Carbide Insert RH 55° 3/8″ Boring Bar w/2 Flats

Sherline’s gang-tooling tool post (P/N 5930) was specifically designed for customers converting their Sherline lathe into a chucker-style or gang-tooling lathe. Since most parts produced on a chucker lathe are 1/2″ (13 mm) in diameter or smaller, and the center-to-center spacing on our gang-tooling post is 1.5″ (38 mm), we identified a practical opportunity: our boring bars can double as both boring and outside diameter (O.D.) turning tools.

To support this dual use, we modified our standard boring bars by adding a second locating flat. This allows them to be mounted with the insert face up or face down, providing flexibility for front- or back-side operations. For example, right-hand 80° and 55° boring bars can now be used effectively on either side of the part (see Figure 1).

These 3/8″ diameter boring bars are designed to hold a 2-sided 55° carbide insert, secured with a Torx® screw. Each holder includes an 55° carbide insert and a Torx driver.

• Each holder is 3-1/4″ long and can bore to a depth of just over 2″ when secured with two set screws.

• Constructed from 1144 Stressproof® steel with a black oxide finish for strength and corrosion resistance.

See instructions below for additional guidance on using two-flat boring bars with gang tooling setups.

Pro Tip: Consider using the boring bar with the insert face down to help reduce chip buildup on the insert during cutting. This orientation can improve chip evacuation and extend insert life.

FIGURE 1—55° boring bars used as examples. The left-hand tools are used as turning tools, while the right-hand tools are used as boring tools.

Note: The straight-groove chip breaker shown in some older images is no longer available. Current inserts feature the spider web-style chip breaker as shown here