Pattern for two piece. I will speak in regard to the machine mentioned by you in the first post. The pattern remains the same regardless of machine. For an X-2/Progression 200, due to the thin beam, you would use the thinner mounting adapters (one at head, one at throat). I have never used or strung BHB7, but as a poly, with less stretch there are two important notes when using an X-2/200: 1. The bar (with weight) will normally have to be started closer to horizontal a. either at an angle before inserting and wrapping the string around the rotational gripper before lowering it to horizontal, b. or started down, then inserting/wrapping the string, holding the ratcheting rotational gripper and lifting the bar up to horizontal. The amount of stretch the string has will be learned immediately as you determine, for example, where to place the bar (or amount to "ratchet" up) to get it to horizontal, but not far above. 2. With these Gamma rotational gripper machines there must be enough string to get out of the racquet and around the gripper. This is about 15 inches. This is important when tensioning the final mains. Therefore, you must determine how much BHB7 (which stretches less than say a syn. gut) it takes to reach. Also, in the event it does not reach, you can use a starting clamp to bridge/jump to the gripper to tension. If possible, on a first string job, be generous and measure how much you started with and how much you needed/had left at the end. Of course, you have to have enough of any string to reach the gripper to tension, but polys stretch very little, while some synthetic guts seem like they are stretching forever. Aside from that, after completing BHB7 mains, for example, you may have to adjust the clamp tightness for your different cross string (whatever it may be). You may want to indoctrinate yourself with a full bed of synthetic gut just to get the process down, even if you cut out the free/few $ strings.