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Through the years, I’ve admired butterfly patches (also referred to as dovetails, dutchmen, bowties, or pewas) in turned items. Except for turning into a major visible characteristic, they add worth to the piece by demonstrating the maker’s talent. Moreover, with the ability to flip a completed bowl with a crack in it extends your usable wooden stock.
Adapting to a Curved Floor
Butterfly inlays are frequent in flat work. Historically, the maker scribes round a hand-cut butterfly, drills or routs out many of the recess, then makes use of a chisel to work to the road for an ideal match. However I puzzled methods to switch that course of to the curved floor of a bowl. I used to be doubly impressed with turners who had used butterfly inlays in turned work.
The chance for me to study got here after I provided to restore a damaged bowl for a determined buyer. A bowl (made by one other turner) had been dropped and all however damaged in half. I researched varied strategies of restore and landed on the one I knew I may do with the instruments I already had.
I made a decision to make use of butterfly patches utilizing a router with an inlay guide-bushing set and a sample to make each the recess and the insert. I selected a distinct bowl as an instance the method on this article.
Notice that the grain of the butterfly inlay should run 90 levels to the crack to provide it full energy. If it runs the identical path, the butterfly itself may finally break. Often, I desire the butterfly to be of a contrasting wooden, however that could be a matter of desire. Select wooden that’s sturdy however comparatively straightforward to work by hand as a result of you’ll sometimes need to perform a little tweaking with a chisel or knife. I normally use black walnut for darkish patches and birch for gentle patches.
Router Concerns
I initially used an previous Craftsman router with good success, however its motor was typically misaligned, and it required plenty of care to advance the bit and preserve it in the identical relative place. Though the handles have been pretty excessive on the bottom, I didn’t discover it an issue, however after I tried a buddy’s small plunge router (making an attempt to unravel the misalignment difficulty) with even increased handles, I discovered it had a really “prime heavy” really feel and was exhausting to take care of wonderful management.
I made a decision to get a brand new router, a smaller one for ease of dealing with, with as a lot energy as my previous router, and handles as little as potential. Variable velocity and a gentle begin are additionally good options. However most necessary of all, it had to have the ability to keep on heart after I superior the bit. Whereas there have been a number of selections in the marketplace, I purchased a Bosch Colt.
Inlay Bushings and Router Bits
Inlay bushings are made to connect simply to most router bases, with the face flush to the underside of the bottom. A centered protrusion across the bit follows a sample and has a detachable collar that permits for detrimental and optimistic shapes (recess and insert). Depart the collar in place to create the recess, and take away it to make the insert. Earlier than you buy an inlay-bushing set, verify that it’ll work together with your router base. In my case, I used the lathe to show a customized router base from 1/4″- (6mm) thick acrylic, so it will settle for the bushing with an ideal match.
Whereas it will be potential to make the cuts utilizing a bit with straight flutes, spiral cutters make a lot cleaner cuts. Downward spirals go away a really clear lower on the floor however are inclined to load the recess with shavings. Upward spirals clear the chips higher, however they have a tendency to tear the floor of the wooden. So if you end up putting in a butterfly in a completed bowl, an upward spiral could be a poor alternative. My desire is the downward spiral cutter; I merely clear the chips between ranges of lower. Router bits can be found in 1/8″ (3mm) and 1/4″ diameters, so you should take that into consideration when selecting a detachable collar for an inlay bushing.
Make an Inlay Sample
So far as I can inform, all commercially out there inlay patterns are comprised of acrylic, so I had a buddy with a laser engraver make my first one. I discovered fairly shortly, nevertheless, that I wished extra sizes as a result of the inlays must be in proportion to the turned piece. In order that I wouldn’t need to consistently go cap inhand to my buddy’s store, I got here up with a straightforward technique of constructing the router patterns from wooden. Select a hardwood like exhausting maple, oak, or related.
A sample must be giant sufficient for the router to journey on it securely with out rocking. About 3″ × 5″ (8cm × 13cm) is sweet, as it’s going to work for many “bowl-size” butterflies and nonetheless present a secure platform. If you happen to needed to make a considerably bigger butterfly, think about growing the skin dimensions to take care of stability. I now make my patterns 3/8″ (10mm) thick, fairly than the extra frequent 1/4″, for 2 causes. First, I discovered (sadly, throughout an IRD) that as a result of the sample was barely thicker than the inlay bushing, the router teetered on the bushing on a small-diameter bowl, messing up the lower. Second, a thicker sample permits extra room for shavings, which helps to forestall build-up.
An inlay sample requires a prime, backside, and 4 heart sections lower to your most well-liked dovetail angle for the butterfly. After some trial and error, I selected to make my dovetail angles 15 levels.
Make a easy clamping machine and glue and clamp the parts, as proven. This picture exhibits the finished inlay sample, trimmed and able to use.
Rout the Inlays
As described earlier, the router bushing set has a detachable collar. Take the collar off, leaving the small-diameter “follower” when slicing inserts. Earlier than adhering the sample to the wooden with hot-melt glue, I put masking tape on each the sample and the wooden being machined. This enables for straightforward elimination of the sample and the hot-melt glue.
Rout as many inserts as you will get from a chunk of waste wooden, making them as thick as you need. I make mine a minimum of 1/4″ thick, from wooden that’s a minimum of 1/2″ to three/4″ (13mm to 19mm) thick. You’ll need to re-attach the sample for every insert. When you’ve got as many routed as you need, lower the inserts out on the bandsaw. If you happen to don’t have a bandsaw, this may be finished with a handsaw or desk noticed with a zero-clearance desk insert.
Rout the Recess
Butterfly inlays are usually “blind,” which means they don’t go all through the vessel wall. When you’ve got a thin-walled vessel, the place the butterfly does go proper by means of, bear in mind that the small quantity of handwork in fine-tuning the recess should be exact. Any cuts that aren’t 90 levels to the floor of the bowl can present up as a spot on the within.
I wish to re-mount the bowl on my lathe at an angle, utilizing the face of the chuck and the tailstock to place the work space as horizontal as potential. Decide the place you need the butterfly inlay, place the sample on the crack, hint across the within the sample with a pencil, then test to see if the form, orientation and proportions are to your liking.
Place masking tape exterior these traces in anyplace you count on to put hot-melt glue (normally the complete exterior dimension of the sample). I exploit blue painter’s tape as a result of it tends to adapt to the compound curve of a bowl properly.
Apply a spot of hot-melt glue on the two factors that type the “waist” of the butterfly, and safe the sample in place. As soon as it’s in place, glue wedges below the 4 corners, or wherever potential, to supply satisfactory help whereas routing.
Necessary: Watch out to take care of the angle of the sample in order that it’s tangent to the floor of the bowl. I normally have a number of wedges on the prepared, dry-fit them, then apply a dab of glue on the highest and backside of the wedges earlier than affixing them. Having lengthy wedges retains your fingers away from the recent hot-melt glue.
Butterfly inlays simply 1/8″ thick will present satisfactory energy, so I rout the recess a minimum of that deep, plus an allowance for any ending cuts on the bowl throughout turning. After setting the router-bit depth in order that it’s contacting the floor of the bowl, I put a chunk of tape on the router’s depth scale on the full depth to make it simpler to see. I like to make use of one of many corners for the “residence” nook, prolong the bit whereas the router is operating, then transfer the router clockwise across the sample.
You’ll want to take away any wooden remaining within the heart as nicely. I normally take a 1/8″-deep lower, take away the router to clear the chips, return to the house place, then decrease the bit the remainder of the best way. If you happen to can’t decrease the bit whereas the router is operating (like my previous Craftsman), prolong the cutter away from the sample and enter the lower someplace away from the sting earlier than shifting it to your own home nook. All the time let the bit come to a full cease earlier than eradicating the router from the sample.
After routing the recess, will probably be mandatory to chop the dovetail corners to a pointy angle, because the router will go away them rounded. Alternately, you could possibly go away the rounded corners as is, during which case you would need to not solely around the corners of the insert to match but additionally do all of the fine-tuning on the insert, not the recess.
Match and Glue the Inlay
Take a look at the match of the inlay within the recess to see which means it matches one of the best, then mark an “X” on one finish so you’ll at all times check the slot in the identical place. The inlay bushing creates a match that’s truly “too” precise, so the match should be relaxed a bit. Place the insert over the recess, hugging one aspect of the recess with one aspect of the insert, and scribe across the different aspect and each ends with a pointy craft knife.
Use that line to find the chisel to take off wonderful shavings as required. Alternately, you’ll be able to work the edges of the butterfly insert to regulate the match. It’s safer and permits larger accuracy to carry the insert with a clamp whereas making these cuts. You’ll be able to contact the ends on a belt sander or use your chisel. I’ve taken each approaches and have discovered that adjusting the recess is less complicated.
Chamfer the within edges of the insert to make for a straightforward entry into the recess. The match must be a pleasant push match or perhaps a faucet match. Don’t put all of it the best way in till you apply glue, because it most likely gained’t come again out with out harm.
Whereas cyanoacrylate (CA) glue is suitable, I desire common woodworking glue, as I really feel it gives a extra everlasting maintain. If potential, drive the inlay residence with a clamp, making a glue bond on the backside of the recess. Relying on the glue model you employ, clamping is normally required for an hour, with full energy in 24 hours. Nonetheless, there’s little or no stress on a well-fit butterfly whereas turning, so it’s cheap to show in an hour. I’ve by no means had an insert transfer throughout turning.
With common glue, there’s normally some squeeze-out into the crack. I attempt to “dam” the crack with a sliver of wooden to forestall that. You could possibly additionally take away the squeeze-out with a sequence of pointy blades, slivers of wooden, and/or dental picks. With the butterfly inlay glued in place, proceed turning the bowl as you usually would.
Closing Ideas
Typically, cracks that want a restore are apparent, however some aren’t. My feeling is that when the wooden’s moisture content material has reached equilibrium with the encircling environment, as with a roughturned bowl that has sufficiently dried, it is not going to transfer or crack additional. So if a crack is clearly minor, whereas others on the identical bowl have been patched, most individuals will perceive that the bowl will stay secure in its present state.
I’m typically requested if filling a crack (together with utilizing a butterfly) is a good suggestion. When you’ve got a salad bowl with a crack low on the partitions, filling the crack would preserve the bowl’s performance. However for extra aesthetic items, I would go away it unfilled. You may additionally simply merely wish to fill it. In both case, I might fill after inserting the butterfly, in case the location of the butterfly breaks the bond between the filler and the wooden.
Once I educate new turners, I emphasize the necessity to honor the wooden, to provide it their greatest effort. Utilizing butterflies to salvage a damaged piece or to utilize wooden with pure imperfections is a means of honoring the wooden. The Japanese name the artwork of repairing damaged pottery vessels kintsugi. Cracks are a part of the “surroundings” and historical past of a vessel and must be honored, fairly than disguised. A butterfly restore on wooden is not any much less engaging than figured grain and turns into a part of the story of a picket vessel.
Ed Fairly has been turning wooden for greater than sixty years, initially studying conventional spindle methods from his father. After retiring from a thirty-six-year profession as knowledgeable firefighter, Ed now turns full time. Ed gives an interactive distant demo (IRD) on crack restore in turned bowls. Study extra at edswoodturning.com.
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