How to Install a Pre-assembled Tether

This is an alternate method of attaching a tether, where the tether is already assembled at the clip end.
It requires only one figure-8 knot to fix it in place at the spool.
You will be shown how to make a figure-8 knot below.

Do NOT attempt to use an alternative knot. It will fail.

You will need:-

  • an assembled tether, including draw wire, cord, Si tube, magnet and clip
  • 4-5 mm screwdriver
  • tweezers or smooth jaw snipe nose pliers
  • 2.5 mm hex key

The Procedure

Remove the Existing Tether

  1. Remove the spring motor cover
  2. Place the PowerTool on it's feet so that the old cord does not drop behind the motor
  3. Lift the tether away from between the angle sensor and the spool with the hex key.
  4. Remove the old tether from the PowerTool (it will still be attached to the spool)
  5. Turn the PowerTool onto it's end and remove the spool pins
  6. Using the tether, rotate the spool anti-clockwise until it disengages from the arbour
  7. remove the old tether from the spool

Thread the New Tether

  1. Feed the draw-wire of the new tether into the slot and through the angle tube, being careful not to lose the tether from the grip of the draw-wire

    The draw-wire will not feed through the tube without help
  2. Grip the free end with tweezers or pliers and carefully insert it into the tube, 3 - 4 mm should be enough
  3. Pull the grip-wire through the tube until the tether appears
  4. Repeat this process for the spool.
    You will find that the spool hole is smaller than the angle tube which will require a little more effort.
    Be careful not to lose the tether from the grip-wire.
  5. Remove the grip-wire from the tether

The Knot

The tether is fixed to the spool with a Figure-8 Knot, which is an Overhand Knot with a twist.
An Overhand Knot would eventually unravel and let go if used with this chord material, so
   PAY ATTENTION HERE!

An Overhand knot is made by forming a bight (a 'u' shape), taking the tail (the short end) and crossing it over the standing end (the long side), then under the standing end and through the bight from below.

A Figure-8 knot starts the same way, forming a bight, crossing over the standing end, then under the standing end, (and here's the twist) then back up and through the bight from above.

Time to make the Figure-8 knot

  1. Form a bight and cross the tail over the standing end
  2. Then under the standing end
  3. and finally, feed the tail through the bight from the top
  4. Before tightening the knot, adjust it so that it is less than 20 mm from the tail end. Any more and it will begin to cause problems in the spring motor.
      (Best you don't attempt to cut it to length with a pair of scissors. This cord is tough)
  5. Draw the tightened knot back towards the spool and lodge it firmly into the counterbore

Rebuild The PowerTool

  1. Feed the spool onto the spindle and engage the threads
  2. Using 100 - 200 mm of tether, lead the spool clockwise (like you did at the beginning but the other direction) until the top of the spindle is flush with top of the spool.
  3. Continue rotating the spool until the bottom of the thread well is in alignment with the angle tube.
  4. Pull the tether through the angle tube until all is outside of the PowerTool block.


    It will now be obvious if alignment was achieved above. If not:-
    1. snag the tether between spool and angle tube
    2. lift some out
    3. turn the spool until alignment is achieved
    4. Pull the tether through as before

  5. Wind the spool down into the block. This will draw the tether in and wind it onto the spool.
  6. If the spool pulls all of the tether in before it bottoms out on the spring case :-
    1. snag the tether between spool and angle tube
    2. lift some out and take a turn off of the spool, being careful not to drop tether below the spool.
    3. Tighten the tether and use the spool to pull it back in
    4. Repeat until the spool bottoms out and the tether remains slack
  7. Slowly rotate the spool anticlockwise until the pin threads can be seen at the base of the spool pin holes. This should take less than a turn.
  8. Carefully install the spool pins. Do not over-tighten then. Less than 1/8th of a turn once bottomed is more than enough.
  9. Reel out the tether to it's full extent. The top of the spool needs to finish level or just below the top of the spool pins.
      Not above the spool pins!
  10. If the top of the spool is too low :-
    1. Hold the top of the spool from returning with your left index finger
    2. Snag enough tether from the spool side of the angle sensor to loop anticlockwise around the spool.
      You'll have to change grip to pass the tether under your fingers.
      Don't release it!
    3. Pull the tether tight, check the height and repeat as needs be.
      Don't let the top of the spool move above the spool pins.
      Ideally you will have added 2 - 4 turns when done.
  11. Return the tether to find it stopping with some tension on the silicone tube
  12. Replace the springmotor cover