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Very Sharp as 9 page pdf

This article was published in the Spring 2006 edition of Woodturning Design. 

Very Sharp, Very Easy, Pretty Quick

Introduction

Story

This article describes a home made sharpening system.  Because it uses progressive grits of abrasive ending with honing compound it gives Very Sharp edges.  Because it is jig-based but uses a minimum of non-fussy jigs, it is Very Easy to use.  Because progressing to finer grits does not require any resetting of the jig it is Pretty Quick.

I’ve tried many different sharpening systems; some bought, more home-made.  Each time, in the beginning, like Cindy, a thrice divorced woman I know (it’s her real name because she’s not a real person); I thought this was the one.  But after a while, some bad habits or difficulties would surface, and I’d find myself turning with a less than sharp tool because I didn’t want to go the trouble of setting it up to sharpen.

What I got this time isn’t quite what I set out to design.  I wanted to build a wet system that would equal or exceed the edge from a Tormek, but that would be able to share the jigs and geometry of a dry bench grinder when heavy shaping was necessary.  I knew from using my various wet/flat disk systems that using successively finer sandpaper would let me get to a really sharp edge quicker than a Tormek, so I first built a sandpaper covered cylinder running in a coolant bath.  This did work.  But the coolant tended to loosen whatever adhesive I used to attach the sandpaper…and it didn’t take much of a loose flap to make quite a mess.

It finally dawned on me that most of my tools are heat resistant High Speed Steel, and that if I kept the speed down there wouldn’t be much heat build-up anyway.  So I got rid of the coolant bath and extreme speed slowing jack-shaft and ended up with what I’ll describe in this article.

The system uses an 8” mdf cylinder that is covered with three grades of sandpaper and a final honing area of honing compound directly on the mdf.  It turns about 500 rpm, away from you on top so the tool doesn’t dig in and cut the abrasive.  To enable use of the same geometry and jigs of my bench grinder, it uses a sliding V-block.  But to let me quickly change positions to the next finer grit, it’s a compound sliding V-block that moves sideways as well as back and forth.

Advantages

Since the system starts with relatively coarse abrasive (I use 80 or 100 grit, but it’s your choice) initial setting of the sharpening jig isn’t overly fussy.  Since the final grit is very fine (I use 320 and honing compound, but again it’s your choice) the tool will be really sharp.  Since switching grits only entails sliding the V-block sideways with no resetting required, it’s pretty quick.  I timed how long it took to sharpen a 1” skew.  Starting from an unset V-Block (and with the system rather awkwardly placed on the floor) it took 1 minute and 2 seconds.  Resharpening with the V-Block already set took 28 seconds.

It’s not possible to dish sandpaper, so you don’t have to breathe clouds of Aluminum Oxide while you dress the abrasive.

It uses a simple V-Block and the same jigs you probably already have.  And when heavy grinding or shaping is required you can go back to your bench grinder without changing the geometry of your tool.

Since it uses jigs you can get very sharp tools after climbing a minimal learning curve.

Caveats

Life always requires compromise.  Maybe Cindy needs to learn that?  Anyway:

Since the abrasive turns away from the edge, no burr is built up for a scraping cut.  The combination of a bench grinder and the Veritas scraper burnisher works better.

Since the abrasive turns away from the edge, moderately heavy sharpening may produce a feathered edge that must be removed before moving to the next grit, but you can just drag the edge sideways through a block of wood.

The system isn’t really suitable for freehand sharpening.  A jig based system will always take a little longer than freehand sharpening, but it’s a lot easier to learn.

Building

Base

To make the base I cut two rectangles of ¾” plywood 14” x 15”.  I glued them together using polyurethane glue (if you substitute regular wood glue allow two days for curing).  Since I didn’t have any clamps that would reach into the center of the base, I clamped it using 8P duplex nails.  I just cut a handful of the nails shorter so they wouldn’t go all the way through.  After letting the polyurethane cure overnight, the duplex nails pulled out easily.  It is essential that the 15” sides be cut perpendicular to the bottom of the base and parallel with each other, else the compound V-Block will bind, so I trimmed the edges on my table saw.  The slight loss of width and length isn’t important.

Next I cut two Bearing Supports, 4” x 8”, out of common construction lumber.  To mount the Bearing Supports I placed them on the Base along the 15” sides, flush with the front and traced them.  I then drilled clearance holes for three screws on each side.  Next I put some glue on each Bearing Support in turn, held them in place with clamps, and mounted them with three 3” wood screws.

Cylinder

To make the cylinder I started by cutting a 15” long piece of 5/8” drill rod.  I used a grinder to bevel the ends a bit.  Then I mounted the drill rod in a four-jaw chuck in my lathe, checked to make sure it ran true at a slow speed and used a V-shaped cutter to make a dimple for my tailstock.  You could also just use a small drill, either by hand or on the lathe, just make sure it’s well centered.  Once the dimple is made, I engaged the tail stock and make sure the drill rod ran true.  Then I removed the drill rod from the lathe.  Next I checked to make sure the drill rod would fit into my pillow block bearings.  One end didn’t fit, so I returned the drill rod to the lathe and used a file to trim it just a bit (if you must know, I actually made things a bit harder on myself by not doing this until the cylinder was completed).

Next I prepared the mdf for mounting on the drill rod.  I cut out two 7-¼” squares, and eleven 8 ¼” squares.  I used a drill press to drill a 5/8” hole in the middle of each square.  I used a chisel to clean up the exit holes, Then I made a 7-¼” and an 8-¼” circle template out of thin cardboard and used it to trace the circle on each mdf square.  Last I roughed out each square to round on my bandsaw.  The object is to get circles with a hole right in the middle.  I though it was easier to jig up a square for drilling, but I could just as easily have used a circle template to mark the center as well as the outline, cut them out on the bandsaw and then drilled them.  Which ever way you do it, use a hold down and a fresh substrate to back up the mdf when drilling to minimize tear out.

I laminated the mdf disks together right on the shaft.  First I clamped the shaft vertically in a vise so that 2 ¼” of it was below the top of the shaft.  I slid one of the 7 ¼” disks down the shaft to the vise.  I used a credit card sized piece of cardboard to spread polyurethane glue evenly on the second 7-¼” disk then slid it down the shaft glue side down.  I repeated this with each of the 8-¼” disks.  Then I removed the shaft from the vise and used four clamps to clamp the disks together. 

After the glue had cured over night I mounted the laminated cylinder on my lathe, using my four-jaw chuck and tail stock.  I used my One-Way 1018, which didn’t have clearance for the tool rest banjo under the cylinder, so I had to turn half at a time.  It’s not wise to inhale mdf, so I turned on my dust collector and wore a mask the whole time I was working on turning the cylinder.  I started by using my roughing gouge to reduce the 7-¼” disks to round, about 7” diameter.  Then I made a small cardboard template to match the groove for the drive belt by just trimming until it fit the 2” pulley destined for the motor.  I returned to the lathe and used a parting tool to cut a groove for the belt, using the template as a guide.  When I thought it fit I double checked using the belt itself.  Then I started roughing the 8-¼” disks to round, aiming for an 8” diameter.  After I had the right side of it done I had to remove the cylinder from the lathe, move the banjo under the chuck, and remount the cylinder.   Then I finished turning the cylinder. 

While the cylinder was still mounted on the lathe I masked off two inches on one end for honing compound.  Then I applied a coat of sanding disk cement by pouring the cement on and using a credit card sized piece of cardboard to spread the glue whilst turning the cylinder by hand.  Mdf absorbs a lot, so you may need to do two coats.

While my fingers were sticky I prepped some abrasive cloth belts.  The grits you choose depend on your sharpening needs, but the series 60, 120, and 220; or 80, 180, and 320 are good places to start.  The blue zirconium oxide abrasives are very durable for grinding metal, but aren’t commonly available in finer grits.  Aluminum oxide is a good choice.  I happened to have some Klingspor Gold cloth on hand so that’s what I used.  The belts tend to curl up after being coated with glue, so I had some weights on hand.  I spread newspaper to contain the mess, poured out some sanding disk cement, and spread it with a piece of cardboard.  Again, two coats may be needed.  Spray adhesive may also work, but I haven’t tried it as a primary adhesive, just used it to quickly tack back down an errant flap.

Once I the glue cured I put the abrasive belts on the Cylinder.   I had cut them a bit long, so once they were in place I trimmed off the excess either by tearing or using a trash pair of scissors.

Compound Sliding V-Block Rail Guides

To make the Compound V-Block I started by cutting rails and a cross piece, using construction lumber for all three pieces.  The length of the rails is optional.  As I have one long handled bowl gouge ground straight across, I needed fairly long rails.  Mine were 1-½” x 2” x 34”.  I cut the cross piece 1-1/2” x 4” x 19”.  I only needed to be able to measure the actual rails at this point; I assembled the Compound V-Block later. 

Next I cut pieces for the Rail Guides out of ordinary ¾” pine.  I wanted the inner space of the guides to be about 1/8” larger than the rails to prevent binding.  The actual dimensions you need will need depends upon the size of your Rails and the thickness of the stock you make the Rail Guides from.  The width of my Rails plus 1/8” was 1-5/8”.  The height of my Rails, plus two thicknesses of pine plus 1/8” was 3-5/8”.  Using these measurements I cut 4 pieces 1-5/8” x 8”, and 4 pieces 3-5/8” x 8 from the ¾” pine.

I used some homemade ½” threaded wood to clamp the rails in place (they look dirty in the pictures because they are recycled from a previous project).  Wood threads are great for this use, as they’re strong enough, but don’t dent the rails.  If you don’t have a wood threading set you can use a coarsely threaded bolt and protect the rail with a flexible piece of sheet metal.  Or you could buy threaded nylon.  Whichever method you choose, choose it now so you can drill the proper size tap hole.

I drilled tap holes in two of the 3-5/8” x 8” pieces, centered widthwise, 1-1/2” from each end.  Next I drilled four clearance holes for the assembly screws 3/8” from each long edge 1-1/2” from each end in both of these pieces.  I used my wood threading tap to one of the tap holes in each piece.  Then I drilled two clearance holes at the same location as the tap holes and four clearance holes in the other two 3-5/8” x 8” pieces.  I changed the distance from the ends to 1” so that the screws wouldn’t interfere with each other. 

Next I assembled the Rail Guides using some 1-1/2” #8 screws.  I used clamps to temporarily hold the pieces in alignment while I drove in the screws.  To mount the Rail Guides I turned the Base on its side, and aligned a Guide with the bottom and front edges of the Base.  I dropped a 1-1/2” #8 screw into the two clearance holes and drove it in using the tap holes for screwdriver access.  I flipped the base over and mounted the second Rail Guide the same way.

Mounting Cylinder and Motor Mount

To mount the Cylinder I slipped the pillow block bearings on to the shaft.  I adjusted the placement of the bearings so that the bearings would be in the middle of their respective Bearing Support, and that the Cylinder would be in the middle of the Base between the Bearing Supports.  I slide the bearings back on the Bearing Supports so that the front edge of the Cylinder aligned with the front of the Base.  Then I marked the location of mounting holes.  I removed the Cylinder from the Base, and drilled pilot holes for 5/16” x 2” lag screws.  I replaced the Cylinder and mounted it on the Base using the lag screws and washers.  I tightened up the set screws that hold the shaft in place on the bearings and gave each bearing a shot of grease just in case.

I prepped the motor by temporarily wiring it to the cord without the switch and plugged it in to check that the rotation direction.  The cylinder must turn away from the front on top.  If the rotation is wrong, switch the wiring according to the wiring diagram supplied on the motor.  If you can’t or don’t want to rewire, you can turn the motor and cylinder the other way, and construct a mirror image of my Belt Guard.  I readied the cord for wiring to the switch by removing the outer insulation from about 15” of cord.  I cut the now exposed white and black wires about 7” from the end, striped the cut ends, and attached spade connectors.

I cut a 10” square of ¾” plywood for the motor mount.  I cut two 4” long slots for mounting screws starting at the front 2” from the sides.  I slipped a 2” pulley on the shaft of the motor, put the Motor Mount towards the back of the Base and between the Bearing Supports, and set the motor with its back edge at the back on the Motor Mount.  I played with the position until I could align the pulley with the slot for the belt on the Cylinder.  I marked the mounting holes for the motor, removed the Motor and Motor Mount from the Base, and mounted the Motor.  This time I used ¼” x 1-1/2” carriage bolts, but for the prototype I just used wood screws.  Choose and drill pilot holes accordingly.

Once the Motor was mounted on the Motor Mount I replaced it on the Base and secured it with a wood screw and washer through each slot.  I temporarily tightened it in place, and measured the belt material around the pulleys.  I removed excess belt material to get the correct length and assembled it.  Make sure it’s around the cylinder when you do this.  I loosened the Motor Mount screws, put the belt in place on both pulleys and applied moderate tension.  Then I fastened the Motor Mount in place.

Assembly of Compound V-Block

I started the assembly of the Compound V-Block by using three 2-1/2” #10 wood screws to fasten the Crosspiece at a right angle to one of the Rails.  Then I inserted both Rails in the Rail Guides, and temporarily fastened the Crosspiece to the other rail with one screw.  I confirmed that the assembly would slide in and out without binding, and then inserted two more screws.

I cut two 1-1/2” x 2” x 4” Rod Supports out of construction lumber.  I drilled a 5/8” hole 1” from the 2” edge centered widthwise.  For convenience I cut a notch in one of the Rod Supports to measure the set-back for my Vari-Grind gouge grinding jig. 

I cut two 1-1/2” x 3” x 5-1/2” pieces for the Sliding V-Block out of construction lumber.  I glued the pieces together to make a 3” x 3” x 5-1/2” block.  After the glue dried I drilled a 41/64” hole 7/8” from the bottom and 1” from the 5-1/2” edge.  If you don’t have a 41/64” drill, drill 5/8” and enlarge the hole a bit with a round file.  Then I cut a 1-1/2” x 1-1/2” block from the corner opposite the hole.  I cut out a V-shaped notch from the remaining wood, then glued the 1-1/2” block back in place.

To attach the Sliding V-Block to the Crosspiece I inserted the remaining 5/8” rod into one of the Rod Supports.  Then I slid the Sliding V-Block onto the rod and inserted the rod into the other Rod Support.  I used a #10 3” wood screw to temporarily fasten the notched Rod Support to once side of the Crosspiece.   Using my roughing gouge, I adjusted the placement of the other Rod Support until the gouge bevel rubbed the cylinder at both ends.  Then I permanently fastened the Rod Supports with more wood screws.  I used a 2-1/2” instead of a 3” screw through the notch on one Rod Support.

Belt Guard

To make the Belt Guard I cut a piece of ¾” plywood 7-1/2” x 14” for the Belt Guard Side.  I held it up against the side of the Base Support, with the front edges flush, and marked where the 5/8” shaft hit it.  I drilled a 1” hole at this point to provide clearance for the shaft.  I also drilled clearance holes on the bottom to mount the Belt Guard Side, and clearance holes on the top to mount the Belt Guard Top.

Next I cut a piece of ¾” pine 7” x 14” for the Belt Guard Top.  I temporarily held the Belt Guard pieces in place and marked how far over the Belt Guard Top should go to cover the belt but not the abrasive on the cylinder.  I cut this area out about 6” back.  I again held the pieces temporarily in place and marked where I wanted to put the switch.  I wanted it close to the junction box on the motor (mostly because I was recycling the motor and short wiring from an older project), but not where it would interfere with the Cylinder.  I traced the bottom of the switch on the Belt Guard Top, and cut this area out with a scroll saw.

I used #8 1-1/2” wood screws to fasten the Belt Guard Top to the Belt Guard Side.  Then I used the same size screws to fasten the assembled Belt Guard to the Base.  I pulled the wires for the motor up through the hole for the switch, and clipped the spade connectors on to the switch.  Be sure to pay attention to the input and output sides of the switch.  Then I pushed the switch into the recess. 

Finally I turned the system on and applied some honing compound to the Cylinder.  As a test I sharpened my roughing gouge, marking the bevel with a permanent marker in between grits so I could be sure the finer grits were grinding to the edge.  It’s okay if the finer grit misses the back edge of the bevel.  You can loosen the pillow block mounting bolts to make corrections.

Using

To sharpen a tool you simply start by sliding the V-Block over on its shaft so that it’s in front of the coarsest grit abrasive, then slide the Compound V-Block assembly in or out until the bevel on your tool rubs while pushing back on the V-Block somewhat.  Then turn the system on and touch the tool to the abrasive.  Pull it back and make sure that it’s grinding the whole bevel from front to back.  Putting Permanent Marker on the bevel may help here when you’re learning how to use the system.  Make any need adjustments, then grind the tool on the coarsest abrasive.   Remember to push back into the V-Block all the time.  If you do any heavy grinding you may get a feather edge.  If you do, remove it by dragging the edge sideways through scrap wood (I use the back edge of the Compound V-Block Crosspiece).  Then slide the V-Block over on the shaft and grind using the medium abrasive, slide over again and grind using the fine abrasive, then finally slide over and hone with the honing compound.

Some specifics for popular tools:

Roughing Gouge and Bowl Gouge ground straight across:  Slide the Compound V-Block out until the bevel rubs, the rotate the tool to grind the whole edge.

Parting Tool:  Slide the Compound V-Block to where the bevel rubs, then grind and flip over to do the other side.  Be sure to grind so that the edge stays in the center of the tool and is straight across.

Skew:  Slide the Compound V-Block so that the bevel rubs, then grind and flip over to do the other side.  Centering the V-Block yields a skew with an angle that changes slightly from toe to heel.  I don’t find this to be a problem.  You could slide the V-Block between sides to keep the angle constant like the One-Way skew jig, but be careful to keep the position repeatable.  Perhaps a better solution would be a sliding block with two V pockets.

Fingernail & Side Ground Gouges:  Mount the gouge in the jig of your choice.  Using a jig to set the set-back makes things a lot easier and more repeatable.  Adjust the position of the Compound V-Block, the rotate the gouge and jig to grind the whole edge.  You may find that the jig fouls on the Cylinder when trying to grind an extreme side ground gouge with a bulky jig such as One-Ways Vari-grind.  Increasing the set-back will probably solve this.

Materials

Contact information:

MSC:  www.mscdirect.com 1-800-645-7270

Grizzly:  www.grizzly.com, 1-800-523-4777

Me

David Reed Smith, a member of the Baltimore Area Turners, lives in Hampstead , Maryland .  A pre-edited version of this article, with more pictures and perhaps alternate solutions, will be available at www.DavidReedSmith.com.  He welcomes questions, comments and suggestions (you wouldn’t believe how little feedback there is) via email at David@DavidReedSmith.com.