barfeed

A barfeed is an automatic mechanism that advances a long rod or bar stock through the chuck of a turning machine, pushing the material forward at fixed intervals so that successive parts can be machined without manual handling or repositioning. It sits between the operator and the lathe, holding coiled or straight stock and feeding it in precise increments, typically advancing 2 to 6 inches per cycle depending on the part length and machine setup.

On most production lathes and screw machines, the barfeed mechanism uses a ratchet drive, pneumatic cylinder, or servo motor linked to the machine's spindle. As each part is completed and the chuck opens, the feed advances the bar by one predetermined amount. The operator removes the finished part, and the cycle repeats. For high-volume runs, this eliminates the time cost and handling error of manual stock positioning, which can add seconds per piece across thousands of parts.

Common types and materials

Most barfeeds work with round bar stock ranging from 0.375 to 2 inches in diameter, though some machines accommodate square or hexagonal stock. The feed mechanism itself is usually mounted on the left side of the lathe headstock or integrated into the chuck assembly. Hydraulic and pneumatic versions are most common in older equipment; newer machines often use stepper motors with digital positioning for tighter tolerances on feed distance. Feed accuracy typically holds to plus or minus 0.015 inches.

A barfeed requires properly straightened stock and consistent material diameter to work reliably. Bent bar, scale, or significant runout will jam the mechanism or produce inconsistent part lengths. The feed fingers or collet in the mechanism can wear quickly if stock is contaminated with coolant buildup or if the clamp pressure is too high, causing the bar to slip instead of advance smoothly.

The term barfeed and barfeeder are used interchangeably in the trade, both referring to the same device. You will also hear "bar loader" or "stock advancer," though these are less formal. The device became standard on production screw machines in the mid-20th century and remains essential on any machine running production batches of shaft parts, bushings, or fasteners.