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- Feb 1, 2015
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The first thing that I would do would be to check the gib adjustment as loose gibs can cause lifting of the table in extreme positions.
I would mount a dial or test indicator in the spindle and sweep the table surface in the direction parallel to the vise jaws. You should not see a significant change in the reading. If you do, it indicates that the table surface is not parallel to the ways. Assuming that you see no change in the reading, next sweep a parallel as described by Mitch. If you see a change in the reading there, the problem is in the vise.
The case of the table surface being non parallel to the ways can be cured in two ways. The first would be to resurface the table. Since the mill wouldnt be able to access the entire surface, the table would have to be removed and resurfaced externally. A second cure would be to mount an intermediate plate and mill the surface with a small diameter end mill rather than a facing tool to minimize any effect of poor tramming. This surface should be true to the ways.
A vise can be trued to an certain extent by inverting the vise with a large piece of uniform thickness stock clamped in the jaws. A 2-4-6 block is a good candidate. Seat the block firmly in the vise, tapping with a soft faced hammer and invert the assembly. clamp the block to the table with toe clamps or other suitable means. Mill the bottom surface of the vise using a smaller diameter end mill. Note that if the table surface isn't parallel to the ways, this procedure would worsen the condition so make sure that the table is true first.
I would mount a dial or test indicator in the spindle and sweep the table surface in the direction parallel to the vise jaws. You should not see a significant change in the reading. If you do, it indicates that the table surface is not parallel to the ways. Assuming that you see no change in the reading, next sweep a parallel as described by Mitch. If you see a change in the reading there, the problem is in the vise.
The case of the table surface being non parallel to the ways can be cured in two ways. The first would be to resurface the table. Since the mill wouldnt be able to access the entire surface, the table would have to be removed and resurfaced externally. A second cure would be to mount an intermediate plate and mill the surface with a small diameter end mill rather than a facing tool to minimize any effect of poor tramming. This surface should be true to the ways.
A vise can be trued to an certain extent by inverting the vise with a large piece of uniform thickness stock clamped in the jaws. A 2-4-6 block is a good candidate. Seat the block firmly in the vise, tapping with a soft faced hammer and invert the assembly. clamp the block to the table with toe clamps or other suitable means. Mill the bottom surface of the vise using a smaller diameter end mill. Note that if the table surface isn't parallel to the ways, this procedure would worsen the condition so make sure that the table is true first.