When building frames, you can select to join them in many ways. I often join them using tenon and mortises. When doing so, I find some situations where I prefer using the Leigh D4R to route the mortises. I have described how to route mortises and achieve a very good fit for the joinery of the bottom or top frame using the Leigh D4R.
For such frames, often you have a left and a right side, and a front and a back frame. Many times the distances from the floor need to be the same, since for example a drawer resting on these need to have the same heigh to sit nice and horisontally in the frame. As I have mentioned, the exact distance is not equally important. If the drawer is 88 millimeter from the top, or 89 millimeter from the top often does not do a big difference to the eye. What does make a big difference is if the four corners differ in height. Thus, repetitively getting the same distance is more important than getting the absolutely perfect measurement. This can be achieved easily witht he help of the Leigh D4R.
We achieve the repetitively same distances by avoiding to measure, and instead focus on transferring the distance. How we transfer the distance does not matter that much and there are many good ways to transfer a distance to a set up. The importance is that it is done in a way where we can easily see or feel if the wanted distance is achieved.
On the picture can be seen how this can be done on the Leigh. It was previously described how to route the mortise at the end, using the vertical wooden stop bit as a reference. On this picture is seen how the very same stop bit is still used as a reference, and as a reference to the very same end on the bit being routed. It is important to keep using the same end of the bit being routed as reference, so errors in measurements do not multiply. Every new measurement starts from the end, thus, previous errors in measurements do not affect the next.
Previously, the inner side of the stop bit was used as reference. In this routing setup, the outer side of the stop bit is used when setting up the piece to be routed.
This means that the thickness of the stop bit (④) has to be adjusted for. It can be done matematically, subtracting the thickness before setting the stop, which works well if you are building from a drawing and using a sliding gauge with a built in scale. However, that kind of calculations often lead to mistakes (adding instead of subtracting or making an error in the calculation). Thus, a good habit is to use another stop bit (⑤) with the same thickness as the stop bit to adjust the measurement. This is easy, place one of the test pieces (③) at the intended final location of the piece to route (①), and then place another piece with the same thickness as the stop bit at the side of that (⑤). Now dial in the distance from edge (②) to that "simulated stop bit".