Wet Or Dry, Coarse Grind to Hone, Instant Grit Change, with Sharpening Jigs

Sharpening System

Wet or Dry, Coarse grind to Hone, Instant grit change, with sharpening jigs.

by David Reed Smith

Download Free Plans from www.DavidReedSmith.com

Costs about $250 to make

Introduction

Sharper is Better

A magnified view of a roughing gouge straight from a bench grinder. / A roughing gouge sharpened on my system.

Sharper is better. And that’s pretty much sharper is better, Period. A sharper tool cuts with less effort, is easier to control, and leaves a surface that needs less sanding. The less pressure you have to use to cut the less chatter you’ll get on the work and the less edge damaging heat you’ll generate. The question isn’t whether you need sharp tools but what is an unobtrusive way to get them. This article tells you how to make a sharpening system that has done that for me. It is inexpensive, quick to use, accurate, and capable of both extremely fine honing and moderately heavy grinding.

The system is based upon a cheap 8 inch Drill Press. The Drill Head is mounted upside down. The platform is mounted above it and supports the rest of the system. The drill press is used to drive a quick-change set of abrasive disks. Lubricant cooling is provided for all but touch up sharpening. Accuracy is insured by using the same jig for everything from the roughest grind to the finest hone. Three different jig supports are included. A multiple-angle platform sharpens roughing gouges (also works nicely on chisels and plane irons), skews, and scrapers. A V-Block Analog sharpens detail spindle and bowl gouges. A Straight Line Reference sharpens a variety of other tools.

Jigged grind and hone versus freehand

It is possible to sharpen turning tools freehand and do it well. Once you’ve learned to do it freehand you can sharpen with little interruption to your turning. It does, however, take a lot of practice, and most of us don’t even practice turning enough. If you are a beginning turner you are further handicapped by not having enough experience to know whether you’ve gotten it sharpened correctly or not.

Using a jig solves this problem as the jig enables you to sharpen correctly with much less practice. It can, however, trade one problem for another, because now you have the bother of finding the jig, resetting it correctly, attaching it to the tool, and adjusting the jig on the grinder. I’ve tried to avoid this problem using jigs that either don’t need adjustment or are contained in the tool handle where they don’t get lost.

Freehand Honing is also a skill that requires practice, if not as much practice as freehand sharpening. The Tormek system avoids this problem by using a relatively fine, re-gradable grinding wheel. The cost of this approach is that any heavy metal removal takes forever. I’ve avoided both of these problems by using the same jig for honing as grinding, and by allowing for practically instantaneous grit changes with a range from 36 to 3000.

I have had too many epiphanies (along the lines of “So THAT”S how it’s supposed to cut!”) after first sharpening a tool with a jig to ever go back to freehand sharpening and honing.

Flat versus Concave Bevel

There are differences between a flat and a concave bevel, but it’s unlikely that either your tool or the wood will notice the difference. There MUST be a clearance angle for the tool to cut, so the only part of the bevel that rubs is the first tiny fraction of an inch or so where the wood deforms (Look at the photographs on pages 34 and 35 of Mike Darlow’s Fundamentals of Woodturning). Rubbing the bevel is a metaphor. Just because it is a very useful metaphor that will help you keep your clearance angle small to maximize control and minimize surface defects doesn’t mean it is literally true.

You, however, may notice the difference between a flat and concave bevel. The main advantage of a concave bevel is that it is easier to hone by hand, as less metal needs to be removed. If you do not hone you will slightly increase the minimum clearance angle attainable. If you do hone the wood sees a flat bevel in the only part of the tool in contact. If you do manage to bring the heel of the bevel in contact with the turning wood you will scar the surface by compression. This will be worse for a concave bevel than a flat bevel.

No Fuss Jig Set-up

Jigs can be a great aid to better sharpening. Unfortunately the fuss of setting them up can also be a barrier to timely resharpening. First you have to find the jig, then reset it for the tool you want to sharpen (assuming you remember), adjust the jig on the tool and then adjust the jig to the grinder. You do not need to use the jigs in this article as other jigs such as the One-Way (what’s the name?) or Tormek jigs will work with a little modification for use with a flat grinding wheel. However I hope you will consider making my jigs for your tools. Most of my tools have the jig as part of the handle or stored in the handle. This makes them easy to find. They don’t need adjustment to the tool as they’re tool specific and only mount one way. This leaves only adjusting the jig to the grinder. I’ve found that the simpler it is to set up to sharpen the less likely I am to continue to work with a dulling tool.

No Fuss Abrasive Change

Being able to quickly change abrasives can be very handy at times. Profiling a new tool on a grinder as slow as the Tormek is torture to my mind. Restoring a nicked edge is close. Bench grinders use coarse stones, so you must hone by hand or use a coarse edge. With my sharpening system you can change abrasives literally in seconds. A much wider range of grits is available as you can use any 8 inch abrasive disk. I’ve found 60, 120, 220 and a honing disk to be most useful, but you can use 36 or 3000 and every thing in between. For routine edge touch-ups I use one disk with 220 grit on the outer half and a honing compound impregnated surface on the inner half. This requires NO time for abrasive change.

You also don’t have to worry about dishing the abrasive or dressing the abrasive when it gets clogged or dished. Just peel off the PSA abrasive disk and slap on a new one. I have no idea of the relative cost of a new grinding wheel versus the number of PSA disks that will do the equivalent amount of grinding, but even if the PSA disks are a little more, it’s worth it to not have to dress them.

No Edge Overheating

For each touch-ups with fine grit no cooling is needed. For heavier grinding I find lubricant cooling to be helpful. I don’t have to worry about overheating the tool, and I don’t have to breathe fine steel particles and silica dust. I started out using water, but adding a machinist’s coolant additive reduces the problem of rust and seems to clog up the abrasive less.

Suit refinement to the task

Because the abrasive can easily be changed you can suit the degree of edge refinement to the task. If you are cutting green wood with edge destroying dirt in the bark you may want to use a moderately coarse abrasive for quick edge restoration. On the other hand if you’re working a dry hard to sand wood you’ll want to take the time to work up to fine abrasive for the best surface off the tool. If for some reason your turning club has a cosmetic bevel contest, with a little extra time on a honing disk you can have a mirror bevel you can shave in or with.

Un-copyright

The sharpening system and the plans are not copyrighted. You can copy and distribute the plans as you wish. If you come up with improvements to the system I hope you will feel morally bound to freely share them, but as I do not wish to copyright the plans I cannot require it.

Safety

There are some obvious safety considerations. I use an electric tool in a fashion it was not designed for. Adding liquid lubricant to a system without special electrics adds some shock hazard. The on-off switch ends up upside down. There is some potential for the abrasive disk holder to be launched Frisbee fashion. I do not feel unsafe using the tool, but certainly I would not suggest using the tool if your spouse is an OSHA inspector. You, however, may have different work habits and different concepts of risk, and will have to make your own determination and take responsibility for it.

It is possible to modify the plans to reduce the appearance of risk. You can relocate the on-off switch and shroud the motor to shield it from lubricant, or alternately forgo using lubricant. You could forgo some speed of abrasive change in exchange for a more secure disk attachment. If you do not wish to use the quick-change disks, simply buy extra extra Aluminum Grinding Disks from WoodCraft. Do not add setscrews on the rim. Adjust the fit of the ½” drive shafts so that all are of exactly equal length. Put you abrasive disks directly on the commercial grinding disks and change the whole unit as needed. Making an extension for the chuck key will make change-over go more smoothly.

Making the System

Modifying the Drill Press

The first step is to buy an 8 inch drill press. I bought a Delta, but I imagine they’re all pretty much the same, or can at least be made to work. There are two tasks in this section: modifying the drill press so that the head can be mounted upside down, and removing part of the support column to provide clearance for the coolant collection system. I’ll describe what I’ve done. Feel free to add steps for a neater end result if that matters to you.

Allowing Head inversion

The modified Head

The first step is to remove the top belt cover. A brief attack on the hinges with a hammer and cold chisel or diagonal cutters will suffice. I feel that when the head is inverted and mounted close to the base that this adequately isolates your fingers from the belt drive. This also makes changing speed easier, but I very rarely do that. If you wish, you could cut a wide slot in the cover to allow it be opened despite the support column.

The second step is to cut a hole in the bottom belt cover to allow the support column to go through it. I attacked it with a hammer and cold chisel until sufficient clearance was had. If you want neat you can perhaps remove the entire assembly.

The third step is to remove the drive pin that serves as a stop for the support column. It is inside the head. Just twist and pull it out with a pair of pliers.

Support Column Modification

The modified Support Column.

Temporarily assemble the drill press. Attach the support to the base if it isn’t already done, and slide the head upside down on the column until the pulleys are about a half-inch from the base. Mount the drill chuck if it isn’t already done. Slide the table (right side up!) down the column until the table is about a half-inch above the drill chuck. Take a marker and mark the upper level of the table on the support column. Remove the table and head from the support column and the column from the base.

Make another mark two inches above the first mark. Use an angle grinder and cut off disk (or a hacksaw if you feel under exercised) to remove the front third of the column between the two marks. Clean up the worst of the burrs so that you can reassemble the unit. Remount the support column on the base. Install the belt so that the lowest speed is obtained. Slide the head assembly upside down on the column until the belts clear as before and lock it securely in place.

Making the Grinding Drive and Disks

Making the Grinding Drive

It is easiest to start with an aluminum plate with a ½” ID designed to mount PSI disks (see Sources of Supply). Flip the disk over so that the ribs and arbor mount are up. Us a pair of dividers or compass to mark out three equally spaced holes 1/4'" inside the rim. Center punch the holes and drill with a #7 drill. Then tap for 1/4x20 threads. Insert a 1/2" long 1/4x20 set screw in each hole and adjust so that it protrudes just less than 1/8" on the flat side of the plate. Screw on a ¼” nut from the ribbed side to lock the set screw in place.

Cut a 3” piece of ½” drill rod and debur both ends. File a flat to mate with the locking screw on the arbor. Make the flat about 1” long to allow you to adjust the projection of the rod.

The bottom of the grinding drive. / The top of the grinding drive mounted in the splash shield.

Making the Disks

Make the disks to mount abrasive out of 1/8” thick aluminum plate (see Sources of Supply). The size plate you buy depends on the number of disks you want to make, which in turn depends on the number of grits you want to be able to easily use.

Lay out the disks. I used a CAD program to draw an 8” circle with three equally spaced holes and printed it out on 8.5x11 self stick labels. You could draw the circle and holes once, then copy them with a copier and use spray adhesive to attach to the aluminum plate. You could also use a thin line marker and trace the grinding drive disk.

Two finished disks. Abrasive has been attached to the one underneath.

Cut out the disks using a metal cutting blade on a hand held scroll saw. Center punch and drill the three holes with a 5/16” drill. Counter sink gently from both sides. It is best to approach this task slowly and clamp the disk down each time before drilling. Check and make sure that the disk will fit on the grinding drive disk in all six possible orientations (rotate 120 degrees three times, flip over, rotate 120 degrees three times). If your metal working skills are under precise, like mine, you will likewise have to fall back upon the methods our Revolutionary era Forefathers used: Come close and file to fit. Use a small round file to adjust the holes if necessary.

To attach the PSA abrasive disks, simply remove the backing, center on the aluminum disk, and press. If you want to use both sides of the disk, use a trash pair of scissors to remove notches so the pins can get into the holes in the disks.