CRITERION BORING HEADS
Information Sheet

The Criterion Boring head is a product of many years of development and refinement. The boring head has three main components - the body, the bar holder, and the dial screw.

The body has a black oxide finish for rust prevention and is threaded on the underside to accept a variety of shanks. The two outside-gib screws (DET #5) have been pre-set at the factory to permit easy travel for offset adjustments. The center gib lock screw (DET #6) should be tightened after the proper setting has been established. Because this screw exerts a direct force on the bar holder dovetail, a firm finger-tight pressure is all that is required to lock the bar holder in place during a cut.

To advance even a thousandth or two, we recommend loosening this screw (DET #6) slightly. Then re-tighten after the proper adjustment has been made.

The "DBL" style bar holder (see figure 1) has two boring tool holes and a crosshole. The "s" style bar holder (see figure 2) has one boring tool hole. Both bar holder styles have a satin chrome finish and set screws to hold the boring tools and bars rigid during use. The dial screw is used to move the bar holder along the dovetail of the body and is graduated to provide accurate adjustments of the bar holder. The cutting edge of the boring tool faces away from the dial screw face when inserted correctly in the bar holder. The boring head should never be used with the dial screw head backed out more than 1/32 of an inch past the body. If this occurs, the dial screw will not be threaded into the body far enough to provide required support and rigidity for the bar holder.

This boring head has been designed to give many years of dependable service with a minimum amount of care and maintenance. Periodic maintenance and care should include:

  1. Applying a thin coating of grease to the surface of the dovetail and the dial screw hole and thread.
  2. Chips and other foreign material should be kept out of the dial screw hole and threads and from between the dovetail surfaces.
  3. After prolonged use the dovetail pressure may need to be readjusted. This can be done by tightening the two outside screws only enough to hold the bar holder firmly in place while still permitting it to move when the dial screw is advanced and the lock screw is loose.
DBL (ROUND) STYLE
  1. Bar Holder
  2. Body
  3. Dial Screw
  4. Set Screws (Bar Holder)
  5. Gib Screws
  6. Gib Lock Screw
SQUARE STYLE
  1. Bar Holder
  2. Body
  3. Dial Screw
  4. Set Screw (Bar Holder)
  5. Gib Screws
  6. Gib  Lock Screw
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figure1 figure 2