How to Re-Thread a Stripped Bolt Hole

  1. Start by finding the correct measurements. Determine the size and depth of the thread that you want (i.e., what size screw will go into the hole?). Forney Industries recommends referring to a technical publication to find the correct measurements.
  2. Place the part containing the internal thread in a vise or clamp it to a table in order to keep it straight and still.
  3. Drill the hole to the correct diameter and depth.
  4. Clean out any debris from the hole. This can be done using a vacuum or simply by flipping the part over and tapping out the shavings.
  5. Insert your tap into a tap wrench.
  6. Apply a few drops of cutting fluid to the cutting part of the tap.
  7. Hold the tap in line with the hole, press it downward and turn it clockwise. Keep it as straight as you can while you turn the tap wrench.
  8. Do not try to re-thread the entire hole in one try. Rotate the tap wrench a few turns then back it off one full turn. This will dislodge any debris. Re-apply cutting fluid throughout the process. Continue this process until you’ve reached the required depth, back the tap out, and clean out any debris.
  9. Test the hole with a new bolt.
IP Cutting Tools
IP Cutting Tools
IP Cutting Tools
IP Cutting Tools

How to Re-thread a Stripped Bolt

  1. Start by finding the correct measurements. You will need to find the diameter of the re-threading die as well as the depth of the thread you will need. Forney Industries recommends referring to a technical publication to find the correct measurements.
  2. Clamp the bolt in a vise in order to keep it straight and still.
  3. Apply a few drops of cutting fluid to the bolt.
  4. Place the re-threading die in a die wrench and slide it on the bolt. Do not try to re-thread the entire bolt in one try. Rotate the re-threading die a few turns then back it off one full turn. This will dislodge any debris from the teeth. Re-apply cutting oil throughout the process. Continue this process until the bolt comes past the top of the die.
  5. Test the bolt.
IP Cutting Tools
IP Cutting Tools
IP Cutting Tools
IP Cutting Tools

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