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This will help you create larger diameter starter holes or help when you need to drill in just a little further than the standard bit length will allow. This means the set screws may protrude outwardly from the collet. The reason this is important is that as we mentioned earlier, some bits may have slightly different shank sizes.
Contractors use the extension when they need to bore deep holes for running cables or wires and they also use it for joining larger timbers. It is designed to be used with forstner bits only. Drilling with forstner bits to achieve a flat bottom hole or to start a deep hole turning project like on a larger vase or vessel is essentially impossible with a standard length forstner bit. Forstner bits and Machinery shown in pictures are NOT included. The forstner bit extension gives you additional 5-5/8 inches of reach to bore deeper into your projects.


To remedy this issue we have developed an extra long, heavy duty steel extension that allows you to secure a 3/8 inch shank forstner bit into the end collet. The forstner bit extender is made from solid, heavy duty machined steel.
If you measure your bit shank and it is 3/8 inch, your bit should fit once the set screws are loosened. The collet outside diameter is 25/32 inch without the set screws protruding outward. It is designed to be used with forstner bits only. Please note that some forstner bit manufacturers produce bits that say 3/8 inch shank size when in fact they are not. This means the set screws may protrude outwardly from the collet.



This means that the 3/8” extension will accept 3/8” shank forstner bits while the ½” extension will accept ½” shank forstner bits. With the 10” long forstner bit extension you can now add over 8” of extra drilling depth to your current forstner bits! That alone makes this extension especially ideal for woodturners when having to hollow out large vessels or objects like salt and pepper shakers.
The extension also works great for rustic furniture, joining wide timbers, wooden beverage mugs and even works great on things like turned kaleidoscopes. The extensions will work with hex shank or round shank forstner bits. 10” long by 3/8” extension has an inner diameter of 3/8” and an outer diameter of ¾” and works with bits 25/32” in diameter or larger. To be certain, please make sure your bits fall into the correct socket size before purchasing. Can be used with hand drill as well.


Woodriver is proudly made by woodcraft, routers, woodcraft and Woodcraft Magazine as well as the greatest selection of woodworking books, wood, wood stain and paint, hand tools, kits, videos, dust collection and more.

Our award winning family of brands includes woodriver, wood stain and paint, planes, routers, power tools, America’s leading supplier of saws, wood, sanding, Highpoint, hand tools, Woodcraft and Woodcraft Magazine as well as the greatest selection of woodworking books, and plans.

1. Fulton
#ad
Carpentry and Construction, Fulton 6 inch Long Forstner Bit Extension for Adding Over 5-5/8 inches of Drilling Depth to Your Forstner Bit. for Wood Turners, Furniture
#adFulton #ad - The forstner bit extender is made from solid, heavy duty machined steel. To remedy this issue we have developed a heavy duty steel extension that allows you to secure a 3/8 inch shank forstner bit into the end collet. If you measure your bit shank and it is 3/8 inch, your bit should fit once the set screws are loosened.This will help you create larger diameter starter holes or help when you need to drill in just a little further than the standard bit length will allow. This means the set screws may protrude outwardly from the collet. The reason this is important is that as we mentioned earlier, some bits may have slightly different shank sizes.
More information #ad
The collet inside diameter is 3/8 inch. This tolerance is very tight and designed to accept forstner bits with shank sizes of 3/8 inch or slightly smaller. Please note that some forstner bit manufacturers produce bits that say 3/8 inch shank size when in fact they are not. Contractors use the extension when they need to bore deep holes for running cables or wires and they also use it for joining larger timbers. It is designed to be used with forstner bits only. Drilling with forstner bits to achieve a flat bottom hole or to start a deep hole turning project like on a larger vase or vessel is essentially impossible with a standard length forstner bit. Forstner bits and Machinery shown in pictures are NOT included. The forstner bit extension gives you additional 5-5/8 inches of reach to bore deeper into your projects.
Brand | Fulton #ad |
Manufacturer | Fulton Woodworking Tools and Accessories #ad |
Part Number | 927 |
More information #ad
2. IVY Classic
#ad
High Carbon Steel, IVY Classic 46152 4-Inch Forstner Bit Extension, 1/Tube
#adIVY Classic #ad - High-carbon steel construction, precision ground and polished. Shank: 3/8-inch, length: 4-inch. To fasten the shank in place, use the hex key to tighten these screws.More information #ad
Extends any forstner shank bit an additional 4 inches, Swift Bore Registered Trademark. Ideal for use with any 3/8" shank bit. Two set screws and hex key included.Brand | IVY Classic #ad |
Manufacturer | IVY Classic Industries #ad |
Height | 0.63 Inches |
Length | 4 Inches |
Weight | 0.03 Pounds |
Width | 0.63 Inches |
Part Number | 46152 |
Model | 46152 |
More information #ad
3. Fulton
#ad
Fulton 10 inch Long Forstner Bit Extension for Adding Over 8" of Drilling Depth to Your Forstner Bit Ideal for Wood Turners Furniture Carpentry and Construction 3/8 inch Collet
#adFulton #ad - Forstner bits and Machinery shown in pictures are NOT included. This tolerance is very tight and designed to accept forstner bits with shank sizes of 3/8 inch or slightly smaller. This will help you create larger diameter starter holes or help when you need to drill in just a little further than the standard bit length will allow.To remedy this issue we have developed an extra long, heavy duty steel extension that allows you to secure a 3/8 inch shank forstner bit into the end collet. The forstner bit extender is made from solid, heavy duty machined steel.
More information #ad
The forstner bit extension gives you additional 8-1/2 inches of reach to bore deeper into your projects. The minimum size hole this extension will allow you to drill is 13/16 inch. Contractors use the extension when they need to bore deep holes for running cables or wires and they also use it for joining larger timbers. If you measure your bit shank and it is 3/8 inch, your bit should fit once the set screws are loosened. The collet outside diameter is 25/32 inch without the set screws protruding outward. It is designed to be used with forstner bits only. Please note that some forstner bit manufacturers produce bits that say 3/8 inch shank size when in fact they are not. This means the set screws may protrude outwardly from the collet.
Brand | Fulton #ad |
Manufacturer | Peachtree Woodworking Supply Inc. #ad |
Part Number | 200-2206 |
Model | 2206 |
More information #ad
4. Century Drill & Tool
#ad
3/8" Shank, Century Drill & Tool 38112 12" Ship Auger Extension
#adCentury Drill & Tool #ad - Securely grips ship auger drill bits for extended length. For use with ship auger bits with 3/8” hex shanks. Extension’s shank fits ½" drill chucks. 12" length.More information #ad
Brand | Century Drill & Tool #ad |
Manufacturer | Century Drill & Tool Corp #ad |
Height | 0.75 Inches |
Length | 12 Inches |
Weight | 0.35 Pounds |
Width | 0.75 Inches |
Part Number | 38112 |
Model | 38112 |
More information #ad
5. Taytools
#ad
Taytools 774403 6-3/4 inch Round Shank Forstner Drill Bit Extension for 3/8 Inch Round or Hex Shafts
#adTaytools #ad - Overall length 6-3/4 inches and adds up to 5-5/8 inches of drilling depth. Can be used in a hand drill, drill press or lathe. This round shank forstner bit extension will extend the reach of any Forstner bit 3/4 inch and larger with a 3/8” hex or round shank.More information #ad
Note: will fit auger bits. Contains two set screws for a secure grip on bits. Hex wrench included. Made from precision machined steel. Hole opening is. 375 inches and hole depth 1-3/8 inches.Brand | Taytools #ad |
Manufacturer | Taylor Toolworks #ad |
Part Number | 774403 |
More information #ad
6. Peachtree Woodworking Supply
#ad
Furniture, 10” Long Forstner Bit Extension for Adding Over 8" of Drilling Depth to Your Forstner Bit. for Wood Turners, Carpentry and Construction Use 10" x 3/8" Extension for 3/8" Forstner Bits
#adPeachtree Woodworking Supply #ad - Worse yet, even with a standard length extension you’ll probably only add about 3” of depth to your bit. Drilling with forstner bits to achieve a flat bottom hole or to start a deep hole turning project like a large vase or vessel can be very challenging with a standard length forstner bit. The 10” forstner bit extensions are made from heavy duty solid machined steel and feature a 3/16” thick socket wall to firmly hold the bits in place.This means that the 3/8” extension will accept 3/8” shank forstner bits while the ½” extension will accept ½” shank forstner bits. With the 10” long forstner bit extension you can now add over 8” of extra drilling depth to your current forstner bits! That alone makes this extension especially ideal for woodturners when having to hollow out large vessels or objects like salt and pepper shakers.
More information #ad
This is often not enough of a depth for many of your projects and it can get quite frustrating without the proper tools. The extension also works great for rustic furniture, joining wide timbers, wooden beverage mugs and even works great on things like turned kaleidoscopes. The extensions will work with hex shank or round shank forstner bits. 10” long by 3/8” extension has an inner diameter of 3/8” and an outer diameter of ¾” and works with bits 25/32” in diameter or larger. To be certain, please make sure your bits fall into the correct socket size before purchasing. Can be used with hand drill as well.
Brand | Peachtree Woodworking Supply #ad |
Manufacturer | Peachtree Woodworking Supply inc. #ad |
More information #ad
7. Alfa Tools
#ad
Alfa Tools FB61492 3/8 x 5 1/8" Forstner Bit Extension
#adAlfa Tools #ad - Quantity - 1 per Pack. Forstner Bit Extension Shank. 3/8-inch barrel Inside Diameter. 5-1/8-inch overall Length, 3/8-inch Shank. Premium quality design.More information #ad
Brand | Alfa Tools #ad |
Manufacturer | Alfa Tools #ad |
Height | 0.63 Inches |
Length | 5.13 Inches |
Weight | 0.06 Pounds |
Width | 0.63 Inches |
Part Number | FB61492 |
Model | FB61492 |
More information #ad
8. WOODRIVER
#ad
Forstner Bit Extension 3/8" x 10"
#adWOODRIVER #ad - Our award winning family of brands includes WoodRiver, Highpoint, power tools, sanding, planes, America’s leading supplier of saws, and plans.Woodriver is proudly made by woodcraft, routers, woodcraft and Woodcraft Magazine as well as the greatest selection of woodworking books, wood, wood stain and paint, hand tools, kits, videos, dust collection and more.
More information #ad
Designed for use with WoodRiver forstner bits only. Socket accepts forstner bits with 3/8” diameter shanks. Extension adds 10” to length of forstner bit. Forstner bit held in extension socket with two set screws - 3/8” diameter drive shank allows use of multiple extensions.Brand | WOODRIVER #ad |
Manufacturer | Woodcraft Supply #ad |
Height | 0.85 Inches |
Length | 11 Inches |
Weight | 0.45 Pounds |
Width | 1.9 Inches |
Part Number | 147999W |
More information #ad
9. WOODRIVER
#ad
Forstner Bit Extension, 3/8" x 4"
#adWOODRIVER #ad - Extension adds 4” to length of forstner bit. Socket accepts forstner bits with 3/8” diameter shanks. Forstner bit held in extension socket with two set screws - 3/8” diameter drive shank allows use of multiple extensions.Our award winning family of brands includes woodriver, wood stain and paint, planes, routers, power tools, America’s leading supplier of saws, wood, sanding, Highpoint, hand tools, Woodcraft and Woodcraft Magazine as well as the greatest selection of woodworking books, and plans.
More information #ad
Designed for use with WoodRiver forstner bits only. Woodriver is proudly made by woodcraft, videos, kits, dust collection and more.Brand | WOODRIVER #ad |
Manufacturer | Woodcraft Supply #ad |
Height | 0.8 Inches |
Length | 5.15 Inches |
Weight | 0.26 Pounds |
Width | 2.35 Inches |
Part Number | 145705W |
More information #ad
10. Alfa Tools
#ad
Alfa Tools FB61490 5/16 x 5" Forstner Bit Extension
#adAlfa Tools #ad - Forstner Bit Extension Shank. Quantity - 1 per Pack. 5-inch overall Length, 3/8-inch Shank. 5/16-inch barrel Inside Diameter. Premium quality design.More information #ad
Brand | Alfa Tools #ad |
Manufacturer | Alfa Tools #ad |
Height | 0.63 Inches |
Length | 5 Inches |
Width | 0.63 Inches |
Part Number | FB61490 |
Model | FB61490 |
More information #ad