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

Reply to
nuk
Loading thread data ...

A mill-drill is a VERY heavy (typically 750 lbs or so) drill-press type of machine with an XY table. It is designed to take a heavy side-load on the spindle and uses collets instead of a chuck. It is intended for the "hobby" market and, within its limitations, can do basic machining.

A true mill is a serious machine. The "gold standard" vertical mill is the Type 1 Bridgeport. It weighs in at about a ton and a quarter (and, yes, it can drill, too...). And there are vertical mills which are much larger. Somewhat less versitile, but superior for some kinds of work is the horizontal mill. While there were a few small ones made, most are very large, powerful machines intended for cutting large, flat surfaces.

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

Reply to
Jerry Foster

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.

Reply to
Doug Warner

"nuk" wrote in message news: snipped-for-privacy@panix2.panix.com...

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

Reply to
Boris Beizer

Boris sez: "...The typical mill-dril, like drill presses, has

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

Reply to
Robert Swinney

I daresay more Mill-Drills are sold today with R8 spindle than MT. That is definitely the way to go unless you have aton of MT tooling for another machine, like your lathe. Even then, I'd probably go for R8, because it is so miuch more available and cheaper.

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. Not a deal-killer neccessarily, but an important difference. A good middle ground is the Seig X3, which Grizzly sells under another number for less than $1000.

Reply to
Rex B

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

Reply to
Boris Beizer

Good point. I overlooked that one.

Boris

Reply to
Boris Beizer

PolyTech Forum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.