Bamboo-maple-horn, 98#@28"

[Tuomo]

Hey tuomo, I really love this bow, can you tell me what formula you used to for the bamboo, wood core and horn for this build?
I use to build glass bows, and used a certain thickness for the glass, and a tapered core, and I would like to build one like this.

Thanks! There is no special formula. I made a mild deflex-reflex form, modelled with a VirtualBow -program. Then tapered the bamboo just by feeling, core with a tapering jig (0,004) and belly with another tapering jig (0,002). So nothing special. I have made a lot of bamboo backed laminated bows and this was "easy" to make. One reason was that horn belly is very reliable (or I hope so...), because it tolerates a lot of compression. Osage would has been an other option but it would has taken a lot more set. I have also ipe but its elastic modulus is so high that it is hard for bamboo backing. I will make one or two 45–50# similar bows for everyday use. I belive that the bow might be quite good in long term use.

I have a chrono but I don't have yet stiff enough test arrows for this bow, I have to make some. And then I have to tune my shooting machine for testing. Hopefully I will get soon some chrono readings, this seems to be a fast bow!

[simk]

Great Job Tuomo!
I sold a bunch of these in different designs over the last 3 years and they do all fine. It's a great combo - and as you mentioned, wood is a bitch compared to horn and makes bowyers life pretty easy. It's more elastic than any wood and takes away stress from the back.
However, that drawweight....(-; not bad. I have identified the bamboo as the weakest part.... had it failing a few times and decided not to make them more than 50#. So I'm a little impressed now (-;
However I see, you went pretty conservative, not putting net-reflex into. I work with 6-8" glued in reflex which seems to bring a lot of bending stress into the bamboo...
Congrats! Nice to see the concept spreading.

[Tuomo]

Nice bow! And nice to see that someone else has been making similar bows. Do you have link here in the forum to that bow, to see length, width, etc. specifications?

"I work with 6-8" glued in reflex which seems to bring a lot of bending stress into the bamboo..." – That is the reason I used very mild reflex. And playing with VirtualBow -program, it seems that too much reflex is just too much stress for the extra fps. More reflexed bow is a bit faster but usually too overstressed. In long term, gentle deflex-reflex form us usually the best.

Did you use moso-bamboo? I think that madake would be better option; at least japanese traditional yumi-makers consider that moso is too brittle and madake is the best of bamboo backings. I have some madake, I have to use it for next bows.

Maybe I have had just luck with moso, and this bow has under 50 full draws. It tells yet nothing, after 1000 full draw you will see how the bow last. But this is "nice to have" -bow, to give someone to draw and surprise!

[simk]

I don't think I have posted about this specific bow here. It's 50#28" and measures somewhat 66"ntn I think and its around 36mm wide. I generally make these 64"-66" and around 33-36mm in width.
I do play with virtual bow from time to time and I'm always impressed of how exact it can mirror reality. It's an eye opener in many aspects. When it comes to reflex you are probably right about heavy bows. With light bows reflex helps a lot with performance imho. Best think about is the higher initial string tension and the resulting smooth drawcurve. I just love that. With heavy bows I wouldn't recommend either - these also don't need that little + in energy storage.
I have also heard that Madake was superior to Moso. But when I buy my bamboo from the big bamboo trader he sells me "Moso (Madake)" hahaha....still confused....