Monday, September 2, 2013


I've been turning a large batch of handles for the reamers that I make over the course of the past few days.  To accurately size the portion of the handle that locks into the body, I use a rounder plane like the one pictured above.  My rounder is made from a block of wood and a Stanley frog and blade assembly (á la Pete Galbert) from an old handplane.  It works great, precisely creating the joint that I need time and time again.  While this seems like an intuitive assembly to put together, it can be tricky to get it to work properly. 
The first one that I made required so much force to turn the spindle through the cutter that it tore up my hands and aggravated my forearms every time that I used it.

When cutting with gouges and skew chisels on the lathe it is important to present the edge of the cutting tool with minimal clearance of the bevel.  This ensures that you are cutting and not scraping the wood away, which tends to leave a better finished surface and reduce resistance to the forces of cutting.  The same principles apply to rounder planes.  The cutting edge should be presented to the workpiece at an angle just high enough to prevent the back of the bevel from rubbing.  In the picture below the blade has a 30 degree microbevel, which means the iron must be bedded at an angle slightly greater than 30 degrees to prevent the back of the bevel from interfering with the cutting action.  In this example the iron is bedded at 35 degrees.

Note the low clearance angle of the bevel.
The low clearance angle reduces the effort needed to cut the spindle.  If you have ever used a low angle block plane (especially on endgrain) you have probably noticed how it seems to slice through the fibers with less effort than planes with blades mounted at higher angles (typically 45 or 55 degrees).  Keeping the angle of attack as low as possible in a rounder plane translates to faster work, less effort, and forearms that won't be screaming at you when you pick up that third chair leg to cut the tapered tenon on top.

5/8" hole.

With this knowledge, the process for making a successful rounder plane is straight forward.  Start with a block of wood roughly six inches long and as wide as the blade you will be using as the cutter.  Drill a hole the size of your finished spindle or the top of your leg through your block and ream the hole to the desired profile.  My example is a 5/8" hole with a six degree taper in the first 3/4" of the hole.

Reaming taper in the first 3/4".

I do the reaming for holes like this by holding the reamer in one hand and the workpiece in the other.  The only reference you have to be sure you are going straight is that the end of the reamer coming through the hole remains centered.  I actually watch that end as I turn the reamer to make sure that I stay centered.

Reamer centered as it exits the hole.

With the hole reamed to the finished profile, remove all but the last sliver of wood above the hole.  I use a bandsaw and fence to remove the bulk of the waste.

Bulk of wood removed.

And finish by planing off the last sliver of wood until the hole just begins to show through the surface, as pictured below.

I trim the last fragments of wood from the opening with a knife or saw.  If you have ever made a wooden handplane this begins to look a bit familiar.

Place the frog on the surface of the wood.  Note that if you tilt it up so that the front portion of the frog sits level on the wooden block, the blade protrudes into the hole instead of resting at a point on the circumference of the hole.  The frog must be tilted back, which simultaneously pulls the blade up out of the hole and lowers the clearance angle, as addressed above.

Blade extending into the hole.  Frog must be tilted back.
The standard angle frog positions a plane blade at 45 degrees to the sole of the plane.  For my purposes I want the blade to be bedded at 35 degrees.  That means that I want to subtract 10 degrees from the existing 45 degree frog, to achieve my 35 degree bed angle.  To permanently adjust the bed angle add an angled riser block that tilts the frog 10 degrees back.  Cut a 10 degree wedge the same width as your frog, with a maximum thickness of about 5/8".  Smooth the top and bottom surfaces of the wedge with a handplane and position the wedge on the block underneath the frog with the blade assembly roughly centered on the opening.  To properly fit the riser block, saw off the front of the riser in 1/8" increments (or less) until the elevated machined portion of the frog sits flat on the wedge shaped riser block as pictured below.

Frog properly seated on riser block.

One clamp provides enough pressure to glue the riser block in place.

Riser block glued in place.

After the glue has set up reposition the frog on the block.  If the frog rocks back and forth, fine tune the bedding surfaces with a plane to remove the offending high spots.  With the frog solidly bedded remove the blade assembly and mark the holes to attach the frog to the block.

Holes marked for drilling.

Drill a few test holes to find the appropriate pilot hole size for the screws that originally attached the frog to the plane's sole (3/16" worked for mine).  The holes should be drilled square to the sloping surface of the riser block.  I drilled the pilot holes on the drill press by shimming underneath the block until the sloping riser block was square to the drill bit.

Pilot holes drilled.

Attach the frog to the block.

Frog in place.

My default method of problem solving is heavy on the math.  I love calculating angles and using trig functions to describe the details of what is happening on my workbench.  The first time I made I tried to walk down the geometry road to figure out the ideal shape of my blade in relation to the bedding angle.  My thoughts went something like this, "If I grind a 6 degree taper on the last 3/4" of the blade and the blade is bedded at a 35 degree angle, the assembly will actually be cutting a taper of...."  After about five minutes down that road my brain exploded and I switched to a trial and error approach to blade shape and position.  You will know if the assembly is not working right.  Try to figure out where the spindle is binding or why the blade is cutting to much.  Play around with the depth of cut adjustment, amount of skew, and blade shape.  Also, move the frog forward and back until you find a sweet spot where the assembly cuts the desired shape and the amount of force necessary to turn the wood through the cutter does not tear apart your hands and forearms.

Test piece.

For joints that have a taper and a straight section you will need to grind the blade to the appropriate profile.  For joints that are a straight taper you will have to attach the riser block at an angle (it should be half the angle of your total taper) to appropriately position the blade.

Blade with tapered and straight sections

Once the frog and blade are properly set, the rounder produces repeatable, perfect joints.  I turn my reamer handles very close to their finished size and remove just the last, little bit of material with the cutter.  This produces the cleanest results and it minimizes the wear and tear on my forearms.

Perfect joints every time.