughing
with them as you have to slow up the feed anyway.

FWIW, I have almost exclusively four flute cutters. I mill at least 4
hours of every day.

Peter

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From: David Fogg <"[email-masked]"@worldnet.att.net>
Date: Sun, 08 Dec 1996 01:57:15 -0500

Jens wrote:
> JensJen is correct. Just a note: 2 flute endmills are center cutting, most 4 
flute endmills are not unless they are made especially for center 
cutting

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From: Steve Wellcome <[email-masked]>
Date: 9 Dec 1996 13:41:45 GMT

Two flute end mills are better for slotting, as they cut more nearly
to size when "buried" in a slot than do 4-flute end mills.  George
Thomas explained the geometry of why this is so years ago in a back
issue of Model Engineer.  It may also be in his Model Engineer's
Workshop Handbook.

You don't *have* to use a 2-flute end mill for slotting though.  If
you make an initial pass with a slightly undersize end mill, then 
follow it with a to-size 4-flute end mill, you'll do okay too.

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From: [email-masked] (ALevy01)
Date: 13 Dec 1996 08:31:05 GMT

Thanks to all who responded to my question. Your answers were most
helpful.

     - A. Levy