Tinning is the practice of wetting a surface with solder. In this context, it is the wetting of the exposed conductors, which is recommended as loose strands can inadvertently cause short circuits and are inherently more difficult to control than a single cohesive unit.
All of the butt joints on the MOST Delta are located on the end effector where the heating resistor leads are connected to the power conductors and the thermistor leads and fan are connected to copper pairs. A "third hand" (either literal or the tool) greatly facilitates butt joining.
Tin the conductors per instructions above.
Place adequate lengths of heat shrink tubing over one of the conductors and push it away from the solder joint so it doesn't shrink during soldering.
Align the tinned conductor with the conductor it is to be joined with such that the two are parallel and touching.
Solder the joint and blow on it to rapidly solidify the solder.
Slide the heat shrink tubing over the joint and overlapping insulators on both sides of the joint. Shrink the tube in place.
The limit switches have three terminals, one is common and the other two are normally open or normally closed. The controller firmware expects normally closed, which requires the conductors be soldered to the outermost two terminals, leaving the center terminal alone. Again, a "third hand" is helpful.
Tin the conductors per the instructions above.
Place a small solder puddle on the two outermost terminals of the limit switch.
Place adequate lengths of heat shrink tubing over the conductors and push it away from the solder joint so it doesn't shrink during soldering.
Soldering limit switch.
Solder the conductors to the terminals at the puddles of solder. Blow on the joints to rapidly solidify the solder.
Heat shrink tubing on limit switch.
Slide the heat shrink tubing over the terminal and shrink in place.