Difference btwn mill and mill-drill?
 

Hello,

I'm developing an interest in doing some of my own (light) machining
work... last time I messed w/ non-handheld metalworking tools (other
than a drill press or bench grinder) was on the
lathe and forge back in high school, so my level of experience is pretty
close to nil.

What is the difference btwn a 'mill' and a 'mill-drill'? I presume a
'mill' is a vertical mill such as I can find in Enco or Grizzly or other
importer's catalogs... and I have a fair-to-middlin' idea of what a
drill press is... so what distinguisheds a 'mill-drill' and what are
the pros and cons of one?

Thanks,

nuk

--
I know more than enough *nix to do some very destructive things,
and not nearly enough to do very many useful things.

Difference btwn mill and mill-drill?
 

"Jerry Foster" wrote:

I used to have a mill-drill and I got a lot of work out of it. Then I got a
Bridgeport and the difference was amazing. It was like swapping a battered
Yugo for a Cadillac...

Jerry


I don't have the room for a full-size mill, and used machine tools are
not very plentiful in the Atlanta area, I was thinking of the Jet
JVM-836 knee mill. Does anyone have long-term experience with this
machine?

(I wonder if any home-useful machinery will come on the market when
the GM and Ford plants close?)
--
Email reply: please remove one letter from each side of "@"
Spammers are Scammers. Exterminate them.

Difference btwn mill and mill-drill?
 

"nuk" wrote in message
...
Hello,

What is the difference btwn a 'mill' and a 'mill-drill'? I presume a
'mill' is a vertical mill such as I can find in Enco or Grizzly or other
importer's catalogs... and I have a fair-to-middlin' idea of what a
drill press is... so what distinguisheds a 'mill-drill' and what are
the pros and cons of one?

A mill is what a mill-drill tries to be. Typically, a milling machine is
much heavier, much stiffer, and generally more precise. There may be
additional features on mills that are typically not available on
mill-drills. Most mill-drills have only a quill feed for the vertical
direction -- like a drill press. By contrast, a vertical milling machine
typically has a knee that can lift the entire table up in addition to the
quill feed. Other possible differences include the ability to zero-set the
various dials, to adjust the gibs, to lock the motion in any of the three
axes, power feed, speed ranges, etc. A mill-drill will not be able to do
the heavy-duty precision cutting that a true milling machine can. For a
hobbyist, some of these differences may not matter.
There is, however, a key difference between the two machines.
Mills use collets, such as R8, 3C, B&S, and other collets and special end
mill holders, arbors, etc. The typical mill-dril, like drill presses, has
a Morse (#2 or #3) taper spindle. That spindle is not designed to take
significant side load. It is designed to take load in the direction of the
spindle axis. Collets and tooling (e.g., tool holders, arbors, etc.) are
also available for Morse taper tools. Now for the most important
difference. What holds the collets in? In milling machines, the collet is
held in place by a drawbar that screws into the back of the collet and
therefore pulls the collet shut and tight. Some mill drills have a drawbar
for the collets. Some do not. A mill drill without a collet drawbar, in
my opinion is not much better than a drill press with a good XY table. The
end will will, under any significant load, screw into the work and thereby
pull the entire collet out of the spindle. This is the main reason why
milling on a drill press is so limiting. I would reject any mill-drill that
did not have a collet drawbar.

Boris

--

-------------------------------------
Boris Beizer Ph.D. Seminars and Consulting
1232 Glenbrook Road on Software Testing and
Huntingdon Valley, PA 19006 Quality Assurance

TEL: 215-572-5580
FAX: 215-886-0144
Email bsquare "at" earthlink.net

------------------------------------------

Difference btwn mill and mill-drill?
 

Boris sez: "...The typical mill-dril, like drill presses, has
a Morse (#2 or #3) taper spindle. That spindle is not designed to take
significant side load...."

Not quite right, Boris. Every mill-drill I've seen advertised features an
R-8 spindle; they are designed to withstand the side forces of milling.
Mill-drills are true milling machines, although they lack a lot of the moves
and features of knee mills.

Bob Swinney

Difference btwn mill and mill-drill?
 

"Robert Swinney" wrote in message
...
Boris sez: "...The typical mill-dril, like drill presses, has
a Morse (#2 or #3) taper spindle. That spindle is not designed to take
significant side load...."

Not quite right, Boris. Every mill-drill I've seen advertised features an
R-8 spindle; they are designed to withstand the side forces of milling.
Mill-drills are true milling machines, although they lack a lot of the
moves and features of knee mills.

Well, maybe you haven't seen some of the cheapo's advertized. I've seen
several that use MT taper and that do ***not*** have a collet drawbar.
Conversely, I've never seen a mill-drill with an R8 spindle that did not
have a collet drawbar. My point was to warn a newby about mill-drills that
have only an MT taper, without a drawbar, and depend on luck (or crazy
glue?) to hold the collet in.

Boris

--

-------------------------------------
Boris Beizer Ph.D. Seminars and Consulting
1232 Glenbrook Road on Software Testing and
Huntingdon Valley, PA 19006 Quality Assurance

TEL: 215-572-5580
FAX: 215-886-0144
Email bsquare "at" earthlink.net

------------------------------------------

Difference btwn mill and mill-drill?
 

"Rex B" wrote in message
...

Has no one mentioned the round-column mill-drill issue?
Most mill-drills under $1000 use a round main column, which will allow the
head to move side-to-side by a small amount as it raises or lowers. If you
are lined up on a hole to drill, then have to raise the head to change a
tool, you have to re-center your cutter. Most real mills have a dovetail
column which stays centered as it goes up and down.

Good point. I overlooked that one.

Boris


--

-------------------------------------
Boris Beizer Ph.D. Seminars and Consulting
1232 Glenbrook Road on Software Testing and
Huntingdon Valley, PA 19006 Quality Assurance

TEL: 215-572-5580
FAX: 215-886-0144
Email bsquare "at" earthlink.net

------------------------------------------