A while in the past, I spent a morning instructing turning fundamentals to a novice turner. She left with the primary bowl she had ever turned, and as a thanks, she gave me a bread knife she had made with a scroll noticed. It was constructed from two items: a bow for the blade and a deal with screwed to the underside of the bow.
My spouse fell in love with it. Her solely remark was she wished it have been turned. I checked out it and thought I might flip a one-piece model, however the venture would current a few fascinating challenges.
As a result of the deal with is offset to permit your knuckles to clear the slicing board, I must make a two-axis turning. The primary axis turns the bow spindle and the second turns the deal with. As well as, after shaping the bosses (or arms) — one on the top of the bow spindle and one between the bow spindle and the deal with — a jig could be wanted to bend the bow spindle in order that when the blade is screwed on, it might have adequate pressure for slicing. The knife blade itself is well bought from any of quite a lot of on-line sources.
Supplies and Structure
Your selection of wooden is extensive open. I began working towards on a humble piece of dimensional 2×4 pine, which made a really nice-looking bread knife. Subsequently, I’ve made them from walnut, ash, and cherry, with cherry being my favourite. This venture is constructed from a chunk of hardwood 1-1/2″ × 2-1/2″ × 18″ (38mm × 6cm × 46cm). The utmost thickness of a slice of bread lower with this knife is decided by the 1-1/2″ beginning width of the clean. To chop a thicker slice of bread, begin with a thicker clean, say 1-3/4″ (4cm) extensive.
As introduced, this venture makes a right-handed knife. Assuming the left finish of your wooden clean is the bow finish and the suitable finish is the deal with finish, orient your clean in order that the shorter sides are horizontal. On the left, or bow finish, mark 45-degree strains from the underside left and prime proper corners. For the decrease left diagonal, measure 1/2″ (13mm) from both edge, mark this level on the diagonal line, and center-punch an indent to mark the bow’s turning axis. For the highest proper diagonal, mark 5/8″ (16mm) from both edge, carry the road onto the diagonal, and punch an indent to mark the deal with’s turning axis.
Now lay out the corresponding axis factors on the deal with finish of the clean; the bow’s axis level is within the decrease proper, once more measured up 1/2″ from both aspect, and the deal with’s level is within the higher left, 5/8″ from both aspect. This fashion, every pair of axis factors stays in a single axis, offset from and parallel to the middle of the clean.
When turning offset objects, you have to confront three points: lathe velocity, contact, and security. Generally, clear cuts require that you simply function the lathe as quick as attainable with minimal vibration. However as a result of the wooden is offset and therefore out of stability, as you enhance the velocity, the vibrations start to extend. Furthermore, because the offset passes the slicing fringe of your device, you’ll then be “slicing air” till that revolution is full and the wooden once more comes into contact with the device. So you’ve two components working to lower stability and degrade the standard of your cuts. However there’s a manner round this. As you enhance lathe velocity, the vibrations enhance, enhance, then lower. This primary peak of vibrations is named the primary harmonic. You’ll be able to both again the velocity down barely to clean out the spinning or enhance the velocity previous the primary harmonic to the sleek vary earlier than the second harmonic. As well as, sooner rotation means much less time slicing air. Once you discover that candy spot in velocity, the result’s much less vibration, much less device chatter, and cleaner cuts.
Whereas velocity might help clean out your cuts, you continue to need to use a lightweight contact. Aggressive slicing would imply that in the course of the slicing air portion of every revolution, your innovative would advance appreciably. When the device once more encounters the wooden, this normally ends in a nasty catch or a piece of wooden flying off. Not like in regular turning the place aggressive slicing ends in a deeper lower, offset turning calls for a extra affected person and incremental strategy.
Lastly, any offset turning dangers busting your knuckles. These spinning offset corners flip into ghosts, however they’ll most assuredly rap you exhausting in case you drop your guard and lose monitor of the place they’re. And, very true for offset turning, all the time put on an impact-resistant polycarbonate faceshield; chemical splashguards won’t defend you from impression.
Flip Two Tenons
For my first try, I merely positioned the clean between facilities utilizing a steb drive heart and a dwell heart with a degree within the tailstock. This required sufficient strain from the tailstock to power the drive heart to “chunk in.” However I found the strain brought about the spindle to deflect barely as I decreased its diameter. Plenty of sanding was required to scrub up the ensuing device marks. What labored finest was to show offset tenons on each ends of the clean. That manner, I might use a chuck with step jaws to interact the tenon and drive the wooden.
Begin with the handle-end tenon first (on the suitable finish of the clean). Mount the clean between facilities on the deal with axis factors. Utilizing a really sharp parting device, start taking very mild peeling cuts to type a roughly 3⁄16″- (5mm-) lengthy tenon on the tailstock finish of the clean. Scale back the diameter till you’ve a cylindrical tenon, roughly 1″ (25mm) in diameter.
As a result of turning the handle-end tenon removes the marked bow spindle axis level on the suitable finish, you’ll have to put out that axis level once more. Subsequent mount the clean between facilities on the bow spindle axis factors and, utilizing very mild cuts, type a similar-length tenon on the drive finish of the clean, roughly 3/4″ in diameter.
Now you’re able to mount the clean within the chuck and start turning. Place the bow spindle tenon within the step jaws, and advance the tailstock dwell heart into the bow spindle axis level on the deal with finish. Mark reference strains 1″ and 10″ (25cm) from the bow spindle tenon shoulder to map the size of the 9″ (23cm) bow spindle.
Then mark reference strains 13″ (33cm) and 17″ (43cm) from the bow spindle tenon shoulder to outline your deal with size. Make strains lengthy and darkish sufficient to see whereas turning. A storyboard makes format faster and simpler.
Flip the Bow Spindle
Fastidiously modify the toolrest to clear the offset clean. Improve the velocity of the lathe to simply under or above the primary harmonic to reduce lathe vibration. Utilizing a bowl gouge, start forming the inside faces of the bow spindle bosses on each ends. Keep in mind, lower very calmly to keep away from tearout or catches. In case you are a newbie, apply turning with each left- and right-handed approaches. That is one of the best ways to “open” these bosses. Consider it as hollowing a bowl. However watch out for the wings on the gouge, as they will catch on the other aspect from the place you’re slicing.
If the gouge is held vertically with the slicing find yourself and flute dealing with you, consider an analog clock face with 12 o’clock on the prime of the deal with. Most of my slicing is on the bevel between 11 and 1 o’clock. To outline the bosses on every finish, I primarily lower a pointy, deep cove, slicing down from the excessive level to the underside of the curve on both aspect. Make the boss faces as vertical as attainable with very clean, clear cuts.
Utilizing both a bowl gouge or a spindle-roughing gouge, take away the offset waste between the bow spindle arms. I exploit a smaller roughing gouge to scale back the prospect of a catch. Improve the lathe velocity if attainable and proceed shaping the bow spindle till it’s roughly 3/4″ in diameter.
I exploit a peeling lower with a parting device to scale back the diameter to dimension within the center and close to every arm. These reference depths assist me receive a constant diameter throughout the complete spindle. Lay the knife blade throughout the bosses to make certain the span is extensive sufficient (don’t ask how I do know that). If the span is simply too brief, lower extra from the deal with finish boss. Form the bow spindle as desired, however don’t go thinner than 1/2″ diameter. You now have a cleanly outlined spindle between two comparatively coarse bosses. Sand the bow spindle and inside faces of the bosses, then apply sanding sealer if desired.
Flip Deal with
Subsequent, you’re prepared to show the deal with, however keep in mind that turning the bow spindle tenon eliminated the left deal with axis level. As above, lay out the deal with axis level reverse the deal with tenon. Reverse the clean and place the deal with tenon within the chuck and the dwell heart within the reverse hand level. Repeating the method you used to form the bosses across the spindle, start shaping the boss dealing with the deal with, then form the deal with. If you end up happy with the boss and deal with, sand whereas nonetheless on the lathe and apply sanding sealer if desired.
To hurry up the turning course of, you possibly can make the most of a bandsaw with a skinny blade to take away the waste earlier than shaping the bow spindle after which earlier than shaping the deal with. However right here I selected to show away the waste to show the offset turning.
Now you’re prepared to start the ultimate shaping. Utilizing a bandsaw or coping noticed, take away and roughly form the outer floor of the boss on the bow finish of the spindle and take away the waste on the deal with finish.
I exploit an influence disk sander to finish shaping the surface of the boss on the bow finish and to refine the top of the deal with. Soften all edges besides the blade mounting space. In any case sanding is accomplished, lay the blade throughout the bosses, even with the underside of the knife, and mark the placement of the bow-end screw. Take away the blade, drill a pilot gap and screw one of many mounting screws into the opening, leaving it about 1/8″ (3mm) proud. This lets you wrap a string or piece of wire across the screw to make a hanger for ending. I spray the wooden with a transparent gloss lacquer, then buff to provide an excellent look and clean, waxed really feel.
For the knife to chop bread, it has to have the blade mounted below pressure, like a metal-cutting hacksaw. Initially, I hooked up the blade by tightening the screws at an angle to realize pressure. This didn’t produce the required pressure, so I designed a bending jig so the blade may be hooked up with the spindle flexed. When the bend is relaxed, the blade shall be below pressure.
I used dimensional 2×4s to make the jig. Drill a 2-1/2″-diameter gap within the heart of an 18″-long 2×4. Then lower the wooden in half to make the 2 risers with cradles on prime. These 9″-tall risers are screwed to a 12″ (30cm) base; the unfold permits the bosses of the completed knife to relaxation within the half circles. Leather-based glued to the 2 cradles protects the end on the knife bosses.
On the midpoint of the bottom, mount an eyebolt in a through-hole with a recess on the underside, utilizing a locking nut and washer on the highest and a nut and washer on the underside. Connect a turnbuckle with a hook on one finish to the eyebolt. The “eye” finish of the turnbuckle has an S-hook positioned by means of it. The opposite finish of the S-hook, coated with heat-shrink tubing to guard the bow spindle end, pulls down on the middle of the bow spindle.
To mount the blade, place the bosses within the cradle with the blademounting flats dealing with up. Place the S-hook over the middle of the bow spindle and tighten the turnbuckle till finger tight. This can barely bend the wooden. One finish of the blade is screwed to the opening already drilled within the bow spindle finish. Mark the placement of the opposite blade gap on the deal with finish of the bow, drill a pilot gap, and connect the blade with the second screw. All of that is carried out with the spindle bowed and below pressure. When the turnbuckle is loosened, the blade ought to “sing” because of the ensuing pressure, and the finished knife is able to slice bread.
For a left-handed model of this bread knife, reverse the orientation of the deal with and spindle axis factors throughout format.
Paul Coppinger is a local Texan who turned his first piece within the ninth grade and nonetheless has it. Following a profession in electrical engineering at Texas Devices, Paul has turned his full consideration to woodturning. A member of the East Texas Woodturners, he has introduced at numerous golf equipment and teaches in his store. Throughout all kinds of labor, Paul explores embellishment strategies and strives for the proper end.