deep hole drilling machine

Counter Boring Tool

Counter boring reaming tools should not be confused with shallow- hole, counter boring reaming multi-cutter tools or single point boring bars that are used on machining centers or CNC lathes. Sunnen's Finish Boring Reaming tools are generally for bore depths deeper than 7+ times dia. (L/D) and are used to open up existing holes with increased precision, productivity, and versatility. In the majority of cases, one will be able to produce holes with closer tolerances and finer surface finishes, possibly eliminated the need for honing.

Sunnen offers a full line of single indexable insert tipped tools ranging from 12.7 – 711.20 mm (.500″ – 28.000″) diameter. When required, multi-cutter or stepped counter boring reaming tools can be furnished to conform with component design criteria or as roughing tools for subsequent form boring operations.

Push and Pull Style Tools

Push Style Counter Boring Tool Pull Style Counter Boring Tool

Push counter boring tool                                                       Pull counter boring tool

The counter boring reaming tools are also available in both push and pull styles. Pull style tools are the first choice for accurately opening up and straighten an existing hole.


Reaming Tool In addition, our counter boring reaming tools are self-piloting but when concentricity is of the utmost importance. These tools can also be furnished to pilot off the existing bore.

Counter boring reaming tools can be designed and offered as range tools. These tools are designed with deeper pockets which are furnished with adjustable shoes. When an alternate tool diameter is needed, all one has to do is shim the tool out to the new diameter required. In larger diameter tool sizes, it is possible to adjust the tool size up to as much as 19.05 mm (.750″) on diameter.

Sunnen offers specialty multi-cutter pull boring tools for centrifugally cast tubing. These tools are designed to follow the camber of the cast tube while maintaining uniform wall thickness and are they are capable of obtaining feed rates up to 1.27 mm (.050”) per revolution.

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