A few spoons and a dissection...

I was trying to close the upper portion of a window a couple of days ago and couldn't quite reach it.  I grabbed my workshop spoon, paused for a moment, and then pushed up on the window with the back of the handle.  I gave it a good shove and half of the bowl split off.

I was never satisfied with that spoon, which is why it never made it out of the workshop.  But I immediately saw new value in it.   I planed the handle down to the center line and now I have a perfect longitudinal section straight down the middle of the spoon which illustrates a couple of basic points of spoon design.

Notice the shape of the bowl.  The depth is in the back.

If you look closely at the pictures above you can see that the depth of the spoon's bowl is toward the back.  The front portion of the bowl is like a ramp leading down into that depth.  Notice how flat the front of the bowl is.  This shape, with the depth in the back and the front relatively flat, holds a good scoop of food while still allowing your upper lip to slide all the way along the bottom of the bowl and sweep that food into your mouth.  When the shape is right, eating from a spoon is a satisfying experience.  When the shape isn't right, the edges of the spoon dig into your lips and there is a morsel of food that has escaped your lip left in the bottom of the bowl after each bite.

Outside of the dissected spoon.

The other important detail to notice from this spoon dissection is how the thickest portion of the spoon relates to the depth of the bowl.  From the side I like a spoon to be an arrangement of sweeping curves.  This spoon was carved from a piece of straight lilac, so the curves are gentle and when you are not looking at them the spoon has the appearance of being flat.  My experience is that when a spoon is truly flat, it looks dead.  A few gentle curves along the length as the handle swells to the depth of the bowl gives the spoon a more lively look.  The neck of the spoon is the same thickness as the deepest part of the bowl, from the neck the thickness sweeps away into the thin part of the handle where the spoon is held.

Apple eating spoon of similar design.

Since I never really cared for that spoon I didn't want to post pictures of it all alone for the spoon nuts of the world to see, so I went through our spoon mug and pulled out a couple of old favorites.  As you look at the pictures think about how the different parts of the spoon (the bowl, the neck, the handle, and the finial) relate to each other.  Or maybe you feel that they don't relate to each other.  Looking at the shapes of the spoons like that helps to build your idea of a pleasing spoon.

These are a few that I enjoy.

Sweet birch serving spoon.

Rhododendron eating spoon. 

Steambent paper birch eating spoon.

Simple Band Saw Fence

My band saw is the machine workhorse of my workshop and I find a band saw fence useful for ripping parts close to dimension, but also for precisely ripping tenon cheeks and cutting other joinery.  I built this wooden fence for my band saw almost immediately after I bought it.  The slot in the table for removing and replacing the blades is on the front of my saw which makes it incompatible with most aftermarket band saw fences.  After using this set up for the past four years, I wouldn't want anything else.  It is accurate, easy to adjust, and the price is right.

Wooden band saw fence.

If you are looking at these pictures and thinking, "How do you adjust this fence for blade drift?" then your life is about to get simpler.  Blade drift is caused by the crown of the bandsaw tire.  When the blade is centered on the crown of the tire your band saw won't drift (assuming your saw is well tuned and you have a blade that has a good weld and large teeth and gullets for removing saw dust efficiently).  If the blade is forward or behind the crown of the tire, then the blade will drift at a consistent angle.  To correct, adjust the tracking of the blade to the center of the wheel.  

My fence is square to the front edge of my band saw table.  I adjust the blade tracking to the center of the wheel each time I install a new blade.  I have never had a problem with blade drift.  Michael Fortune wrote a great article a few years ago for Fine Woodworking that covered this and some other band saw set up and tuning information.  I think it is the most comprehensive source for basic band saw set up and blade selection.  Here is the link.

The fence is made from a scrap of 8/4 red oak that is 3 1/2" wide.  The rail that references against the front edge of the table is a piece of  3/4" plywood that is 3 1/2" wide.  The fence and the rail are joined square to each other with a liberal quantity of screws to keep the fence from racking in use.

Notice the leather shim between the fence and the rail.

One detail not to miss is the shim between the fence and the rail.  I used leather because I had a scrap laying around, but a piece of a cereal box or some other similar flat cardboard would work as well.  The bottom of the fence lays flat on the table and the shim keeps the rail down below the surface of the table so that it does not interfere with the wood being sawn.

Clamped in place.

The face of the fence is planed square to the bottom.  A 24" Irwin quick grip clamp holds the fence in place on the saw.  The fence needs to be a little bit shorter than the length of the table so that the jaw of the clamp on the far side of the table is pressing on the table and pulling the rail tight against the front edge.

Fence does not extend past the band saw table.

With very light clamp pressure you can slide the fence back and forth to set the distance from the blade.  I use a steel ruler butted against the fence and take a reading from a tooth that is set toward the fence.

Setting the fence.

Apply full clamping pressure and you are ready to saw accurately.

Micro-adjust for Sorby Sizing Tool

A sizing tool used with a beading and parting tool is a quick way to turn tenon after tenon on the lathe to within a couple thousandths of an inch in diameter.  Precise sizing of the mortise and tenon produces very strong joints.  Combine that with optimal grain orientation in the joint, assembly of the pieces with the tenon at a lower moisture content than the mortise, and a little hide glue; and you end up with chair joints that can withstand a couple of hundred years of abuse.

But getting the sizing tool set up to cut exactly the diameter that you want has been a frustrating process.  Accurately sized set up blocks followed by taking measurements with a micrometer get you in the ball park, but getting the final adjustment from there has been a trial and error process: loosen the thumbscrews, attempt to move the sizing tool two thousandths of an inch closer to the cutting edge, and try again until you get the exact size that you want.  Sometimes the set up goes quickly and sometimes you end up chasing your tail for a little while.

Last week while I was doing something else I had a head slap moment and realized how to make a simple adjuster that would introduce more control into the trial and error.

The adjuster has a square mortise to slide over the beading and parting tool, a set screw to secure it on the shaft, and a thumbscrew to press against the back of the sizing tool and aid in adjustment.  In the photo above, note the counterbore that gives the thumbscrew more clearance.  The adjuster has to be compact so that it fits in the space between the ferule and the back of the sizing tool.

I cut a notch out of the upper portion of the adjuster to give the thumbscrew on the sizing tool clearance to tighten.  The thumbscrews of the sizing tool must be loosened for adjustment.

I tapped the holes for the screw threads.

It works brilliantly.  It is still necessary to do test cuts to set up the tool, but the process is a little bit less like flying blind.

Adze Grinding and Sharpening.

I recently finished up a batch of the adzes that I make and grinding and sharpening all of the blades provided the opportunity to show how I go about creating and maintaining their edge geometry.  My process is specific to my adze, but the techniques could definitely be adapted by a clever person to sharpen other adzes.  If the grinding set up that I use seems overly complex, skip to the bottom for other options.

My adze blades have both interior and exterior bevels.  The exterior bevel is hollow ground and if the hollow has been mostly removed by honing I begin by regrinding the bevel.  My grinding set up is half Rube Goldberg, so  I'll start with a picture of the entire rig and then walk back through the components and hope that it all makes sense in the end.

Adze grinding set up using the Woverine V- arm attachment.

The heart of my setup is the V-arm attachment that comes as part of the Wolverine grinding jig.  I use the V-arm in conjunction with an angled wooden grinding fixture to hold the blade at the desired angle.  It is just like regrinding a turning gouge, rotate the assembly in the V-notch and grind away, with a light touch.  I recently switched to using the 3X 46 grit blue wheels from Tool for Working Wood for on my grinder, which basically takes overheating the edge out of the equation.  If you are in the market for new grinding wheels, or have had trouble overheating other tools, I can't recommend them more highly.

Grinding jig and adze blade.

My adze blades are easily removable from the head and have a flat rear section that can be clamped to the angled ramp of the grinding jig with a small C-clamp.  The overall length of the jig, without the blade, is 12 1/2".

Blade clamped in place.

I visually center the blade on the jig and align the edges of the blade parallel to the edges of the jig.

Blade aligned and clamped.

Well, I get it close any way.

Blade positioned in line with the grinding jig.

The outside of the blade at the edge should be in line with the bottom side of the grinding jig.  The basic theory here is that the outside of the blade at the edge should be in a direct line with the wooden grinding jig, and the shape of the wooden grinding jig where it rests in the V-arm should be approximately the same shape in cross section as the sweep of the adze blade at the edge.  

I had to read that sentence a couple of times to see if it made any sense.  Hopefully the pictures help.

Curvature of grinding jig roughly matches sweep of adze blade.

You can see from the last picture that this doesn't have to be an exact match, but as the difference in curvatures increases, grinding becomes less consistent and more difficult to control.  The end of my grinding jig is 2 1/16" in diameter.  It was the biggest piece of scrap I had on hand.  When the edge is traveling in the same path and turning at the same rate as the part of the jig rotating in the V-arm you get a nice consistent grind.  When the back of the grinding jig is significantly smaller than the sweep of the adze blade, the angle of the grind decreases dramatically as the blade rotates toward the corners.

The ramp that the blade is clamped to is angled at 22 degrees.  There is slight variation of the curvature of the blades, this angle has worked well throughout the range of variation.

Testing the grind angle.

With the blade properly positioned I take the assembly to the grinder and lock the V-arm in position when the bevel appears to be laying flat on the wheel.  Then, with the grinder off, I rub the blade back and forth to confirm that the assembly is properly aligned.  I remove the assembly and check the bevel to see that the scratches from the wheel are centered on the bevel.

Scratches from the grinder are centered on the bevel.

If the scratches are slightly forward or back from the center, I adjust the position of the V-arm to achieve the desired alignment.  

The final adjustment before grinding is to position the assembly at the grinder and swing the blade to either corner and rub it side to side to confirm that the wheel is still striking the center of the bevel at the two most extreme points.  If the alignment is off, usually the scratches will run up to the edge on one side and to the back of the bevel on the other.  If this is the case, I skew the blade on the ramp to compensate.

Skewed blade to adjust for misalignment at the blade corners.

The picture shows a blade that is skewed more than I have ever found necessary, to clearly illustrate the idea.  When the blade is skewed the corner that moves forward, will climb slightly up the face of the grinding wheel, which will move the scratches away from the edge and towards the center of the bevel.  The corner that moves back will slide down the face of the grinding wheel, which will move the scratches from the back of the bevel, toward the center.

I adjust, confirm that the adjustment has aligned the blade properly and then grind.  The grinding is quick and the hollow makes it easy to maintain the performance of the tool.  When regrinding I never grind all the way to the edge.  I always try leave a small polished flat.  I treat the bevel on the outside similar to the way I treat the back of a chisel.  I usually raise a burr by sharpening with coarse abrasives from the inside and only use fine abrasives on the outside to polish and roll the burr back to the inside for removal.  Using this technique extends the amount of time between grinding sessions.

Inside of the blade.

The inside of the blade is microbeveled.  The total included angle of the edge should be around 35 degrees to withstand the rough use that the adze is put to.  It is important that the inside bevel be micro to keep the resistance of the blade as it cuts through the wood low.  A big fat bevel on the inside the blade makes the adze feel sluggish in use.  Keeping the inside bevel small allows the tool to slide right through the wood with a minimum of effort, while the microbevel gives the edge durability.  I learned this from the Yanesha bowl carvers I worked with in Peru.  They spend day after day swinging their adzes and need their tools to cut aggressively and have the edges last as long as possible.

I use a dremel to remove material behind the micro bevel.  In the absence of a handheld rotary tool, coarse sandpaper wrapped around a dowel works well.  This step isn't necessary every time you sharpen the blade, but keeping the microbevel small keeps the tool functioning at a high level.

Diamond paddles and a drill bit wrapped in P600 wet/dry sandpaper.

When the grinding is done on the outside and the material behind the micro bevel has been removed with a rotary tool or coarse abrasives, honing commences.  I use diamond paddles for honing the outside of the tool and a drill bit wrapped in P320 or P600 wet/dry sandpaper for honing the inside.  A dowel wrapped in sandpaper works just as well as the drill bit.

Raising a burr from the inside.

I begin resharpening by forming a burr from the inside with P320 wet/dry sandpaper.  To check the angle I set an angle gauge to 35 degrees and rest one arm of it flat on the exterior bevel.  I position the other arm close to but not touching the interior bevel and check to see that it is parallel to the gauge.  If it is not I focus my attention on the front or back of the bevel to adjust the angle.  Some convexity here is not a problem.  If the angle gets too obtuse, you'll know because it will feel like you are beating the wood apart when you start to use the tool.  It should feel like the blade slices through the wood with little effort.

Honing the bevel.  Be aware of your fingers.

Next, I hone the exterior bevel with a fine diamond paddle.  I press the paddle flat onto the bevel and slide it back and forth.  While doing this it is important to consider where a slight slip of your hand could put your fingers, with the burr raised contact with the edge can leave a fingertip on the floor in a hurry.  I feel confident using the position demonstrated in the photo above, but note the potential danger.  I move the paddle with slow, deliberate motions.

With the outside honed, I switch to P600 paper on the inside to polish the scratches and then alternate between honing the inside and outside to remove as much of the burr as I can before stropping.

I strop the outside using the same technique I use on carving gouges.  I place my fingers on the edges of the blade and rotate the blade side to side as I pull the tool along the strop.

Strops have a bad reputation for rounding over the tool edges.  To minimize the rounding at the edge, I place the bevel flat on the strop and then emphasize the pressure on the back of the bevel.  The leather deforms enough to polish the edge, but with pressure emphasized on the back of the bevel, rounding at the edge is reduced.

The slipstrop I use to polish the inside.

I use the slipstrop I made a few months ago to strop the inside.  It it takes five minutes to make and works brilliantly.

Stropping the inside.

I alternate stropping the inside and outside until all traces of the burr are gone and the blade takes clean shavings from pine endgrain.

I sharpen the blades this way for a couple of reasons.  My grinding jig allows me to controllably grind the same amount of bevel on the outside of each blade and the hollow that it leaves is easy to hone.  I want the tools that I send out to customers to be at peak performance, so that when that person starts using the tool, the way the tool feels becomes the standard of performance for them.  If that person resharpens the tool and some aspect of the performance has changed, they will know that the tool isn't functioning at its full potential.  If they cannot figure out the problem they are welcome to contact me to help them address it.  The key is knowing how the tool should perform.  The hollow grind allows me to repeat the process over and over, and know that I am sending out tools that are working at the highest standards.

That said, if you don't have a grinder, or feel intimidated by the grinding set up and potential risk of overheating the blade, you can get great results from freehand sharpening the exterior bevel on sharpening stones, just as you would a gouge.  I sharpen gouges by rocking them from one corner of the edge to the other as I move the tool lengthwise along the stone.  It is easy to maintain a flat bevel with this technique. blade detaches from the body and it is easy to manage on stones.  Try to mimic the existing bevel angle and keep it as flat as you can.  I have sharpened adzes like this and it is simple and works great.  In fact, for many people this approach probably makes more sense than the approach I outlined above.

Sharpening a gouge.

Choices in sharpening are a matter of preference.  It helps to draw on skills that you have already developed through previous experience.  If you have experience freehand sharpening gouges on stones, then adopting that approach for an adze probably makes sense.  But if you are an avid turner who has extensive experience grinding spindle or bowl turning gouges, then you might prefer to hollow grind and hone the bevels, as I do.