To start this process, the spindle should be loosely installed on the turret using (4) M3x50 socket head screws. Before tramming the spindle, you will need to get the bed very level in the region where you will sweep the dial indicator.
In settings/system editor, open the bed.g file and adjust the area for the mesh grid to the following:
M557 X-60:60 Y-60:60 S60:60
Note: you can comment out the standard bed mesh command by putting a semicolon in front of the line, eg ";M557 X-180:180 Y-90:90 S90:90"
In your machine control screen, now click "Auto Bed Compensation." If the height map does not automatically appear, click the drop down next to "Auto Bed Compensation" and select "Show Mesh Grid Height map." You will then see a false color plot like the image below. In this case, you can see in the data of the chart that the front left corner of the bed is 0.278mm too high. Note: hover the cursor over the specific points on the chart to see the coordinate values.
Install the M4 Thumb screws in the 4 corners as shown. When these thumb screws are tightened, they will push the bed-mount-pin down which will lift that corner of the bed up. However, before the bed-mount-pin can be moved, the clamping screw in the bed needs to be loosened.
Going back to our specific example, we want to drop the front left corner of the bed down by ~.28mm. So, we will first tighten the thumb screw so that it is snug against the bed-mount-pin, then we loosen the clamping screw (this way we don't loose our known location). Now, since we want the bed to drop down at this point, we'll loosen the thumb screw a set amount while pushing lightly down on the bed. Retighten the clamping screw while still pushing on the bed. Because the thumb screw has a 0.7mm pitch, we know to loosen it by ~0.4 revolutions (=0.28/0.7). Note, it is helpful to make a mark on the thumb screw with a sharpie to keep track of its position.
To test the result, click "Auto Bed Compensation."
The result is improved, but we're not quite there. Note: the front left corner does not look like it moved significantly, but this is because the zero point also shifted. It is also helpful to rotate the map to get a better idea of the situation. Now we can see that the front of the bed needs to come down. (We could also lift up the back corners to achieve the same result). After 2 more rounds of adjust-measure-adjust-measure, the bed is level enough to proceed with tramming the spindle. WARNING: REMOVE THE BED LEVEL THUMB SCREWS BEFORE STARTING ANY PRINT OR MILLING CYCLE.
To get started tramming the spindle, move the machine up 50mm in Z and to X=0, Y=0. Install a long tool or 1/8" gauge pin in the collet. Torque the spindle drawbar to ~8in-lbs using a 7mm wrench on the drawbar and a 10mm wrench on the collet receiver. The spindle drawbar is an M3 thread...DO NOT OVER-TORQUE
Use a small machinist's square or a gauge block to get the tool roughly vertical with respect to the bed. It is helpful to have a light source behind the tool to see the gap. See the images below to understand the 2 directions that the spindle can be adjusted.
After getting the spindle roughly aligned using a square or fixture block, install a dial indicator and sweep the bed surface. Make sure your indicator mount has a 1/8" arbor. Do not clamp any tool with a shank diameter less than .120" or greater than .1255" the collet. Carefully loosen the spindle mount and adjust in each plane until the deviation is acceptable. We typically tram our spindles to within .004" over a 4" diameter indicated circle (~.1mm/100mm). When finished with adjustment, re-torque the (6) M3-LOW socket head screws on the sides of the spindle to 6in-lb. Torque the (4) M3x30 socket head screws on the front of the spindle to 10in-lb.
NOTE: If you have a machine with a serial number <25, your spindles will only have adjustment in the yz plane. XZ is taken care of with shims and initial calibration. Please contact us if you would like to upgrade to the fully-trammable design.