Bevellok.com

Convert your favorite old one-piece longbow or recurve into a two-piece take-down 

Probably every one of us has wished our favorite old one-piece was a bit shorter when it came time to pack for that long awaited bow hunt to some distant mountain or river bottom. Just such an occasion led to a fairly simple conversion technique that will allow you to carry that same old bow in your duffle bag.

The secret to ending up with the bow you started with is to capture it as a one-piece and use the same fixture to put it back together. If careful measurements are taken before the bow is cut and are then reestablished during the reassembly, it will turn out to be the same old bow, only jointed.

Anyone who is a bit of a do-it-yourselfer can handle the job without too much effort and with pretty common equipment.  If you don’t have some of the tools, there is probably a handyman in your archery club who might like to tackle the job with you.  It might even be the sort of project the club might be interested in doing together.   So, lets go over the tools and supplies you will need.

A solid workbench or other surface that is longer than the bow.   A rail three or four inches high that is the same length as the bench.  Several C-clamps of various size.   A jigsaw.   A handheld router with various bits.   A miter box.   A power drill and bits.  Two pieces of plywood long enough to extend past the fadeouts on your riser and wide enough to extend an inch or two beyond the back and belly.          A piece of 1”x 3”strapping as long as the plywood.   Saran Wrap.   Spray foam insulation.   Carpenters glue.  Bevellok bow Joint hardware and fasteners.  Bedding epoxy (Smooth-on MT-13)

Once these items are gathered you are ready to begin the layout for your bow jig.

After determining the joint location, trace the contour of the riser, back and belly, from fadeout to fadeout on a piece of poster paper. Cut the template as shown and transfer the tracing to one of the pieces of plywood   

Next, clamp the two pieces of plywood together and cut the back outline of the bow with the jigsaw. Then attach each piece of plywood to the opposite edges of the I”x3” strapping.            Note: The strapping can be ripped to more closely fit the width of the bow.

The completed box will look something like this. Notice the tracings of the bow belly and joint outline have been laid out on the side of the box. Also, note the wedge shaped supports cut to the contour of the riser at the fadeouts and glued in both ends of the box.

Next, position the bow in the box so that all the tracings on the outside of the plywood align with the markings on the bow. When you are satisfied that all the markings will correspond with each other, wrap the riser section with Saran Wrap and clamp the bow in the box as shown. We inserted pieces of tire tube rubber to protect the bow and clamped it in place with small blocks of plywood and drywall screws. The pressure is applied directly over the fadeout wedges referred to earlier.

The next thing is to secure the bow in the area where the inletting and cutting is to take place. To do that we are going to inject the box with expanding foam. To make certain the foam does not push the box or bow out of shape, tie the top of the box together with a section of aluminum sheet metal. It is important to keep the tang area open to allow for the routing operation. Once the sheet metal is in place, drill a few relief holes along the bottom of the box and inject the foam. Set the bow aside and allow the foam to cure overnight.

When you return to the project, shave all the excess foam from the outside of the box and get ready to begin the inletting. The bow is now securely captured from fadeout to fadeout and has flat and true surfaces to work from and to. The first operation is to inlet for the joint tang along the centerline of the bow's back. That is done by clamping a guide rail on the bottom of the router base and adjusting it as to align the center of the bit along the centerline of the bow. Start with a 1/2" bit for the first pass and do not try to go too deep. Each subsequent pass will be a little deeper until you have reached the desired finished depth as laid out on the outside of the plywood. Next, change to a 5/8" bit and repeat the process to the same depth. Note: use carbide bits as you will be plunging through a variety of laminations. It is also a good idea to extend the length of the slot 1/8" or so to be sure there is plenty of room for the joint during reassembly.

The time has now come to cut your bow in two. Place the bottom of the box against the rail of a power miter box and align the blade with the cut line laid out on the outside of the plywood. Remember that the line is the centerline of the cut so the blade should be centered on it. I usually cut a scrap of plywood first and lay that on top of the box to be sure the angle is correct before making the final cut. Then I cut the bow. Again, be sure to use a multi-toothed carbide blade and do not rush the cut.

Next, lay out the guidelines for inletting the end grain of both limbs. Just hold the joint half in its respective limb (male in upper and female in lower) and trace around the outer perimeter.                    

Remember the end grain inletting is done at an angle (about 9.5 degrees) to the mating surfaces of the joint. This is to facilitate the narrow end of the male dovetail entering the wide opening of the female from the belly of the bow. It also creates a third tapered surface which acts as a final stop when the limbs are driven together. It may sound complicated, but it is not very difficult to get right.   First, using a carpenters square scribe a line over to the end grain of the plywood.

The  mycarta spacers supplied with the joint seal the end grain of the limbs and replace the material removed with the saw blade. There are several of different thickness. Pick two which most closely match the blade thickness. Using the lines just transferred to the plywood, position the female dovetail on the side of the jig so that the mycarta spacer aligns diagonally across its side as shown.

 The mating mycarta surfaces run from the upper edge of the female at the back of the bow to the bottom of the opening of the female at the belly of the bow. If the angle of your cut was a little off the mark, this is the best time to correct for it. To do so is quite simple. With the mycarta still in place,  position the female part of the joint against the side of the jig in line with the mark you transferred to the end grain of the plywood and scribe a line along the bottom edge. Then assemble the joint and position it against both halves of the jig as shown. Note that both mycarta spacers have been pinched between the halves. The two spacers you use should be those which most closely replace the material removed by the saw blade.

The arrows in the above photos point to the ends of the lines drawn across the plywood ends to mark the belly side edge of the joint inlet. The lines drawn along the joint edges re-establishes the depth and angle of the bow end grain inletting. Next, place the jig halves back to back and align the newly traced lines with each other along the edge of a piece of board as shown and fasten them together with drywall screws. Be certain not to place a screw directly over either limb!!    

One of the interesting things about this installation is the fact that the inletting angle in one limb is the mirror image of the other. They are both the same number of degrees from the centerline of the cut surface. With both sections secured to each other, mount the jig to the edge or bottom of the work bench as shown.

The color image shows the router bit (yellow) set to the top edge of the board used to tie the limb jigs together as seen from the bottom of the bench. Note the line drawn on the plywood to the right. Set the depth stop on the router at this position because that is the finished inletting depth for both the female and male dovetail.

The last of the inletting can be done as in the diagram for doing just the riser block or you can make a simple tool to guide the router inside your outline in the end grain of each limb. It is nothing more than a piece of thin stock with a rectangular hole cut in it which is 7/8" longer and 1/2" wider than the base on the router. That will allow enough travel for a 3/8" router bit to cut the right size opening for the dovetail to fit snugly. Center the jig over each limb and gradually lower the router bit until the preset stop is reached. Keep checking to be sure you are within your joint outline and that you have not gone beyond the proper depth. Use the appropriate joint half to check the fit as you go. You may find a minor adjustment is needed to align the dovetail portion of the joint with the tang inletting you did earlier. 

Once you are satisfied with the inletting fit the bow is ready to go back together. Separate the jig halves from the bottom of the bench and away from the board and place them on against the rail as shown.

The intent here is to place the bow along the rail in exactly the same position it was before it was cut but, now with the joint inlet into it. Note the mycarta spacers are once again pinched between the jig halves. With all pre-cut alignment marks re-established, there should still be a tiny bit of wiggle room around the joint in both limbs. This allows the MT-13 bedding epoxy to conform to any imperfections in the job while keeping all the alignment marks on location.

Once satisfied with the dry fit of all the components, prepare a small quantity of the MT-13 and reassemble everything just as before and clamp to the rail using only moderate pressure. Be especially careful not to apply too much downward pressure on the tang because it is easy to compress the foam on the belly side of the bow.

Now allow the project to set overnight while the epoxy cures. Be sure not to try installing any screws before the epoxy has cured!! If you do the limbs will surely be pushed out of line. The next day clean the epoxy out of the six holes along the tang with a countersink. This will re-center the pilot holes. Drill and tap for whichever screws you intend to use. The machine screws usually work better in a retrofit because there is often hard material like fiberglass to get through and a machine tap will handle that much better than the wood screw. Mix another small amount of epoxy and apply it to the screw threads and tighten them in place. Apply a bit more epoxy over the entire tang area and clamp whatever material you intend to use to fill the void down the back of the riser. In this example we used a piece of oak which closely matched the original overlay.

After the epoxy has once again cured, use the slot between the jig halves as a guide and cut the filler piece through to the face of the dovetail. Remove all clamps and separate the limbs by putting a block under the belly side of the lower limb (female) and striking the back of the upper limb (male) sharply with a mallet. It is the same procedure as shown in the instruction tutorial to separate the riser block alone. Clean the excess epoxy from the end grain holes with the hand drill and countersink and drill, tap and install the screws just as before along the tang. Carefully dress off the ends of the material used to cover the tang even with the cut surface and get ready to install the mycarta spacers.

Be very sure the metal surfaces are cleaned of any excess epoxy and that there is nothing keeping the tapered dovetail from mating completely. An easy method to check this is to assemble the bow without the spacers and bump the side of it with the heel of your fist. If any vibration can be felt or heard, the joint still has interference in it somewhere. Do not install the mycarta until the bow passes this test. 

The straight walled punch used on the mycarta has the same outside dimensions as the joint. That means you will need to chamfer the hole in each spacer so it will fit around the dovetail at the cut angle. Go a little long to allow some extra room back to belly when the bow is assembled. This is important because if there is not enough end clearance the joint will stop short of the full metal to metal contact needed to keep the limbs together. Do all fitting dry and again check for vibration. When satisfied with the fit, apply a thin coat of lithium grease or other release agent to the mating mycarta surfaces. Next, apply Smooth-on epoxy to the end grain of both limbs around the joint. Be conservative with the epoxy when applying it to the end grain because if you overdo it, some will get around the inside edges of the spacers and make the limbs much more difficult to break apart once it has set. With the spacers in place slide the limbs together and, using a rubber mallet, drive the joint tightly home. Because the joint is a tapered dovetail, it pulls the limbs closer to each other and clamps the spacers securely against their respective limbs. Clamp the spacers together and allow the epoxy to cure. Remove the clamps from the spacers and trim them down close to the riser, but do not completely reshape the riser until you once again separate the limbs by supporting the belly of the lower limb and striking the back of the upper.  After you have taken the bow apart, clean any excess epoxy from in and around the dovetail, slide the limbs tightly together and refinish the riser. Congratulations!! You have successfully converted the old one piece bow into a take-down!!

So far I have converted four bows, three longbows and one recurve using this method. All have retained their original dimensions and shooting characteristics. I left the grip area of the recurve and one longbow unwrapped. On one of the other longbows I wrapped leather and the second I covered with a rubber sleeve. 

Send mail to JStepp@sppets.com with questions or comments about this web site.