You might recall that last week I took delivery of a brand new Grizzly G0463 Mill/Drill, also known as Sieg X3 or Sieg Small Mill. Once the mill was thoroughly cleaned, lubricated and put back together it was time to tram the column and the spindle. This step is often missed by new machine owners, but without proper alignment the mill will newer be able to produce accurate work. For instance, if the column is not square, center of the spindle (and thus the cutter) will shift in the horizontal plane as the head is lowered, so the dimensions will be off. On the other hand, when the spindle is at an angle, the holes won't be perpendicular to the table and fly cutters will produce concave surfaces. Fortunately, tramming the X3, although a bit fiddly, isn't very difficult and doesn't require any exotic tools. In fact all you would need is a machinists square, a dial test indicator and a way to hold it [the indicator].
Tramming the Column
|Dial Test Indicator attached|
to the mill's head using a mag base
When tramming the Z axis we always want to start by squaring the column and get it as close to perpendicular to X and Y axes as possible. There are several different methods, but my favorite is to use a machinist's square and a dial test indicator. If you don't own an accurate machinist's square, you might get away with a compound square or even a ground angle plate.
The process is as follows:
- Clamp the square to the table so the blade points up and the body is parallel to the X axis.
- Attach the dial test indicator (or a dial indicator) to the head so the tip touches the square's blade.
You will need to sweep the whole length of the blade, so make sure the head's movement isn't obstructed.
- Touch the tip of the indicator to the front edge of the blade and lock both horizontal axes.
- Move the head up so the indicator touches the square a few tens of an inch from the top and zero it out the dial.
- Move the indicator to the bottom of the square and note the offset.
To avoid confusion, let's call counter clockwise movement negative and clockwise – positive.
First we will need to “calibrate” the square, or in other words, figure out how much off it is from 90 degrees. For that we simply turn it 180 degrees along the X axis and repeat the process above. If the indicator measures a different offset, it means the square is a bit off. No worries though, all you need to do is divide the difference between the two offsets and subtract the result from any future measurements.
|To align the column insert shims |
between the flange and the base.
I like to measure the misalignment along both axes first, before shimming the column. Moreover, it's a good idea to measure a few times and average the results to eliminate any flukes. Now that you have initial measurement in your hand its time to align the column. This is done by loosening the four screws at the bottom of the column and inserting shims. There is a dowel pin on each side of the column flange, so you will need to use two shims per side. For instance, if the column is perpendicular to the Y axis but leans to the right, you would use two shims of the same thickness under the right side of the column's base. Likewise, if the column leans forward, you will want to use two shims along the front edge of the base. Please note, unless you used a very short square, the shims will be proportionally thinner than the offset, so you will likely need to experiment (or dig up your trigonometry text book). If you own a torque wrench, this is a perfect occasion to use it as well to minimize any warping due to uneven screw tension.
My column was tilted to the left and forward, so the indicator measured 0.015” on the X axis and about 0.005” on the Y axis. I added 0.010” shim in the far right corner, 0.012” in the right front corner and 0.003” in the front left corner. This got me to perfect zero offset in the Y axis and about 0.0007” offset over 6” in the X axis. The whole process took a bit over an hour, though.
|Dial test indicator mounted to the spindle|
ready to measure head tilt.
Once the column is taken care of, it's time to check and align the head (and thus the spindle). By far the easiest way to tram the column is using a spindle square. If you happen to own a Super X3 mill with a tilting head that you intend to tilt regularly, an import spindle square might be a good idea. Otherwise similar results can be achieved by mounting a dial test indicator to the spindle and swiping across the table. I used a part of my Indicol-style holder, held in a 1/4” collet, since the clamp was too small for X3's spindle. Alternatively you can attach the mag base to the side of spindle or even make a bracket.
When it comes to the head alignment, I like to start with the Y axis, since squaring will require shimming the head and will disturb the X alignment.
The process is similar for both axes, and is as follows:
- Move the indicator to the farthest point of the arch on that particular axis, preload a few thousandths and note the reading.
- Now move it all the way to the opposite side, being careful no to disturb the setup. (i.e. use the top of the spindle etc.)
- Note the difference in reading and proceed with the alignment.
At this point it is possible that the tip won't be touching anymore, if the head is way out of whack. In that case move the head down until you get a few thousandths of preload and repeat the above steps in the opposite direction.
|Before tilting the column, remove the tapered dowel pins|
To align the head in either axis you will need to loosen the four large screws holding it to the column plate. Access to two of those screws is blocked by the motor, which will need to be removed. Additionally, there are two tapered dowel pins, one of each side of the head. They have internal thread. You can use one of the screws that held the control box to pull the pins out.
To square the head with the Y axis you will need to insert some shims between the head and the column plate. For X axis, loosen the bolts so they are barely snug and tap the head with a soft hammer in the appropriate direction.
As you can see, the process isn't really a rocket science. Unless you get lucky, it will take up to a few hours, and will require a lot of re-measurement. In theory you can align the column and the head to be perfectly square, but for my most home shop operation less than a thousandth over 6” is plenty good. Also, please keep in mind that this is not the only method, and there are many other ways to tram the head and the column. Hoss Machine (Daniel) has posted a few really good YouTube videos on tramming the head on his G0704 mill using a variation of Rollie's Dad's method, and there are a few videos by TubalCain that might be helpful as well. No matter which method you use, with some patience you will get your mill to a level of accuracy seen on precision machines costing ten times as much.