BT3100 Rip Fence Rail Alignment

Note:	The rip fence rails have a global impact on the alignment of the machine because so many other features are based upon them. While this is not particularly unusual for a tablesaw, the unique thing about the BT3100 is that these rails are designed to be moveable. When the rails are moved it is quite likely to throw out any fine alignments made to the rip fence and SMT. For this reason, my recommendation is to set the rails in one configuration and leave them set there forever.
Goal:	The rip fence rails should be level with each other and a set height below the main table. The rails should be a constant distance from one another as well. The rails also need to be positioned to give a true reading for the rip fence position since there is no adjustment for this on the rip fence itself.
Tolerance:	The tolerances for this alignment is dictated by the machine feature that is based upon it.
Error Effect:	If the rails are not level with each other, the rip fence and SMT may be at an angle relative to the main table. If the front rail is not positioned to give a true reading for the rip fence, the user will have to take a reading with another measurement device.
Process:	The rails are extruded aluminum components (which tend to be pretty consistent and accurate); they mate to milled bosses on the main table casting. All indications are that they will install very well aligned as long as normal care is used during assembly. The alignment of the rails is relative to the main table. This is pretty narrow and does not provide a lot of measurement resolution if it is used directly. If greater measurement resolution is desired, a straightedge can be clamped to the table to provide a better reference. From this reference the height relative to the main table can be more finely measured. If both rails are at a set height below the main table they should be in plane with it and each other. To check the rail separation distance, a simple rule or tape measure can be used. If there is a discrepancy the only way to correct it would be to shim one of the rails. If this is done, it would be preferable to shim only the back rail. This alignment is not critical and the rails should be fine under normal assembly circumstances. Basically - it isn't worth bothering to align them precisely and it is very unlikely event they would need it. Because the rip fence does not have a moveable cursor, the front rail must be positioned very accurately for the tape to read true. With a little trial and error it is possible to position the rail correctly. However, if a different blade is installed the reading can be off (yes it does matter). It is actually pretty easy to modify the cursor to allow for minor adjustment, that is what I recommend. Repositioning the rip fence rail is too inconvenient and so is using another measuring device.