Recurve Build #3, 64" I-beam (tutorial)

This bow came from an idea I had based on my limited experience shooting recurves.  I had been wondering why I don't see many long 1-piece recurves commercially available anymore. Bear used to make lots of lengths, but now it seems that 60" is the longest bow that I commonly see at the sporting goods stores or in catalogs, unless you go to a longbow design. Maybe it's because the longer bows were for the target shooters and that market went to take-downs. I'm not sure, but I still like them. The longest Bingham's Project, Inc. plans is also 60". These are great shooting bows, but I am tall and have a long draw and I really like the pull of the longer bows that I have tried. In fact, I have been shooting a 66"/44# Bearcat in a traditional 3D league and it is working really well for me. So, I was thinking about what it would take to alter the plans to make a longer bow, like maybe a 64" version. What I was contemplating was how to scale the design. 

I have a few bows that I measured to see how they are laid out. I measured the limb from tips to fadeout along the belly. I measured the riser from fade to fade in a straight line along the side of the riser. I know these are not exact measurements as it's hard to see where the fade ends and not all string grooves are in the same location, but its close enough. I wish I had a bigger sample size.

It appears that the Tigercat adds one inch to each limb to get its 62" size, but the other bows seem to have added length mostly to the riser, creating room for a longer sight window and more mass. I was surprised how short the limbs were on the Tamerlane. It is such a smooth bow to draw and a pleasure to shoot. I wish they had made one at 50# or so.

Since I will have to spend time and $$ to build a new press to test this out, I wanted to decide which way to go. I could just find a source for a 4" longer riser (or build one), leaving the limb design alone, or I could try to put 2" more into the riser and 1" into each limb. After talking with the good members of the TradGang forum, I started to lean toward the idea that the riser was the place to make the length increase, while using the 60" limb design without change.  The longer riser will change the geometry of the pull to produce that "longer bow" feel that I like.

I found out that Bingham's had once developed and sold a 68" "Target Bow" recurve plan.  I even got a copy of this plan from one TradGang member so that I could research the design.  I really enjoyed seeing these old plans and comparing them to their current 60" plans.

(click any picture for full-size image)

I took some shots of the 60" patterns laying next to the 68" drawings. I noticed that the lower half of the riser template for the 60" bow has changed a bit. It looks like they moved the grip angle down a bit more in the current version (slants toward the lower limb more quickly), maybe to make it more comfortable.

The 68" pattern is basically the 60" limb design with a longer riser (30"). However, as you can see in the lower photo, the angle of the fades is different as well. It is closer to angle of the Tamerlane and other target bows I have seen. Also, there is a wider sight window and rest/shelf. Those types of details are personal preferences and are easily changed to have more/less wood in the riser. Overall, I think this info makes putting a 64-66" design together a lot easier. 

After getting a lot of info on 64"- 69" recurve designs, I began making a plan to build one. I decided to start with a 64" bow. I made a plan for a press by modifying the Bingham 60" plan to handle a longer riser and adding some minor changes from some other designs. It's not too difficult, but does require all the work that goes into building a new press.

I also decided to build my own hardware for this press. The Bingham product costs about $25/set (plus S/H & taxes) and 2 sets are required. It cost me about $30 to make these with stuff from the local hardware store. After the cutting, drilling, heating, bending, welding, and grinding, there will be an hour or two invested in production, so you will have to decide if it's worth it or not.

Because I will have to make my own riser block for a longer bow, I decided to use what I could find locally for my first bow. I think it will be expensive to buy a 2x3x26" block of exotic wood. Plus, I have had a hard time finding a block that size. It seems that thinner wood is easier to find.

At a local place, I got a nice piece of walnut with some figure in it. I think its beautiful.

I had a piece of maple that I decided to sandwich in the middle.

I glued up the block with smooth-on, then trued it up and cut the initial shape.

Then I added a couple strips of black phenolic with a thin piece of bocote in the middle.

This is the riser shape I am thinking about doing.

I decided to go with black glass on the back and clear glass on the belly, with birdseye maple visible. All the rest of the core lams are hard maple.

I finally got it in the press and into the oven.

I put my "beater" blade on the bandsaw to cut the limbs and got them roughed out. Bingham's says that a 4 TPI, skip toothed, neutral rake blade will last the longest, even though it will smoke and squeal a bit. So I keep one blade just for this chore, which keeps my other blades sharper for wood. The template I used is the same as for the 60" pattern recurve limbs. Then I use the drum sander to finish the shaping, just like the other builds.

I also got the front profile and grip area roughed out.

After smoothing out the front profile with a sanding drum, I glued on some maple and walnut detail strips. This is where I learned just how thin wood needs to be to bend correctly. The phenolic strips, though thicker, bend easily compared to this wood. But I wanted to try using wood accents this time, so I messed around until I got it right.

Next, I took a piece that was cut from the front profile and glued it on to help build up the heel of the grip. 

After some cleanup:

I also cut out the sight window and did a bit of shaping on the drum sander. I still needed to take more wood/weight off, but it's starting to feel comfortable when gripped. 

The front detail strips hide the maple line down the center, but they also blend nicely into the curves as I shape them. I think it makes it looks nicer.  The grip heel piece also works nicely to shape the handle and add detail.

After finish sanding with 100, 120, and 220 grit paper, I wiped it all down with mineral spirits and let it dry.  Then I started applying coats of Tru-Oil, sanding between each until a smooth surface was achieved. Then I began applying coats of Minwax Wipe-on Poly, which I feel leaves fewer lines and other problems in the finish.  These are some pictures in full sunlight, showing the details.

Here is the figured maple sight window and walnut side grain with black glass.

Walnut and maple front covers that hide the middle stripe.

The middle layer shows in the back and the birdseye maple limbs are beautiful.  This is my first time using clear glass and I like how well is shows the wood pattern, especially on a 2" wide limb.

The black-bocote-black sandwich and walnut grain shows well on the side.

This shows the grain on the grip area.

And here is one shot of it strung and one at full draw.

OK, so I feel like I need to put in a final results section along with my impressions of this bow.

Here are the stats for this bow:

- target stats: 64", 45# @ 28", 2" wide

- achieved stats: 65", 53# @ 28", (58# @30")  205fps with a 378gr arrow (at my 30" draw)

- .040"  ULS black glass for the back

- .043"  ULS clear glass for the belly

- .070"  hard maple parallel lam for back 

- .100"  birdseye maple tapered lams for belly (taper: .001/1") (visible thru glass)

- .253" stack height: 

- riser: 2 x 3 x 26", walnut with maple i-beam 

This bow is fun to shoot.  I like the feel and dimensions of this bow a lot more than the 58"-60" bows of the same style.  This one draws and shoots very smoothly and it sure puts some speed on a shaft.  I still need to take it to the range and chrono the speed, so I will add that data when I get it.  I can tell that it will be over 200 pfs for sure. The riser is quite dead in the hand and comfortable to shoot.  I'm sure the heavier riser has something to do with that.  I will try some anti-vibration measures on the limbs to see if it offers any improvements. 

This bow would be great for shooting longer distances and for hunting.  I think I need to try another one that hits closer to my target stats of 45# or less, so I think I will try .010" less stack height next time and see how it comes out.   One thing about this style of bow, compared to the r/d longbow that I built, is that it takes longer to shape the large riser section to remove weight and slim it down for fit. Still, it is a great design to shoot, especially now that I have a longer version that fits me better.  I also like the wider limbs when showing fancy wood.