Making Hardwood Lap Joint Boomerangs
By Dave Hendricks
Authorís notes: The construction techniques in this article use power tools such as band and table saws, and routers. These tools can inflict injuries if not used properly. Please use all normal woodworking safety procedures. Use push blocks and other safety items such as dust masks, goggles and hearing protection.
I am often asked about how I make various types of lap joint boomerangs. I was finally coaxed into writing an article. I am starting from scratch so bear with me if you are ahead of the class. My technique relies mostly on the table saw and router table however several other pieces of machinery also make their way into the mix.
Why make boomerangs from hardwood with a lap joint? The first boomerangs were made from natural elbows in tree or stumps. These boomerangs had the advantage of the grain of the wood running parallel to the wings of the boomerang, which provided strength. Most wood we buy today does not have the grain following the shape of the boomerangs we want. If fact, many "tourist" boomerangs sold in Australia are cut from boards with the grain running left to right across the face of the boomerang. This will result in a structurally weak boomerang. In order to utilize the wood commonly available to us, we must find a way to orient the grain along the shape of the boomerang. This requires adding a joint at the elbow or any other major change in direction of the shape.
The first thing you need is some wood at the correct thickness. I normally go for something about 1/4" to 5/16" (6 to 8mm) thick. I use wood 2" to 3" wide for normal shapes, 3" for triblades and 2" for quadriblades. When I make lapjoints, the more traditional boomerangs normally require two pieces at least 12" long, triblades need three pieces from 6 to 8" long and quadriblades need two pieces at a perfect 12". You can find some nice woods already at the right thickness by shopping at The Woodcraft Store at :( http://shop.woodcraft.com/), or you can do what I do, resaw it yourself. There are two ways to resaw; with the band saw or with the table saw. I use both. The band saw takes a smaller kerf giving more usable wood, but the table saw is more accurate at my house and I don't spend as much time sanding. See photo 1 for resawing at the bandsaw. Either way, I usually give the wood a trip to the sander or planer to make sure it is flat and even. I am fortunate enough to own a wide drum sander, which makes that work go so easy. One more way of obtaining thin wood would be to reduce thicker wood with a planer as in photo 2. A reminder, be sure you are working with dry and not green wood. I have included some additional dealers of thin hardwoods at the end of part one. I have personal experience dealing with The Woodcraft Store and Steve Wall Lumber. The savvy shopper can also obtain very nice thin woods on Ebay (see source below). Two things to watch out for when selecting pieces of wood for your boomerang are knots and extreme changes in grain pattern. Knots are sometimes difficult to work with, especially if they are located in the area you plan to route. Extreme changes in grain, such as burls and unusual curl, can often be weak points in the finished boomerang.
OK, we now have some wood and we are ready to go. Here is where we need to divide up the processes by which style boomerang we are making. We will start with traditional shapes, so you multi blade fans need to wait until Part Two of the article. The first thing you need to do is cut the angle you wish the elbow to be. If you decided that a 90 degree angle is good enough, you can cut the pieces off square, otherwise continue on. I estimate the angle by laying a template of the final shape (or a boomerang used for a template), on my table saw and eyeballing a cut right through the elbow. (The boomerang's elbow, not mine). See photo 3. I lock my miter gauge and make the same cut on both pieces of wood (not the boomerang). I should note that I have attached a wood extension to my miter gauge, which allows me to use stop block to make the pieces exactly the same length and also allows shorter pieces to be cut at a greater angle. Otherwise the piece may not reach the blade. When you are done flip one piece over and overlap the pieces at the elbow, the result should be the correct angle as in photo 4. While you have the saw set, cut a piece of scrap wood with the same angle to use as a push block during routing. Photo 5 shows two cut strips and a pusher piece. Make sure that piece has parallel sides before cutting. I now have several pieces at different angle that I reuse. This makes the set up easier for the next time. Two angles I frequently use are 18 and 22 degrees. I keep a push block for them handy and use it to set my miter angle. Photo 6 shows how you can obtain a different shaped boomerang reversing the angle on the cut pieces.
Now it's time to get out the router table. Mine is an old Craftsman table with matching router. I use a 1/4"' shank, 1/2" diameter straight bit to cut the laps. First, I use a straight piece of wood for a fence and attach it to the table behind the bit. I make sure that the distance from the fence to the front edge of the bit is the same as the width of the wood I am using as in photo 7. I then set the router bit depth to just a little less that half the thickness of the wood like photo 8. Using the push block I made earlier I make the first pass in the wood at the maximum width I set. Photo 9 shows the push block behind the strip I am routing. I then cut the remaining wood out by backing the wood starting at the end of the board and working my way to where I made the first cut. Using the backing board and cutting the first pass like that, helps prevent tear out as I complete the cut. I then cut the second piece the same way resulting in two identical pieces.
Photo 10 shows a piece with just the initial pass through the wood and another with the rest of the wood removed with "waste cuts". After I have routed both pieces, I flip one over and match them at the elbow to see how close I got the depth of cut. See photo 11. Since I started at a less than half depth, I am pretty sure I need to cut deeper. I can make fairly small adjustments on my router depth so I just set the bit slightly higher and make another cut. Now I only rout one piece before checking how the two match. If more cutting is needed, I then do the second one. Often I don't get the depth perfect and by cutting one at a time and checking the depth between cuts, I can get a more perfect match without cutting too deep. It is also good to keep cut off pieces from making other boomerangs, as they are handy to use to test the depth of cut before committing to cutting the real stuff.
From here on, the going gets easier. It's time to glue the pieces together. Before gluing, I inspect the two parts to make sure the routing I did is fairly smooth. Often when making multiple passes with the router, you get some small ridges or fuzz in the cut. In photo12 you can see how I use a wood chisel to make sure the cut is cleaned up. You can do this with sandpaper but be careful. It is easy to round the outside edges and make the joint worse, not better. After cleaning up the area to be glued, you now have pieces ready to glue up into blanks. Photo 13 show a stack of pieces ready to go.
Mix a small amount of epoxy according to the manufacturer's direction. Apply it to both pieces, making sure you get it in the corner of the cut. Flip the one piece over and attach it to the other at the elbow. Use a couple of small cl@mps to hold them until dry. I usually use spring type cl@mps as in photo 14. When the glue is dry, you are ready to make a boomerang.
Remove the grips and get out your pattern (or the boomerang you used as a pattern). At this point, you can lay the pattern on top of your glued blank and just trace the pattern directly on the wood. Photo 15 show two blanks already traced and another with boomerang of the proper shape to trace the third blank. Using a band saw, scroll saw, jigsaw or even a coping saw (by hand), cut the blank into the shape of the pattern. You are now ready to sand.
Sanding or shaping of the boomerang follows the normal way you have done it with plywood. A word of caution, some wood has the tendency to leave burn marks if it is sanded to hard or too fast. These require quite a bit hand sanding to remove. I notice this in cherry, harder pieces of maple, ash, and quite a few of the exotics that seem oily (rosewoods for instance). Bubinga and purpleheart are also easy to get burn marks on them.
Once you have sanded it to your satisfaction, take it out to test it. Because of the various densities of different wood, your boomerang may not fly like the original pattern. Testing is needed to confirm the flight characteristics of each boomerang. If it performs well, head to the shop for final finishing. This is one of my favorite times. That first coat or two of finish is what really allows you to see the beauty of the wood. Spray polyurethane works pretty well as does tung oil (see below). I give a light pass of clear to seal the boomerang and then sand a gain. The clear helps "stiffen up" the fuzz and fibers of the wood and allows you to produce a better finish in the end. A couple more coats of clear, with some sanding in between should get it looking good. Use progressively finer sandpaper to achieve a fine finish. When done, sign and date it and write what wood was used on the back of the boomerang. You now have a finished, hardwood lap joint boomerang like the ones in photo 16.
The alternative approach to finishing natural wood boomerangs is also one I prefer. I start by sanding the boomerangs to the best I can. I then apply coat of Minwax Tung Oil finish. After that dries 24 hours, I take some 00 steel wool and sand the entire boomerang. I apply another coat of tung oil and allow to dry 24 hours. Again I sand it using the steel wool and apply another coat. Usually four coats will give a glossy, full finish. For the first several coats of finish, I do the entire boomerang, front and back. I lay the boomerang on brown paper bags to dry, sometime using a piece of dowel to support it. For the final coat, I prefer to do the back first and after it is dry, finish the front.
Continue on to Part 2!
Changes last made on: September 13, 2017