Mill Leaving Ridges While Face Milling

Tramming the table top does not necessarily mean that you will not get a ridge when moving during milling. If the table top and the ways are not parallel you will get a ridge when moving because the table will actually rise or lower depending on the direction moved. So if you tram your head and still can't get things milled without a ridge or step that is probably the cause. This happens more so on used or rebuilt machines when worn or rebuilt improperly.
 
Your also sposed to tram the head In the y direction .0005 low in the front to account for the deflection said earlier....
 
Also I'll say this, when I tram closer than that if I run a 1 inch face mill there is zero ridge, you can see the stepover but can't feel it, put in the 3 inch, and you can now feel it, couple tenths high on the stepover... the bigger the tool the more tool pressure and the more lift/deflection it will cause
 
You never mentioned the kind of mill you have? If you are making NASA parts then I would get a surface grinder. A milling machine operation will leave tool marks, cannot be helped. The tool marks will be governed by machine rigidity, type of material, type of cutter, machine alignment (being discussed), operator finesse, AND? A good rule of thumb to check your X tram/allignment while making a cut is to look at the cutter in action. Note the forward front of the cut and then see if you have a trailing cut at the rear. The trailing cut at the rear should just be a whisper. So the cutters finish will look like it has a cross hatch kinda pattern with both the forward and trailing cuts even in appearance…Good Luck, Dave.
 
Here's anther example of said cross hatch, btw that's a brick of 7075 alum, and I'm using a hand ground hss insert on a boring head fly cutter setup
20160111_235421.jpg
 
chevydyl said:
Your also sposed to tram the head In the y direction .0005 low in the front to account for the deflection said earlier....
Click to expand...

This may be true for a manual mill where you would preferentially machine in one direction. A CNC machine program runs in all four directions of the table so it is not possible to correct for tool deflection in this manner.
 
True rj, I tram perfect zeros cause of that, and leave stock for light finish cuts to clean it all up, accounting for deflection of roughing
 
Thanks for all the suggestions guys. Messed with it some this morning and I do believe I have a spindle bearing or to that's gone. I still got the same results no matter what I tried. Sometimes it's more noticeable than others. It's not just a face mill that leaves this a end mill will do the same thing. So just to be on the safe side I'm going to check the bearings in the spindle to make sure somethings not going on there.
-Chris
 
Sounds alot like the alignment of the ways is off, that will never go away until you scrape it in
 
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