Full Circle

 This was a very aggressive cut for my Mini Mill.  I was hanging over the limits, and had a couple incidents where this became obvious.  The Chuck is held to the Quill with a Morse Taper.  This is the way that Drill Presses typically hold the Chuck.  It is perfectly OK when you are drilling, down cutting into the material, because the force applied to the Quill, Morse Taper, Chuck, and Bit is downward.  This keeps the Morse Taper thoroughly seated, and locked.  You will never have a problem drilling.

I call this thing a Mini Mill.  OK, there in lies the problem.  I'm milling, side cutting, with no downward force.  The force applied to the cut is from the side, and is a cutting action so this force is cyclic causing vibration.  This applies the force through the Bit, into the Chuck, on up to the Morse Taper, and into the Quill causing the entire machine to vibrate with this sideways force.  Drill presses are not meant to do this.  Some would say this type of cutting is not possible, and you will never get a good cut.  I'm going to say that is wrong.  You can use you drill press as a Mill when you keep everything tight, don't over load the machine, and make relatively small cuts that don't create excessive vibrations.  The depth of the cut is relative to the amount of vibration you get, and the tool will let you know when you are cutting too deep.

In the first incident the Chuck came off the Morse Taper while I was cutting.  The Chuck stopped spinning, and I had to abort the cut.  There was no adverse effect because when the Chuck is disconnected from the Morse Taper it will stop spinning.  In the second incident the Morse Taper came out of the Quill.  In this case the Mill continued to spin, and I kept cutting, but the cut was going deeper as I went around the radius of the part.  The amount of vibration, and noise that the machine was making increased.  I noticed it visually, and then immediately aborted the cut.  This did have an effect, but that effect was the cut got deeper, and didn't affect the radius of the cut.  If anything it caused the Mill to move away from the radius of the cut.

This is the Mini Mill configured to cut the radius of this part.  There are a lot of things that I can improve on this machine.  I noticed that the X Axis will move with vibration, and I had to work around that issue.  It would be nice to have clamps that hold the axes that don't move with a cut.  There is not depth hold on the Z Axis, really another clamp, but with this cut I was holding the Z Axis with one hand, while doing the part feed with the other hand.  It does have a depth limit, but not a hold at depth clamp, and that would be handy, LOL!  Milling machines have a screw that goes through the Quill, Morse Taper, and Chuck which holds the rotating assembly together vertically, and that, also, would have been very handy.  Then there are the bearings that the Quill is riding on.  In a Drill Press these bearings are meant to handle a downward force.  With a Milling Machine these bearings are capable of handling downward, and side loaded forces.  I think what I am telling myself here is this I need a Milling Machine...  and a Lathe...