:angry:
I'm having a peculiar problem on my bridgeport series 1 mach 3 retrofit. Since a picture is worth a thousand words, I'll start with one.![Click image for larger version.
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The part in the picture is a block of 7075 just after a .025 face mill operation with a 5/8 bit. The part should have a uniform finish. Instead theres a spot where the bit 'dipped' into the part about .0065 and then rose back out just as quickly. Aside from that one little spot, there doesn't seem to be any other inconsistencies in the part.
I've noticed similar problems on other parts. I'll finish a program and there will be an inexplicable dipping of the tool into the part, and it seems to happen around the same spot on the table. This leads me to believe that the problem might be in the table itself, though I imagine that if it were, the problem would manifest itself with more regularity. I have under .001 backlash in the z axis, but if I pry up on it with a big screwdriver I can get another .004. I'm guessing this is from a loose or bad thrust bearing which could also be the problem. But I have a hard time accepting this too. These dips only happen when when the tool is under very little load like during a finish contour or a light face milling operation. The play in thrust bearing requires a great deal or force up or down on the quill.
These are the only two possible explanations I have. But I'm a newby and I'm sure there's something I'm not thinking of. Any and all suggestions are welcome!
I'm having a peculiar problem on my bridgeport series 1 mach 3 retrofit. Since a picture is worth a thousand words, I'll start with one.
The part in the picture is a block of 7075 just after a .025 face mill operation with a 5/8 bit. The part should have a uniform finish. Instead theres a spot where the bit 'dipped' into the part about .0065 and then rose back out just as quickly. Aside from that one little spot, there doesn't seem to be any other inconsistencies in the part.
I've noticed similar problems on other parts. I'll finish a program and there will be an inexplicable dipping of the tool into the part, and it seems to happen around the same spot on the table. This leads me to believe that the problem might be in the table itself, though I imagine that if it were, the problem would manifest itself with more regularity. I have under .001 backlash in the z axis, but if I pry up on it with a big screwdriver I can get another .004. I'm guessing this is from a loose or bad thrust bearing which could also be the problem. But I have a hard time accepting this too. These dips only happen when when the tool is under very little load like during a finish contour or a light face milling operation. The play in thrust bearing requires a great deal or force up or down on the quill.
These are the only two possible explanations I have. But I'm a newby and I'm sure there's something I'm not thinking of. Any and all suggestions are welcome!