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Purpose

FireBolts, a term coined by the Team, are 1/4-20 bolts with E-matches glued in. They are used in Tender Descender modifications and also to ignite pyrotechnically operated pistons on the Team.

Fabrication

FireBolt fabrication is simple. First, purchase 1/4-20 stainless steel machine head cap screws. One by one, perform the following procedure:

  1. Secure the bolt in the chuck (preferably a collet chuck for a 1/4-20 screw) of a lathe (head end pointing outward).
  2. Using a center drill, create an indentation in the cap.
  3. Using a 8-32 tap drill size (size 29), slowly drill through the bolt. Use coolant or oil to prevent overheating of the drill bit or part.
    1. During the initial production round, we used a speed of 400 RPM and a feed of about 0.001" per 1-2 seconds.
    2. Drill approximately halfway through the bolt, bring the drill bit out, re-oil it, and continue drilling.
    3. Do not let the drill bit sit inside the screw without moving it.
  4. Tap the hole with an 8-32 tap. 
    1. Turn OFF the lathe.
    2. Replace the drill bit with a center. 
    3. Tap through the bolt with good form. 

      5.  After removing the bolt from the chuck, secure it in a pair of pliers.
      6. Use a grinder (or a drill press with appropriate mounting) to de-burr the end of the screws, which may have sharp pieces poking out of them.

     5. Glue 1-2 E-matches into the hole such that the E-match heads are on the opposite side as the screw head. (Details to be added later)

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