Knee Mill vs Column Mill

Bill:

It seems the only way I can accumulate machinery is by going through each successive step. Start with the 8" Sears table saw, then move to the Delta

10" direct drive saw, then the Delta 10" Contractors saw, then the Powermatic 66.

Then try milling on a drill press (disaster). Then try milling on a lathe... Then get a mill/drill.... Then get a knee/mill (pending)

I've not yet reached the knee mill due to financial & space considerations. However, were the opportunity to arise, I'd get a knee mill without thinking twice. The mill/drill holds it's accuracy just fine. But the inability to reposition the head accurately is a nearly constant headache. You can work around this somewhat by using collets, and trying to predict what tools you will need to mount. Each time you stretch the quill, you're comprimising rigidity. There are those that claim that it is possible to fasten the rack for the head such that it will ensure accuracy. Well, if that were 100% true, then it would seem that all the work for ways & gibs would be unnecessary.

In message , Bill writes

Bill, I bought the UK version of the G3103 and have written an article describing my opinions on my web site (see link). The only additional point is the 'y' feed is not very long (6") and in my case only 5" due to the glass scale on the dro. That said I have been able to work around it. Direct link -

The biggest reason in favor of the knee is that you don't lose your X-Y alignment when you have to raise or lower the head. Dovetail column arrangements accomplish the same thing, if the column is aligned well.

Jon

Not particularly. The main advantage of a knee mill is that you don't lose your reference when you make a vertical move longer than your quill stroke. You might do that to change a tool bit for example. As long as the mill/drill head's clamp is tight, it is not much more likely to move than the light knee mill's head (also clamped).

It is true that you want to use minimum quill extension whenever possible. That gives the cutter less lever arm to move the head. So moving the knee is better than extending the quill. But mostly avoiding chatter is about mass, Everything about a machine tool is a spring, but the heavier the spring, and the shorter the lever arm you give forces applied to it, the less it will move in response to a given force input.

So if you're concerned about chatter, pay more attention to the machine's weight than to it's particular method of establishing the relationship between cutter and work.

Gary

I bought the Grizzly G1126 about a year ago because I needed the 24 in. table movement to mill aluminum tooling plates. I had to shim the column a few thousands in one direction to get things reasonably square. I have to wear ear plugs when milling in the highest speed. Also the gear box gets rather hot after a few hours of continuous use.

I find no chatter, etc. on steel, al, plastic or whatever. The high speed is not really high enough, but the low speed is just right for drilling big holes in one inch+ steel!

A big husky vice helps a lot, too.

Paul in Redmond, OR

Personally I wouldn't get any of those.. I think you'll find the round column on the G1126 to be a pain. The G3103 doesn't have nearly enough max distance between the spindle and table - once you put in a decent sized vise, your part and a drill chuck, you'll find that you need really short 1/2" drill bits...etc.

The G3616 is also poor in the spindle-to-table department and, if you have the space for a full size mill, get a 'real' full size mill rather than this one which makes quite a few compromises. If you can, go take a look at it in person - the castings are no where near the quality of the next size up.

For a small mill/drill, I'd go with a square column - G0519 (cheaper and better than the G1126!) or I'd get a full-sized knee mill like the G9901. A used Bridgeport 9x36 is pretty compact as well. If you have space problems, Enco has a small knee mill that isn't so bad - make sure you get the floor standing version, not the benchtop. I actually prefer WTTool's version of the G0519 better than Grizzly's - the model that has the swivel table is very nice and the fit/finish quality is much higher than Grizzly's.

For some pictures of my evolution from mill/drill to full sized, take a look at:

--C.S.

I have an instruction pamphlet for a 101.22922. I have a saw model

108.22920. Without going over each individual part they seem identical. I would be happy to send you a copy of the instructions.

Yes it is.. The specs are actually very close. The printed specs on the Grizzly have a couple errors. However, the Grizzly has a three phase motor whereas everyone else does not.

--C.S.