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Tramming the micro-mill or Sieg X1 milling machine

The process of tramming a Sieg X1 milling machine is one of the most important things you can do. Most beginners do not even realized that you need to tram a mill. If you’ve no previous experience with machine tools, then such things would never occour to you.

So what is the problem? It all comes down to precision. Unless all the components of the milling machine are properly aligned to each other, we cannot rely on the inherent precision of the milling machine. If the parts of the milling machine are out of alignments, this will compromise each part we make on it.

So to get good parts the micro-mill (also known as the Sieg X1 milling machine) must be in good alignment? Yes. However….. The previous paragraph has another interpretation: The micro-mill only needs to be aligned well enough to handle the type of jobs you are throwing at it.

Some home machine shop metalworking workshop owners get very up tight about having everything perfect to the nearest billionth of an inch. A high level of alignment is not always required, and more often than not, impossible to reliably achieve with cheap machine tools like the mini-lathe an micro-mill. In summary, it is important to have your micro-mill properly adjusted, but do not waste the rest of your life trying to get it perfect – get it good enough, but no better.

So, tramming then? Tramming means "to adjust something correctly". If a milling machine is "in tram" then it is properly adjusted. What do we mean by “properly adjusted”? Looking at the micromill well have a milling bed which we can move back and forth, and side to side with the two hand-wheels. We have a motor powering the tool held in the chuck/collet. This can be moved up and down in a vertical fashion. The motor assembly can be moved up and down by the hand wheel at the top for more gross changes, but it is not used during milling operations. At the rear of the mill, we can loosen some bolts and swing the whole machine head and column in an arc to facilitate milling of angles and diagonals.

The first thing you need is a dial test indicator. At a pinch, a plunger type dial indicator will do, but a proper indicator makes for an easier job.

The mounting fingers for my dial test indicator neatly fit into a 10mm collet, so I mount the indicator on the micro-mill spindle in this fashion. Do not turn the machine on, or you are apt to smash the fragile indicator. Lower the head of the micro-mill so that the tip of the indicator is nearly touching the bed, and then adjust it slowly into the bed with the slow motion control. Now adjust the bed back and forth and side to side using the hand-wheels. In a perfect and ideal world, the dial indicator would not move regardless of where you move the milling bed (presuming it is still under the spindle!). If it does move than something is wrong on the mechanism of the bed, and you probably need to adjust and/or lap the gibs. If it only moves by <0.5mm then you are more than ok. The bed of the micro-mill is in tram!

Now try turning the spindle of the micro-mill around by hand. The tip of the dial test indicator will prescribe a circle on the milling bed. Adjust the position of the indicator in the spindle of the micro-mill so that the circle is about 10cm across. Once again the indicator dial should not move. The micro-mill features a moveable head. It is possible to loosen the column supporting nuts and swing the head to one side to mill on a diagonal. This is all very well for milling on a diagonal, but if you want your micro-mill to cut flat and true to the milling bed, then you need to carefully adjust the column until the circling dial indicator shows, by not changing its reading, that the axis of rotation of the spindle is completely perpendicular to the milling bed. This is, in my mind, the most important adjustment, and it should not be out by more than a few thousandths over the sweep of the indicator.

The best way to make small adjustments to the column is to loosen the bolts a very small amount, and then hit to top of the column with a rubber or wooden mallet. As you tighten the the bolts make sure it stays in tram.

There are many other adjustments you can undertake, and tramming a large mill can take a fair bit of time, however, if you check your micro-mill is in tram as as above then you should be ok.

If you are getting frustrated because your micro-mill will not cut nicely, it is worth checking the tram - and it is always worth tramming the micro-mill after it has been first delivered.

To be honest, I have never bothed swinging the column over for diagonal milling, it is too much hassle to get it in tram again.

This is by no means a perfect or complete description of tramming the micro-mill or Sieg X1 milling machine, but I hope it will get you close!