Interact 412

[besc]

Can anyone help me with a Bridgeport Interact 412? Here is my problem. My Z axis depth of cut varys .005 in a 3.5in travel. So I use a test indicator to run along the top of a 6in parallel and there is no variation. I miked out both paralles in several places and nothing varies more than .0005 if that. Im facing off a piece of alluminum to .200 inches taking only .05 per pass with a 2in end mill. The piece is 1.75 wide and .500 thick to start with. When Im finished one end is .196 thick and the other is .191 thick. The piece is only 3.5 long. I have a precision 2in LED indicator that I have used for years now and it always mikes out to 2.002 and thats where I set my Z coordinat. So the top of the parallels is 0.0. It would be one thing if one end was .200 and the other was .195. But its .196 and .191. Oh and no, there is no play in the parallels. I set them with a dead blow hammer and they are tight when I start. Please help. Thanks. Mike.