To sharpen a conventional smooth-rim Forstner bit, clean it, hone the inside of the rim, sharpen the chipper faces, then touch up the centering spur. Use light strokes and preserve the bit’s original angles. Do not file the rim’s outside edge: it determines the hole diameter. Serrated-rim and carbide-tipped designs need different care, so identify the cutting edges before you begin.
Identify the bit before sharpening
Forstner bits do not all cut the same way. A conventional bit has a smooth outer rim, chipper edges inside it, and a centering spur. A serrated-rim bit has sawlike teeth. Some carbide-tipped designs use cutting flutes while the rim mainly guides the bit. The right sharpening surface and tool depend on that construction.
Remove pitch and debris first, then inspect the rim, chippers, and spur. If the cutting arrangement is unclear—especially on a carbide-tipped bit—check the manufacturer’s instructions rather than applying the conventional procedure to every surface. WOOD Magazine’s sharpening guide and Highland Woodworking’s discussion of Forstner-bit designs describe these distinctions.
Sharpen a conventional smooth-rim Forstner bit
- Clean and inspect the bit. Remove pitch and sawdust so you can see the actual edges. Note the original bevels and the relative height of the chippers and rim before removing any metal.
- Hone the inside of the rim. Use a rounded-edge slipstone or half-round stone on the inside surface only, following its existing shape. A coarse stone can remove a dull edge; finish with a fine honing stone. Take off only enough material to restore a clean edge.
- Sharpen the chippers. Hone the cutting faces and bevels while keeping the stone aligned with the original throat and bevel. Preserve the crisp corner where each chipper meets the rim; rounding that junction can make the bit cut less cleanly. Avoid lowering the chippers too far.
- Touch up the centering spur last. Use a fine file with light, even strokes. Apply the same number of strokes to each face so the point remains centered.
Lee Valley’s 2013 instructions for its metric HSS Forstner bits give about 0.005 inches below the rim as an example of the factory relationship between chipper and rim. That is a manufacturer-specific design figure, not a universal specification for every Forstner bit.
Recommended Free Tools
#1 Best Overall
- Drill Bit Tool Sharpener Set: Get your hand tools back to the sharpness you like with our kit. This economical three-piece sharpening tool kit will renew the cutting power of worn-down Forstner bits and more. Perfect for any forstner bit (including carbide-tipped and multi-spurbits)
- Sharpen and Split: The razor-sharp edges of the multi tool blade sharpener have a tough build to cut precisely, sharply, and smoothly. This forstner bit sharpening kit can also be used to touch up saw blades and a variety of drill bits.
- Premium Material: The tool sharpening system made of premium carbide material ensures high-quality sharpening speed and finish. Our sharpening tool kit will keep your router bits performing flawlessly.
- Kit Includes: The blade sharpener kit includes (1) 600 grit diamond honing stone (1) a 600 grit triangular diamond file, (1) Ceramcut honing stone, and Complete Sharpening instructions. Our Forstner Bit Sharpening Kit for wood bits weighs 3.04 ounces.
- Great Gifts for Woodworking: Gift these tools to anyone who works with wood, be it a woodworker, carver, or DIYer to make their work easier. This high-quality Forstner bit sharpening kit will be something they love and use.
Sharpen a serrated-rim bit differently
For sawlike rim teeth, clamp the bit securely and use a small triangular file on the back of each tooth. Make only a few light strokes per tooth, following its existing geometry. Do not substitute the smooth-rim procedure or file the teeth aggressively. Fine Woodworking’s guidance and WOOD Magazine’s instructions both cover triangular-file sharpening for sawlike teeth.
Protect the diameter and cutting geometry
- Leave the outside of the rim alone. It establishes the bit’s diameter, so filing or honing it can change the hole size.
- Keep the original chipper bevels and angles. Align the stone to the existing bevel and throat rather than reshaping them.
- Use minimal, balanced strokes. Excessive removal can alter how the rim and chippers meet; uneven spur filing can move the point off center.
- Do not assume carbide follows the steel-bit method. In some carbide-tipped designs the flutes do the cutting and the rim acts as a guide. Follow the maker’s method or use a sharpening service if the correct abrasive or geometry is uncertain.
Choose hand sharpening or a service
Hand sharpening is most practical when you can clearly identify the cutting edges and hold a stone or file consistently. A professional service is a sensible alternative for valuable, damaged, carbide-tipped, or awkward-to-hold bits. Forrest Manufacturing’s 2024 sharpening price sheet lists service for steel and carbide Forstner bits; the sheet says prices may change, so verify current availability and rates directly.
Quick Recap
Best Value
- Package Includes: you will receive a 35mm Forstner drill bit, a hinge drilling locator, and a hinge hole drill guide template, specifically designed for drilling precise 35mm cup shaped holes with any hand drill for installing concealed cabinet door hinges; Ideal for DIY enthusiasts, woodworkers, and homeowners
- Quality Material: the 35mm Forstner drill bit is made of carbide, ensuring sharp and efficient cutting; The hinge clamp is made of sturdy ABS plastic, capable of withstanding repeated apply without warping or breaking, making it ideal for long term apply in a variety of woodworking projects
- Adjustable Forstner Drill Bits: this cabinet hinge jig features a detachable depth limiter and a transparent scale, making it easy to adjust for different drilling depths; It adopts a center positioning drill bit design, eliminating the need for repeated measurements, re-drilling, and material waste
- Easy to Apply: this hinge drilling guide kit only requires adjusting the template to match the hinge, then clamping and drilling; Ideal for professionals and home users alike, its consistent precision and robust construction make it a reliable site tool
- Wide Applications: our concealed hinge jig kit is designed to fit a wide range of home refurbishments and woodworking projects, making it ideal for kitchen cabinets, bathroom vanities, storage units, and custom furniture; It also works with solid wood and plywood, making it a valuable tool for DIY enthusiasts, woodworkers, and repair technicians
Rank #4
- Package Included: 1 x 35mm Forstner Bit, 1 x Hex Key, 2 x Drill Guide Locators, 1 x Hinge Hole Template, 4 x Mounting Screws (screws are small auxiliary accessories). Lockable depth‑stop collar, please tighten the depth screw before every use
- Fast & Accurate Hole Positioning: Skip tedious manual measuring. This jig accurately centers 35 mm standard hinge cup holes and helps prevent crooked drilling holes, greatly improving your cabinet installation efficiency
- Lightweight & Sturdy Construction: Hard‑alloy drill bit + heavy‑duty thick plastic template. Hand‑held friendly, designed for regular DIY woodworking tasks. NOTE: The template is plastic material, not metal
- Reusable & Rust‑Resistant Components: All metal parts feature anti‑rust performance. The drilling template can be reused repeatedly, reducing waste caused by mis‑drilled wood. Operation steps are displayed on product pictures, no printed paper manual required
- Wide Compatibility: ONLY fits standard 35mm concealed hinge cups for cabinet doors, cupboards and wardrobes. NOT suitable for non‑special‑size or non‑standard hinges. Great for home‑DIY cabinet hinge installation
Rank #3
- Includes: 600 Grit Rectangular Hone
- 600 Grit Triangular Hone
- Ceramic Cone Bit
- Instructions included.
Rank #2
- 【3 ANGLE SHARPENING GUIDES】 Includes three drill bit sharpening guides marked 90°, 118° and 135°, letting you choose the angle suited to different drill bits and sharpening tasks.
- 【SIMPLE MANUAL SHARPENING】 Align the matching guide with your bench grinder, place the drill bit against the guide, and grind along the set angle for a more consistent sharpening process.
- 【STEADIER ANGLE CONTROL】 The shaped guide helps keep the drill bit positioned at the selected angle while grinding, making it easier to repeat the same sharpening angle across multiple bits.
- 【NO ELECTRONICS OR BATTERIES】 This manual guide requires no built-in power, cords or batteries. Use it together with a suitable bench grinder or grinding machine for hands-on control during sharpening.
- 【FOR WORKSHOP & DIY USE】 A practical sharpening aid for woodworkers, machinists, makers and DIY users working in home garages or workshops, helping extend the usable life of dull drill bits.
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
