The WoodRiver® 3/8" x 4" Steel Forstner Bit Extension adds reach when a standard wood drill bit cannot achieve the required drilling depth. Its compact design increases boring capacity by 2-15/16", allowing deeper holes without switching to a specialty bit.
A precision-fit socket accepts Forstner bits with 3/8" diameter shanks and secures them with two set screws. The set screws are adjusted with a 3 mm hex key, helping maintain a firm connection during operation. A tri-grip shank provides stronger chuck engagement and helps reduce slippage during heavy drilling. Because longer extensions increase leverage, lower drill speeds are recommended to maintain control and help reduce vibration during deep boring applications. For use with Forstner bits 7/8" and larger, the extension expands the versatility of existing shop tooling while maintaining accurate drilling performance.
As part of a collection of drill press accessories and power tool accessories, this extension provides added reach for furniture building, joinery, use on a wood lathe and general woodworking tasks that require deeper bores without sacrificing control.
Features: Adds 2-15/16" of drilling reach Accepts Forstner bits with 3/8" diameter shanks For use with drill bit sizes 7/8" and larger Two set screws secure the bit in the extension socket Set screws require a 3 mm hex key (not included) 3/8" tri-grip shank improves chuck engagement Overall extension length measures 4" Precision-machined steel for durability and accuracy Made in Austria Specifications: Overall Length: 4" Added Reach: 2-15/16" Bit Shank Capacity: 3/8" Minimum Drill Bit Size: 7/8" Shank Size: 3/8" Shank Style: Tri-Grip Set Screw Size: 3 mm What’s Included: (1) WoodRiver 3/8" x 4" Steel Forstner Bit Extension