Paul Chilton: Peppermills

Preparing the Blank

Wood selection and preparation is important in turning a pepper mill. It is essential that the wood be thoroughly dried before turning. Woods that have interesting grain figuring are most desirable. High figure is usually found near the base of the trunk or in the area below a crotch. When cutting blanks from a log it is wise to cut 4" × 4" billets of suitable length with the grain orientation aligned with the long axis of the billet. Drying can be enhanced by roughing the billet into a cylinder and waxing the end grain with log sealer. The rough cylinder(s) can then be air dried where not exposed to sunlight, heat, or strong air movement. Paul starts his wet cylinders on a shelve near the floor and moves the cylinders to successively higher shelves as drying progresses so the driest wood is near the ceiling where temperatures tend to be higher. The point is to control the rate of drying. Slow drying is less likely to cause splits in the wood.

When a blank is thoroughly dry and ready to turn, examine the grain and color figuring and decide on the shape and configuration of the mill to be turned. Mount the blank between centers and turn to a true cylinder with a spindle roughing gouge. True up the ends of the blank with a spindle gouge to ensure both ends are true and square. The trued blank Paul created in this demo measured 3-1/2 inches in diameter and 10-1/2 inches in length.

Lay out the dimensions of the top (head) and bottom (body) sections of the mill. In this demo Paul chose 2-1/2 inches plus a 5/16 inch tenon for the head section and 7-1/2 inches for the body with 3/16 inch allowed for a parting gap to separate the two sections. Where grain matching is an issue it is wise to minimize the parting gap. Use a thin parting tool to separate the two sections taking care to keep the cut as clean and square as possible since those faces will bottom out on the 4-jaw chuck later.

Caution: Never part all the way through a piece between centers. Doing so can cause the two pieces to bind on the parting tool and explode out of the lathe. Part down to a safe diameter and finish the cut with a fine tooth saw with the lathe not turning.

Boring the Holes

Mount the body section in a four-jaw chuck with the parted face toward the chuck. With the parted face firmly and squarely in contact with the bottom of the jaws, no tenon is needed. Throughout all the chucking and re-chucking steps it is important that any detected wobble be corrected so that all parts of the mill will remain concentric and true. With a spindle gouge true up the exposed bottom face of the body section and true up the cylinder for about an inch above the face. This will give a sure mount when the body section is reversed in the chuck later. The bottom face of the body should be turned very clean and slightly concave since the finished mill will stand on the outer edge of this face. Cut a small dimple in the true center of the face to help center the bit in the following drilling step.

Mount a 1-5/8 inch Forstner-type bit in the tail stock. With the lathe turning at 500-700 rpm bore a 1-5/8 inch diameter hole into the base 3/8 inch deep. Enter the cut very slowly to ensure the bit remains on true center without wandering.

Note: Paul has created wooden shields to protect his bits when not in use. He has used the bit to be stored to bore into a cylindrical block, cut the bored cap to a desirable length, and simply inserts the bit into the bored hole so the cutting edges rest against wood inside the hole and are completely protected from accidental contact with hard objects.

Next, mount a 1 inch Forstner-type bit in the tail stock with a bit extension. Selection of a bit extension is important. The shaft should be the maximum diameter permitted by your bit chuck (preferably 1/2 inch) to ensure rigidity and the female end should be the same diameter as the shaft of the Forstner bit so the bit will remain on true center, not offset by a sloppy fit in the set screws. Beginning at the bottom of the 1-5/8 inch hole already bored, slowly advance the 1 inch bit into the wood and continue boring along the axis of the blank. The depth of the new hole must be at least half the length of the body. Advance the bit steadily as long as chips continue spilling from the hole. When necessary, back off to clear the hole and the bit then advance the tail stock and continue boring. Don’t allow chips to pack around the bit. That would cause excessive heat and poor cutting. In this demo, Paul made this cut 4-3/4 inch deep. Use a skew (with shaft corners relieved) to clean up the wall of the 1-5/8 inch hole taking care to keep the tool parallel to the lathe bed. With the lathe turning at fairly low speed, use the skew to open and clean the 1 inch hole to 1-1/16 inch to receive the milling mechanism. Test the fit with the mechanism to ensure you don’t make the hole too wide. Using excessive speed for this cut tends to bind the shavings against the interior wall so they interfere with the cut. Sand the base face and lightly sand the wall of the 1-5/8 inch recess. Using the skew as a scraper, flatten and clean the shoulder between the 1-5/8 inch and 1-1/16 inch holes. For this cut Paul used a 3/8 × 3/8 beading tool that he had ground with rounded sides for clearance.

Remove the body section from the chuck and reverse it so the base face is firmly and squarely against the bottom of the chuck jaws. This exposes the top end of the body. True up that upper face with the spindle gouge so the face is dead square or very slightly concave. Make sure this cut is very clean. Mount the 1 inch bit and extender in the tail stock and bore through to meet the previous boring. Again, enter this cut very slowly to allow the bit to center without wandering. Boring from both ends to the center minimizes bit wander and also hides any misalignment of the holes in the center of the body. More importantly, it ensures the upper end of the hole that will receive the head tenon will be concentric. Clean up the upper end of the hole with the skew being very careful to keep the tool parallel with the lathe bed. The diameter of this hole is not critical, but it is essential that it be truly cylindrical and the walls be parallel with the axis of the body so the tenon will not bind or wobble. Lightly sand the interior of the bore. A convenient tool for sanding the deep hole is a 5/8 inch sanding drum mandrel mounted in drill bit extender with a handle. This allows you to sand deep into the hole without putting fingers in jeopardy. Also sand the upper face of the body out to about 1/2 inch from the hole.

Remove the body section from the chuck and set an outside caliper to be just slightly larger than the finished bore at the upper end of the body to approximate the diameter of the tenon to be cut in the head section. Mount the head section in the four-jaw chuck with the parted face (bottom) exposed. True up that face with a gouge and cut a 7/8 inch diameter recess to receive the drive plate of the mill mechanism. Paul used a 7/8 inch Forstner-type bit in the tail stock to cut this recess about 1/8 inch deep. Then use a 17/64 (or 7 mm) drill bit to bore a hole to receive the drive shaft of the mechanism. This hole will pass through the center of the drive plate recess through the length of the head. Again the hole is to be drilled from both ends toward the center, so this first drilling should pass at least half way through the length of the head section. Use a skew to carefully open up the 7/8 inch recess with a very slight taper to just fit the drive plate. With the skew, flatten the bottom of the recess so the plate rests firmly on the bottom of the recess.

Use a parting tool to rough out the tenon on the bottom of the head section that will fit into the hole at the top of the body section. Make the first cut just half the intended length of the tenon to minimize waste if an error is made. Make the rough cut down to the diameter measured by the preset outside caliper. Cut a slight chamfer on the edge of the tenon and test fit the tenon into the hole in the body section. Proceed gradually until a snug fit is found, then extend the tenon to the desired length. Use a very sharp parting tool to clean up the tenon with a pure scraping cut so that the tenon can turn smoothly without wobble in the body. Carefully clean up the shoulder down to the tenon making the shoulder dead flat or very slightly concave. The corner between the tenon and the shoulder can be cleaned up with a point tool or small gouge. Sand the face of the shoulder out about 3/8 inch. Touch the tenon lightly with 320 grit sandpaper so the tenon is clean and turns freely but true in the body.

Remove the head section from the chuck and reverse it gripping the piece so the shoulder rests firmly on the bottom of the jaws. True up the top face of the head section with the gouge. Then use the 17/64 drill bit to drill through to the previously drilled hole. This will complete the passage for the drive shaft. Remove the head section from the chuck.

Shaping the Mill

Replace the four-jaw chuck with a chuck mounted with extended pin jaws. Mount the body section on the pin jaws with an expansion grip in the 1-5/8 inch recess at the base of the body. Use a large cone center in the tailstock to center on the hole bored through the upper face of the body. This set up ensures that the body is mounted with the center of the borings as the true axis of the lathe. True up the cylindrical body section if necessary. Use calipers and a parting tool to mark the critical diameters of the body profile. These include the maximum diameter at the waist, the minimum diameter at the throat, and the diameter of the flare at the top of the neck. In this demo, Paul chose the waist diameter to be virtually the full diameter of the blank (about 3-1/4 inches), the throat diameter to be about 1-5/8 inches, and the flare diameter to be about 2-1/8 inches. A spindle gouge is used to remove waste wood from the flare to the throat, from the waist to the throat and from the waist to the base. This establishes the rough profile of the entire body. Using smoothing cuts with the spindle gouge, refine the shape of the body. Make these cuts as cleanly as possible to minimize sanding. Paul used shear scraping cuts near the tip of the gouge for the tiny final adjustments and smoothing. Paul also chamfered the top edge of the flare. Back off the tail stock and cut a circular gasket or shim from a single layer of paper towel. The diameter of this shim must be just a bit larger than the diameter of the hole receiving the tenon so when the tenon is pressed into the hole covered by the shim there will be contact with the shim only on the end and side walls of the tenon and none in the joint between the faces of the body and the head shoulder.

With the head and body joined tightly with the shim, return the tailstock and cone center into the 17/64 inch drive shaft passage at the top of the head. Apply just enough pressure with the tailstock to hold the head and body together soundly. Shape the head profile with the spindle gouge. The maximum diameter of the head should be slightly (3/16 inch) smaller than the diameter of the waist of the body to avoid a top-heavy appearance. Great care must be taken when shaping the bottom curve of the head so that the bottom edge of the head and the upper edge of the chamfer on the body flare align perfectly and at symmetrical angles. The upper curve of the head should terminate with a flat surface of the same diameter as the acorn nut that caps the drive shaft of the mill so there will be no visible gap between the nut and the head.

Finishing

The entire mill can now be sanded progressively with grits through 600 and buffed lightly with 0000 steel wool and paper towel before applying finish. Paul recommends using a penetrating finish on the exterior since the mill will experience much handling. He uses paper towel to apply a coat of slightly thinned urethane oil (9:1) and rubs the application in with the lathe turning until the finish is absorbed into the wood. He then removes the mill from the lathe and sets it aside to dry until all solvent odor is gone. He remounts the mill in the lathe for second and possibly third applications following the same procedure. The third application will be very light. After thorough drying the mill is buffed with paper towel.

Paul also recommends that no finish be applied to the interior of the mill since odors and flavors in that closed space are very persistent. A little lemon oil wax might be helpful on the area around the tenon and the bottom recess of the mill.

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Demo illustrations...

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