What to expect Tramming Cutting

srfallsallot

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Hi all. Just learning. I do not know what to expect nor what I am looking at. I trammed my PM932 with the device I made attachment 1. As you can see it seems to be very square. Y axis is the same. I trammed my vice it also is the same. My rpm was 1970 feed rate 2.75 in/min. Cutter 2.5' face mill with 4 carbide inserts. The brick is Al from scrap yard one end was badly damaged. I cleaned it up some on the ends . Attachments 2 and 3 show the dimensions as best I can measure. I do not necessarily believe the 4 digit. So what do you think. Is this ok.

The zoomed in attachment 4 shows a pattern of arcs across the whole part. If i take a 123 block and lay that on it with a strong back light a very small gap barely visible shows up in the middle of the arc. Why?

The zoomed in attachment 6 shows a pattern of arcs across the whole part. This is the opposite side of attachment 4. This was done with multiple passes. If i take a 123 block and lay that on it with a strong back light a very small gap barely visible shows up in some of the passes but not all of the arcs. Why?

Thanks for your patience and insight.
 

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Last edited:
If the tool pattern is hollow in the center and the pattern is not cross hatched, it shows that the tram is not set properly, or that there is flexibility in the machine itself, with the force of the cut pushing the spindle out of alignment with the table. Taking light cuts for finish would not, I think, cause that.
What would happen if you just read one indicator and swung it 180 degrees, is the reading the same?
 
.005" cut depth. That is what I thought maybe the tram is not good but it reads .001 or less over 11 inches. Could the head really be that flexible?
 
My first thought was whether the material might be springing after the cut was taken, maybe from the clamping method or as a result of taking the cut off of one side. I know this is more typical in cold rolled stock, but it still crossed my mind.

-frank
 
The Al brick is~ 10" long ~2" thick and ~2.7" wide held in a 5 inch vice with the overhang equal on both ends.
 
Are you absolutely sure your trimming tool is parallel to the table and the indicator and mounting holes are absolutely square to the bar? An easy way to tell is to rotate it 180* and see if the readings are identical. Another way is to set up a test indicator on the table and run it across the bottom of the trimming bar.
 
As you can see in attachment 1 the tramming indicators read zero. Yes the device was zeroed by tuning it 180. It reads the same in the y axis. Many hours learning to tram the mill.
 
Were both indicators zeroed at the exact same spot on the table? In other words zero one indicator and mark the spot on table then rotate tool so other indicator is on same spot and zero it.
 
My guess would be spindle deflection. Either within the spindle bearings maybe the preload or in the tooling. Your holding a 10" piece in a 5" vise so theirs 2.5" of material unsupported and your measuring .002 diff. That's not to bad. Gibs tight table could be lifting with movement of table. What type of inserts are you using molded or ground. I'd be looking for something sharp.
 
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