Mill Tramming Procedure
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The process of “Tramming” a mill is a calibration procedure typically required if a machinist is new to a machine and unsure of the mill spindle ‘squareness” or verticality to the table, as well as the vise’s parallelism to the machine X axis. It is also a good idea after “hogging” or taking a series of heavy cuts.
This is a multi step procedure that typically requires the bulk of a period to complete the first time, so plan to start early in the period and work diligently until fully complete. (Head and Vice)
This may be an aspect of the practical component of the exam. (TMJ3C and TMJ4E).
The exam tramming will be timed and a level 4 is + or- .002” both axis’ and vise within 30 mins, a level 3 is + or - .002” both axis’ and vise within the full period, a level 2 is + or - .005 one axis within the full period, a level 1 is attempted but incomplete by the period end.
Step one: Loosen the vise hold down nuts with a 7/8” wrench and move it to the left side of the mill table. (You shouldn’t need to lift it completely off unless you need to clean underneath it).
Step two: Loosen, then snug (snug means lightly tightened, about as tight as you can turn an Allen key with the short leg) the socket head set screws for both the front-back axis and the left-right axis.
DO NOT REMOVE THE SCREWS!
Typically, there are a set of screws on the left of the head and a set on the right, sometimes only one on one of the sides like our North Excello, the East machine has 3 either side for the “Y” rotation.
Both have 3 for the “X” rotation.
The “Y” rotation is performed by hand or with a rubber mallet, the “X” rotation is with a 4-sided bolt crank at the front of the ram.
Once you have removed any tool from the spindle and brought the head out of square have this confirmed by the instructor. (Step three)
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Step four: Install a dial indicator in the spindle and manipulate it, (By loosening, adjusting then tightening the black plastic “T” handles on the indicator mount bars) to have the anvil point down and sweep the width of the table. (Start my cranking the table to the “Y” axis center position, that is where the spindle lines up with the center T nut slot) Spin it back and forth a few times to get it correctly adjusted.
A good practice for a beginner is not to start with the indicator contacting the table, but leave it slightly above and see if you can tell which side is higher and which lower. Get your head down to the table level and sight it by eye.
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Step five: Now knock the head back or front (depending on which way it is out) with a rubber mallet. This gets it in the ‘ball park’ so that when you do bring the indicator into contact with the table there will only be .010” or .020” swing on the clock.
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Once you get it within + or - .002” lock up the screws for the “Y” axis. Step six.
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Step seven: Do the same with the “X” axis, remember that on our EX-CELL-O’s this axis uses the crank handle to adjust it.
Once both head rotations are within the .002” tolerance the head is calibrated. Show the instructor.
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Step eight: Next is the vice.
Readjust the indicator mount bars to point roughly horizontally away from you and bring the vise back to the center of the table.
Running the indicator anvil back and forth against the back (fixed) side of the vice get ùse the rubber mallet to then get it within .002”
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Step nine: Lock up the nuts. Show the instructor.