IsoBevel™ Grinder/Sharpener

(U.S. Patent 6,381,862)

The IsoBevel system works with grinders and sharpeners that produce hollow-ground bevels, such as a wet wheel sharpener or a typical high-speed bench grinder.  The system provides users with the ability to rapidly and accurately adjust the grinder’s toolrest to obtain a prescribed bevel angle on the tool, even as the grinding wheel size reduces due to wear.  The objective of this invention was to eliminate the cumbersome and time consuming process involved in setting a grinders toolrest to achieve a prescribed bevel angle on a tool.   Compare the prototype below to any other grinder and I think that you will find that this system provides the fastest and most accurate means for sharpening or shaping many tools in the shop.  The system excels at sharpening chisels, plane blades, lathe tools and even carving gouges.  It is also useful for reshaping damaged tools.

How to Use It

Step 1.  Set pointer length.  This step only has to be performed periodically as the grinding wheel wears down.  It is accomplished by placing a straight edge against the wheel and adjusting the pointer so that the tip touches the straight edge.  Direct measurement of the grinding wheel is never necessary.

Step 2.  Adjust the toolrest to achieve the desired bevel angle by reading the bevel angle indicated by the scale and pointer.




Step 3.  Lock the toolrest to begin sharpening or shaping.


The result is a tool that has been ground the the desired bevel angle.  Since Step 1 does not have to be performed often, the adjustment process takes just a few seconds!


Delta 23-700 Retrofit Kit (IsoBevel Mk. II)

Existing bench grinders and wet wheel sharpeners can be retrofit with the IsoBevel™ system.  Below, one can see a Delta  23-700 Wet/Dry Sharpener that has been retrofit with the IsoBevel™ system.  Link to a PDF Installation and Operation Manual.

Owners of  the Delta 23-700 Wet Wheel grinder can improve the usability and expand the capabilities of  this popular machine.  This retrofit kit replaces the flat toolrest supplied with the Delta grinder with the  IsoBevel system.  The IsoBevel system allows the user to conveniently and accurately set the flat toolrest to achieve a desired bevel angle on a tool even after the grinding wheel wears down.  Most users of the Delta machine know that the 10 inch wet wheel wears fairly rapidly, but with the IsoBevel system, the built-in scale maintains accuracy as the wheel wears down to as small as 8 inches in diameter.   Two machined cast aluminum flat toolrests are included. The large toolrest is of the same dimensions as the original Delta toolrest while the other toolrest is shorter to accommodate chisels with short blades.   The toolrests slide on tough self lubricating UHMW plastic ways that can stand-up to a wet abrasive environment. The UHMW ways are mounted on a machined cast aluminum support.   The tool bevel angle is adjusted using a a leadscrew with left and right handed threads (similar to those used in hand-screw clamps)  to rapidly and precisely adjust the support linkage.  The IsoBevel scale indicates the bevel angle will be ground on the tool for a particular toolrest position and grinding wheel diameter. As the wheel wears, the grinding wheel diameter never has to be measured because the scale's pointer can be adjusted by using a straight edge held against the grinding wheel.  Another great feature of this retrofit kit is that the flat toolrest can be removed from its support rod so that Tormek® jigs can be used with the Delta 23-700.  The support rod has a diameter of 12 mm and is of sufficient length to enable use of a wide variety of Tormek® jigs.  (Note that the IsoBevel scale only works with the supplied flat toolrests and cannot be used when using Tormek® jigs).   

The retrofit kit installs with two bolts and uses the existing tapped holes that secure the original pillow block that supports the end of the grinding wheel spindle (see the bronze bearing in the black plastic pillow block on the far right of the photo below).  No calibration is required since all hardware is secured to a replacement pillow block which automatically ensures proper alignment of the IsoBevel system with your grinding wheels axis of rotation.

Construction Details:
bullet7 Aluminum castings (machined to critical dimensions)
bulletSteel pins and screws: zinc plated or cold blued
bullet2 Flat toolrests (1 large, 1 small) slide on 1/4" UHMW boxslide ways (self lubricating plastic) 
bulletMiter gauge slots compatible with original Delta 23-700 miter gauge.
bulletPositive toolrest adjustment via leadscrew with LH-RH threads
bulletKnurled Aluminum Leadscrew knob
bulletPillow block with bronze bearing and capped oil cup
bulletSnap rings secure pins in linkage
bulletScale professionally printed on aluminum plate (white indicia on black background)
bulletScale and linkage mounted on 3/16" painted steel plate
bullet12 mm toolrest support rod compatible with Tormek® jigs

The retrofit may also fit other grinders similar to the Delta 23-700 such as the Penn State SSG or the Grizzly 1036; however, the unit has not been tested with those machines.  If you are considering this unit for a grinder other than the 23-700, the critical dimensions to check on the spindle support pillow block are as follows: 1/4" Mounting holes 48 mm between centers; Spindle center 16 mm above pillow block mounting surface.  Inside diameter of bearing surface = 16 mm.

 Individuals interested in building their own machine can now purchase scales directly from me at $20 a piece + shipping.   


The IsoBevel™ system is currently available for licensing.  Companies or individuals interested in the right to produce and sell the system in the United States should contact the inventor via email at  Licensees will be provided with a software package that generates IsoBevel™ scales in a format that is compatible with most computer aided drafting packages to aid in the design for manufacturing phase. 

Retrofit Installation and Operation Manual 

Building an IsoBevel Grinder/Sharpener

IsoBevel Scale Generation: Software Manual

Mathematics of the IsoBevel System



Copyright © 2003-2007  David B. Doman, PhD  All rights reserved.

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