HHB Double Void Experimental Bow (3/4 finished)

[avcase]

Phil,
Yes, that’s the article!  Wow, the internet never forgets. Haha!

Alan

[avcase]

@avcase,

how did your bow compare to my HHB double void bow from a design perspective? I have both sides to the void stay same width and I match the slope of the belly with the curvature of the crown on the back of the bow. I do flatten out the slopes as I get closer to the outer limb so I have a smooth transition to the flat portion.

Phil,
Your bow is like the Jenkins design in cross-section in the hollowed out area of the limb?  At first glance, I thought it was just a hollow space in the middle of the limb.  I guess it depends on how thick the limb is compared to width. It looks like it is thick enough that it won’t flatten out much as it is drawn. Thin and wide will tend to flatten itself more as it is bent and will also be less stable.

Alan

Alan

[Philipp A]

Hi Alan,

The cross section in the area with the voids have sloped sides towards the centre when viewed from the belly. The slopes match that of the crown of the stave on the back and the thickness does increase a bit towards the handle where the two sides come back together. It then transitions into a belly ridge on the handle. Towards the outer limb the slope flattens again to assure a smooth transition to the flat section of the outer limb. If you click on the google photo link at the beginning of my posting I have a whole bunch of pictures posted, with some of them closer up where you should clearly see the slope.  I have some pictures of the bow on there as well when it was at an earlier stage (pre tillering) where I have not yet incorporated the sloped sides.  Let me know if you want any more pics closer up when I am finished with the bow, I would be happy to post them.

Cheers,

Phil

[Badger]

   I can just see myself making a hundred of these things trying to get them to break over right. I am glad someone else is working on this one.

[avcase]

   I can just see myself making a hundred of these things trying to get them to break over right. I am glad someone else is working on this one.

I agree!  It takes a lot of work to take a concept to a real working design. I used to spend a lot of time on different kinds of ideas. It can be a lot of fun, but it can be really time consuming and frustrating to get just right.  Regardless, I do think it is healthy to try stepping out beyond the tried and true sometimes.

Alan

[Jan de Bogenman]

for those who like to see, in the attachment is the same article, but with picture.  Dont remember the origin.

Would be great to see the results Alan.
Could be worth trying to cut some slots in an old bow.
Jan

[Philipp A]

Hi Jan,

I have clicked on your pdf file link but it contained zero bytes. Can you repost it?

[Jan de Bogenman]

Hello Phill, seems to be a problem to post it from my present location!!! But you can find the file in my first post.

[Philipp A]

Hi All,

I finally started shooting in the bow today and I am posting a couple of pics (they are not the best but it was minus 22 degrees Celsius when my son took them). I am now about 90% finished and I will continue to take some additional draw weight off the bow so I can fully draw it. It is currently 50# at 22". I think it will want to end up around 65# final draw weight @ 26". I have a maximum draw length of 26". I am concerned that the bow will get too thin if I try for less than that.

The bow actually shoots very nice and straight and has no hand shock. The bow weighs 606 grams / 21.4 oz and is almost exactly the same weight as the belly ridge bow I have made earlier this year which was also 67" n/n. I am using the same string for the bow. I forgot in my original post to add that I have been using two different scrapers in addition to the tools I listed to make the bow.

I have also added a pic that shows the slope of the side limbs in the section with the V slot. I did not experience any let off when drawing back the bow except that it didn't seem to stack quite as much as some of my other bows. I am still careful trying to find the limits of the bow since I have to get used to the way it draws. The pictures have also been added to the original google photo link if you want to view them in high res.

Happy New Year,

Phil

[willie]

Very nice execution and observations. Just now looking back at the "Haida Gwaii style bow" thread also, and I am reminded to not be so quick to dismiss some of the features seen on primitive bows that are not readily understandable.
The nuances that make one bow more usable or "sweeter" to shoot than another, can be somewhat subjective to the archer, and what we learn can just as well come from impressions that are difficult to prove in a scientific way. I hope you can share more opinions about what you are experiencing with your different limb designs.

[Philipp A]

Thanks Willie for your words of encouragement, it makes the tinkering worthwhile .

Happy New Year to you,

Phil

[hoosierf]

Neat bow, interesting about the hand shock. Cool idea and well executed.

[Badger]

   The bow is looking nice so far, has it started to take set yet?

[Philipp A]

Thanks @hoosierf, it is much appreciated!

@Badger: Yes the bow has taken so far net set of ~1/2". The stave itself had on the upper limb natural curvature about 6" from the tip and a hump as a result of a knot resulting in approximately 1/2" of curvature on the belly side. This lower limb had some natural reflex near the handle and some curvature belly side also ~ 6" from the tip. I believe I will end up with ~3/4" - 1" of net set once finished which is approximately where I am on my other HHB bows. So in short the double void design had no effect on set. I was careful to long string tiller it, but once the bow has been strung for a while and I had ~50 arrows fired it started to take a bit of set.

Maybe it has more to do in how I make my bows and maybe if I would aim for a lower draw weight (and not exceed that while tillering) before I start stringing them and shooting test arrows, I might be able to further cut down on set. I usually draw them to ~60# while tillering the bow since my HHB staves somehow want to end up between 60 - 70# @26". I have made one at 37# for my son's girl friend but found that the bows get awfully thin at those weights no matter how much I narrow the tips and I wanted to keep them somewhat robust so they can take a bit of abuse if that makes sense to you. But after reading about some of the speeds some of the people posting on here get with light draw weight bows I might need to reconsider my approach.

Any thoughts from you on this would be welcome!

Happy New Year,

Phil

[Jim Davis]

Just keep in mind that a thinner limb will bend to a tighter radius before taking set than a thicker one will. If you thin the limbs to reduce weight, you will not lose "robustness." If the limbs are already a good thickness (in your experience with HHB) then yes, it would be better to narrow them because you will get rid of more mass than by thinning.

I think you have a very visually appealing bow there. But I am sure the  design adds nothing to performance. The extra edges of each limb at the void are extra places for the Poisson effect to step in. I know you left the limbs wider at the voids to make up for the missing wood, but there is no net gain of available energy storage area, so it will behave like any other bow with the same amount of wood in the same regions of the limbs.