Face mill larger than work?

[photomankc]

Ok,

Stupid question. I have Glacern 2.5" FM45 to try out with my X2. Up till now I have been using larger end mills to face and they are usually smaller or just a bit larger then the workpiece. Now in many cases the face mill will be a good bit larger than the work. My question is: Is there a right/wrong way to approach the cut when the mill is much larger. Should I run right down the center? Should I let the mill skim into the cut by running down one side?

I was thinking that coming down the middle would seem to have the cutting face slamming into the material harder than running down the side and raking into the cut.

[LeeWay]

I don't know how the old pro's do it, but I run it down the middle.
I start with the mill off to the side so that the lead in doesn't actually hit the part.
I finish will the mill past the part before lifting.
This gives me one fluid motion on the part and comes out looking nice.

[Geof]

On a small machine without substantial rigidity you could be better off coming along the side to have a more gentle entry into the cut. However, many face mills have an angled entry anyway and the rpm is normally low, especially without lots of horsepower, so running straight down the middle could be fine and get things done quicker.

Having written that though, I often run down the edge in climb milling mode with both end mills and facemills because this reduces the formation of burrs. Try it both ways and you will see what I mean; if you have the tool leaving the edge of the work under full cut it drags a burr out even when it is new and sharp. When it is dull it can create a terrible ragged burr that is a nuisance to clean off if you are not running along the corners with a chamfering cutter.

[LeeWay]

I do get burrs Geof mentioned with the full cut.
I just knock them down with a file.
My parts are almost always powder coated anyway, so no problems there for me.

[RICHARD ZASTROW]

photomankc, Kennametal recommended a ratio of 3 (face to be milled) to 5 (effective cutter face). I like to go straight down the middle so the tool marks are the same on each side. LOL

Dick Z

[photomankc]

I guess I'll try to run down the center and see how it goes. I need the brown truck to arrive with my arbor!

[photomankc]

Well the arbor arrived. Experimented and found that raking into the cut was terrible. I got chatter that was aweful. Tried down the center and that was better. Lots less chatter even on steel. Going down the other side climb milling produced the best results. Better than anything else i have been able produce. In aluminum even with the cheap inserts the finish was real nice. Not quite as good in steel but still better than I have been able to do with just a fat endmill.