[bogger44]

Little help what are the basic diff between a knee mill, vertical and such looking at one and would like to know the diff before I buy. Can you do more work with one that the other? Thanks.

[aucran]

A knee mill is a vertical mill. The "knee" is the round cylinder under the table that controls the gross Z axis (moving the table up and down). The rest of the Z axis is the quill moving up and down.

This is opposed to something like a bench top mill, where the table does not move up and down. Instead the head moves, either on a dove tail way or on a round collum.

In general, I believe the knee mills have greater overall Z clearance.

The knee mills should aslo be more massive, so more sturdy, than a benchtop mill. This means you will be able to take heavier and faster cuts.

When choosing your mill you want to consider: type of part you are planning on making, available floor space, and cost. Although, a lot will go into the type of part you planning on making, like what kind of tolerances you need, the qty, if you need to be cnc or not, etc.

[Andre' B]

Here is some info on knee and bed mills.
http://www.elrodmachine.com/Knee%20M...Bed%20Mill.htm

In short a knee mill is more versatile but tend to be a little lighter duty compared to a bed mill.

[RICHARD ZASTROW]

The typical mill often referred to as knee mills (Bridgeport & clones) are vertical turret knee mills. As mentioned above, they are very versatile.

Other knee mills such as Kearney & Trecker, Cincinnati etc. are not as versatile for small work but are more sturdy and made for heavier cuts. That's why they can have as much as 50 hp.

There is a plethora of Asian small bed type mills with turret mill heads on the Z axis slide. Sturdier than a knee mill, not quite as versatile. These are available in smaller, not quite bench top sizes as well.

As usual, the workpieces intended dictate the type of machine and the wallet determines the choice.

Dick Z

[BobWarfield]

Knee mill: Table moves up and down.

Bed mill: Spindle moves up and down.

Commercial vertical CNC's are almost invariably bed mills.

Bed mills will typically have more Z travel than a knee. Also, they can move faster in Z because the spindle head typically weighs a lot less than the table.

There are bed mills available in all sizes from small little hobby benchtops on up. See Glacern's videos for a look at a bed mill that is approximately "Bridgeport sized".

The greater versatility of some knee mills stems from their ability to swivel the head in various ways. You can hang workpieces off the side of the table where they can be quite tall and swivel the head over to reach them. Of course that swiveling action will reduce the rigidity of the mill, hence heavier duty mills often give up that feature. Bridgie's knee mill CNC's or Tree CNC's are knee mills like that.

Cheers,

BW