50mil Wire Wrapping

QA Technology’s 50-mil center sockets and X Probe termination pins can be wire wrapped on .050 [1.27] centers. The recommended wire is a solid 30 AWG Kynar insulated copper wire. Larger diameter wires will cause crowding between adjacent sockets due to the .050 [1.27] center spacing. The recommended strip length (shiner) should be a minimum of .625 [15.90] to achieve the recommended six to seven wire turns with a regular type wrap. Modified wraps are not recommended as the finished diameter exceeds the .050 [1.27] center spacing.

Kynar Heat Shrinkable Tubing

Due to the center spacing, Kynar heat shrinkable 3/64" diameter available from electronic distributors tubing is required on every other connection to prevent adjacent sockets from shorting together. Kynar tubing is stiffer than other types making installation easier. Colored tubing (blue shown) is recommended over clear tubing as it helps identify progress during the wrapping operation.

Recommended Tools

Wire wrap tools designed for .050 [1.27] centers are recommended. With care, tools designed for .075 [1.91] centers are also used on .050 [1.27] centers.

Installation

  • Install sockets into the socket mounting plate at the desired set height with the proper QA installation tools. Slide the Kynar heat shrinkable tubing over the 30 AWG wire. Wire wrap every other socket (Photo 2).
  • Insert the wire into the smaller of the two holes nearest to the outer periphery of the bit until the wire insulation makes contact with the bit face.
  • For a clockwise wrap (as viewed from the top of the socket), make a bend to the left at the nose of the wire wrap tool. Reverse the bend direction for a counterclockwise wrap (Photo 1).
  • Align the center hole on the wrapping tool nose with the post and slide the tool down the post to the desired wrap location. If morethan one wrap is to be made, adjust wrap location accordingly.
  • Anchor the insulated portion of the wire and exert a small amount of pressure on the wire to prevent it from spinning.
  • Trigger the wire wrap gun while using light forward pressure. If the operator presses too hard the result may be over wrapping. If removed too soon, spiral or open wraps may result. Keep the tool on the post until the wrap is completed. Slide the Kynar tubing over the wrapped post, the top of the shrink tubing should be even with the top of the wire wrap post (Photo 3). (optional) Shrink the tubing with a heat gun intended for the purpose, note that the Kynar tubing has a shrink temperature of 175°C (Photo 4). Wire wrap the remaining posts without insulation (Photo 5).

Unwrapping Wire

Remove shrink tubing by slitting it longitudinally with a penknife and pulling it off with long nose pliers. This can be difficult and care must be taken to avoid damage to the wire wrap post. Place the unwrapping tool on terminal/post, use moderate forward pressure and rotate in a direction opposite to the wrap. (Photo 6) Maintain forward pressure until the coil has loosened sufficiently and can be removed by hand.

Photo 1: Tool with wire on .016 [0.41] square post

Tool with wire on .016 [0.41] square post

Photo 2: Every other post has been wrapped

Every other post has been wrapped

Photo 3: Shrink tubing is even with top of post

Shrink tubing is even with top of post

Photo 4: Tubing has been shrunk on posts

Tubing has been shrunk on posts

Photo 5: Finished Assembly


Finished Assembly

Photo 6: Unwrap Tool being used to remove a wire

Unwrap Tool is being used to remove a wire