Red Oak paddle bow

[Woodbear]

This is a paddle bow I made recently from red oak (board). The pic of it on the tiller stick was posted on Badger’s build along by mass thread for evaluation of the amount of handle to allow for in the formula. However there was some interest in the bow, so I thought I would post more pics in it’s own thread.

The length is 58” ntn, 59.5” overall.
41.7# @ 25” (only drawn to 26” but designed to be 50# @ 28”)
Brace height 6” from the bow back.
170 grains of linen string, including 8” of serving in the center made of 12# clear nylon fishing line.

The back is flat, and the belly beveled and rounded. This was done for extra safety in spite of the fact that red oak tends to take set. Total set is a little under 1.5” just unbraced and about 1” rested, with which I am satisfied given the design. The design for this bow was to have uniform strain in the working arms outside of the central 12” grip area, and moderately stiff tips for the last 6 inches. The working arm strain was supposed to be 0.7%, with the grip strain reduced to 0.6%. When I see the pic on the tiller stick, I can see more curve in the upper arm (right in the tiller stick photo).  I am sure that the mid to outer upper arm strain is a little over 0.7%, and the lower arm is likely a little under, when pulled symmetrically on the tiller stick.

I also carved in “micro recurves” by applying ¾ inch thick oak overlay blocks on the tips. This is mostly for looks, but also insures that there are no sharp bends on the string as it leaves the nocks.

In spite of the asymmetry of the limb bend (or maybe because of it??) this is one of the nicest shooting bows I have made. At 35-45# spine, arrows fly straight. I don’t notice any hand shock, or stacking. Point of aim at 30yd, is only a couple of inches higher than with a modern material recurve of 40# @ 26”.



Here is a better picture of the details of the bow. The grip is temporary leather lacing wound around the handle. The large black dot on the side indicates the intended arrow pass, and the small dot on the belly indicates the geometric center of the bow.



Lastly a couple pictures of the bow in action. Top is my son shooting at close to full draw. The bottom is with the arrow ½ way thru the power stroke. The bright sun light and light color wood combined to give a great picture of the bow in motion. You can see the blur of the tips in motion, and how the blur lessens all the way down to the grip where the motion is so small the details are crisp. You can even see a faint ghost of the string motion. If only I knew the CCD integration time I could probably calculate the speed of the arrow & bow parts.




Dave

[medicinewheel]

that is a nice bow! maybe a bit too much bend in the outer right limb; but sounds like you intended that? i'd believe the mid/inner limb there wouldn't work enough!?
the micro recurves look awesome! would love to see that from front, too! bigger pic would be great
how wide is the bow at the widest part of the limb?
again: nice bow, frank

[Pappy]

Very nice bow,very nice job.
    Pappy

[DanaM]

It looks nice to me, the paddle bows are very appealing.
Ya lost me with all the math stuff

[Dustybaer]

i'm with you dana.  just love the silhouette of a paddle bow.  very nice bow, indeed.  i like those "mini-recurves" too.

[OldBow]

Very nice! Paddle Bow, eh? That might be a future project for me.  Nice tips, too. Got your bow bookmarked for Feb Self Bow of the Month.

[jamie]

cool tips. bow looks great

[michbowguy]

man , im goona have to start steppin' up my game. you guys are gettin realy good at bendin' wood!
great lookin' bow!

jamie

[Justin Snyder]

I like the smooth flowing lines and the recurves are cool.  Justin

[Woodbear]

Thanks for the interest in the bow. I love the paddle bow shape and am glad of the company.

Regarding the right (upper) limb, it was the result of rushing. I usually design the bow with the aid of a computer program I wrote to have uniform strain and a symmetric bend. Once I know the “theoretical correct” dimensions for the bow, I cut it out with the band saw at a little over the intended final thickness. Next I measure the actual thickness at some 20 stations on each arm, and file little grooves on the belly down the 5 thousandth of an inch over the final thickness. Then all I have to do is take the wood off down to just remove the grooves, with the spoke shave & scraper. The last step is to check the draw at the intended weight, exercise, check the bend, and make final adjustments.

This time I was in a hurry to have the bow ready for Christmas. I took the grooves right down to the final dimension, and forgot that I had 5 thousandths of masking tape on the back….. The net result was that I was about 10 thousandths under thickness on that bendy part of the upper arm. The bow was right on the intended weight and I had no wood available to adjust the tiller. So I decided that some “positive tiller” was OK, and it seems this was a good choice as the bow is a real sweet shooter.

Having calculated the strain in the wood, including the handle, I find it interesting that a lot of bowyers see the inner part of the bow as stiff. The bow is at 85% of maximum strain thru the handle, and actually storing quite a lot of energy if my calculations be correct. The handle is 1.2inch wide by ¾ thick. This flares out to 2.5 inch wide at the widest part of the limb, while decreasing to less than 3/8 thick. This combination of large increase of width with decreasing thickness seems to look stiff to the eye, but computes out to have significant strain from the subtle bending.  Perhaps I could make it bend more in the inner arms, but I am hesitant to let the computed strain be so high there just to satisfy the eye.

The rest of the arm tapers to 3/8 wide at the tips.

Again, thanks for the interest.

Dave

[Ryano]

Thats about the coolest looking board bow I've ever seen. Looks like a good design for red oak to.