TOOLING
Heli-Coil High Speed Steel Drills are supplied in Master Thread Repair Sets(inch and metric) and all Thread Repair Kits except Spark Plug. All drills fit 1/2inch chucks.
DRILL
Drill out the damaged threads using the drill supplied in the kit. Drill to a sufficient depth to accommodate the insert length and the bolt or screw being used.
TAPS
The taps supplied with kits and sets are referred to as STI or Screw Thread Insert taps.
These taps must be used for Heli-Coil repairs.
The STI taps supplied for standard thread repair look like conventional taps and may be used with the same handle as conventional taps.
Taps for Spark Plug applications are known as a piloted reamer tap. These taps have a pilot thread at the front to pull the tap into the hole. The reamer section that follows removes the damaged threads and then the STI portion of the tap cuts the proper thread for the insert. No drilling is required with Heli-Coil spark plug taps.
INSTALLATION TOOLS
There are two types of Heli-Coil tools supplied in kits -threaded mandrel type and prewinder type.
The prewinder tool is supplied in some coarse and all fine thread kits and sets. These inserts must be reduced in diameter before they are threaded into the tapped hole.This is accomplished by winding the insert through a set of threads called a prewinder at the front of the tool. Generally, coarse thread inserts can be installed just as they come from the package so a simple threaded mandrel type tool is supplied in the kit or set.
INSTALL
Install the appropriate length insert from the kit. Use the installation tool supplied in the kit or set. Wind the insert into the hole until the top coil is1/4 to 1/2 turn below the top surface.
TANG REMOVAL
Remove the tang by using the tang break-off rod (when supplied with the kit) or a punch which fits the inside of the insert. Place the punch or rod squarely on the tang and strike sharply.
For insert over 1/2 inch, 12mm, or for spark plug inserts, use long nose pliers. Holding the tang with the pliers, bend it alternately in and out until it comes free.
Note: For Spark Plug repairs, NO drilling is necessary. The Heli-Coil spark plug kit contains a piloted reamer tap.With this tap, the damaged threads are removed and new threads are cut in one continuous operation.
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