Why does the face milling cutter cut unevenly?

[HMF]

CDCO 2.5" indexable face milling cutter.

When a cut is made, the cutter will cut deeper on the left side of the cut.
Cutting left to right, the trailing side cuts deeper than the leading side. Cutting right to left, the opposite happens.
This is most noticeable after all the material has been removed to level out the face being cut.
It doesn't matter how deep a cut is being taken.
Cuts are 2 or 3 thousand per cut.
The mill vise and it is out by 0.001" across the 5" of the vise jaws.

Is the mill out of tram, or is there another problem?


:tiphat:Nelson

http://www.hobby-machinist.com/newreply.php?do=newreply&p=730688​

 

[mitsue]

CDCO 2.5" indexable face milling cutter.

When a cut is made, the cutter will cut deeper on the left side of the cut.
Cutting left to right, the trailing side cuts deeper than the leading side. Cutting right to left, the opposite happens.

Are you changing from climb to conventional milling when you change direction or are you milling on the other side of the part? If you were per say climb milling both directions and the opposite happens I would check the tram. If it stayed deeper on the leading edge I wuld check for play/deflection in the cutter or spindle.

If you can check the tram, spindle side deflection and endplay would help.
Darcy

P.S. Maybe check for table lift on the y axis. I always lock down any non travel axis tight when feeding.

 

[irishwoodsman]

check your cutter, other members are saying cdco sells 2nds on some tools and it maybe the cutter,:thinking:

 

[Tony Wells]

If your cuts are only 0.002/0/003 in depth, cutter deflection is unlikely. When you say "Cutting right to left, the opposite happens.", what do you mean? Does the trailing edge still cut? As in the trailing edge always cuts no matter which direction you go? That normally points to spindle squareness, but not in both directions. If it only seems to cut after the leading edge gets off the work, then seems to dive in, that is likely spindle bearings allowing the cutter to drop a bit. How much is it cutting? Does this happen if you go right back across the surface with no adjustments in Z depth?

 

[Tom Griffin]

Are you saying the cutter always cuts deeper on the right side? If so, the head is rotated slightly clockwise from vertical. Time for a re-alignment.

Tom

 

[Kevin45]

You have wear in the mill. When your leading edge is hitting, you are getting just enough flex (play) that the trailing edge is picking it back up. That is why you are seeing it going the other way also. It only takes a few tenths of play, but with the quill down it magnifies the problem. What you want to do is re-tram your mill and get it as close to dead nuts as you can. Then when cutting, always cut from the same direction until you have the top of the piece faced off. It takes a little more time, but will insure a flatter part. If I have that problem on a particular mill, I try to use a flycutter that will go across the complete piece so I don't get the "stepped" effect. I then turn the piece over, leaving the same edge against the stationary jaw and do the same thing. If the part is too big to cut all at once, then it goes to the surface grinder to insure flatness.

 

[donthack]

Tram the head first, next check your bearings adjustment. Assuming that your quill is always at the same position. Hope I setting the right course.