Bamboo-Cumaru-(ex-Ipe)-Massaranduba Bow Build-a-long

[Lehtis]

Hei, fellow bowyers!

I´ve recently started this experimental project and my aim is to make an ELB-stylish bow from bamboo, cumaru and ipe. Experimental because of cumaru seems to be rather explosive under pressure but seems to stand well under massaranduba in my earlier bows. Now I´m testing how ipe can handle this task. We´ll see later either a ca. 80 lbs @ 28" bow or fire wood.

So, ca. 5 mm bamboo is on back, belly ca. 8 mm ipe and tapered cumaru as core, ca. 1 cm at handle and 3 mm at limb tips. A slice of scrap massaranduba at handle area to give enough thickness. The slices were glued with Unibond-800, squeezed with rubber band and the limbs were forced ca. 7,5 cm (3") reflex at tips and 3,5 cm at 25 cm from the tips.

In the last picture you´ll see the bow on my tillering system, corners and belly rounded but not drawn with tillering string yet. More to come, stay tuned...

[Aaron H]

Your bamboo seems awfully thick.  I have heard,  and from my little experience,  that the thinner the bamboo, the better.  I like to thin my bamboo to about 1/16" on the sides,  which usually equates to about 1/8" or less at the crown.   Someone else with a little more experience may be able to tell you better though.

[Lehtis]

Aaron; I´ve heard that also earlier... but few other bows I´ve made have been working fine with that thick bamboo. Latest two 80 lbs and above. Perhaps I´ve got to make bamboo a bit thinner next time.

[Lehtis]

Some additional thoughts about bamboo thickness on bow´s back: I think (and may be wrong...) it´s also related to the thickness of the whole limb also. ELB stylish rounded belly should allow thicker bamboo backing than flat bows. In my bows 4-5 mm bamboo is  ca. 1/4 from the mid limb total thickness. Also, more bamboo at limb tips should give more speed because of it´s lighter than heavier core and belly woods.

[Lehtis]

No firewood (yet) but no bow either (yet)... I did preliminary tillering with long string and when I was changing to short string to finalize tillering I heard unpleasant noise. I found some longitudinal marks on the upper limb between the handle and mid limb showing ipe growth rings starting to separate. Either a hidden damage in the wood structure or ipe simply doesn´t stand the compression from cumaru and bamboo.

May the stave rest now for a while. Later during this winter I´m planning to sand all that ipe away and also thin a bit cumaru core and then glue my last massaranduba as new belly.

Until then: Season´s Greetings & Happy New Year 2016!

[Lehtis]

Couldn´t wait longer... Scratched ipe sanded away, cumaru core thinned a bit and massaranduba glued as new belly. Next tillering during coming silent evenings.

[Lehtis]

This stave still fights back. Now, when ipe has been replaced with massaranduba, the stave still doesn´t want to co-operate. The limbs are so narrow and reflexed that it turns upside down when stringing. Perhaps it´s not fully straight after all. Next step is to shorten it by 4-5" to 65-66" ntn, so it will still belong to longbow category. That will most likely happen a bit later because of I´m thinking to start another project first; Bamboo-Ipe-Osage Orange.

[bowandarrow473]

For the next project you speak of, why put such a heavy wood (ipe) as the core when you could reduce mass by using a lighter wood with better gluing properties ( maple maybe?). I'm not going to pretend to know squat about laminated bows but I have heard people experienced in making laminated bows say to others to steer away from heavy core woods. Just my thoughts though, good luck!


       

[Lehtis]

Thanks for your comments, bowandarrow473. The aim to use ipe as corewood is because of the one I have seems to be not so good quality to succeed as belly; tried. I also want some decorative effect from darker wood between bamboo and osage. Actually, I´ve already glued that combo, some 4 mm ipe as deco stripe. I´ll start another build-a-long later or publish this under bows category but here are a couple of pics.

[Lehtis]

While another project (that Bamboo-Ipe-Osage above, will be shown in it´s own chain later) presented unexpected problems requiring patching, I decided to continue with this one. I cut away 2,5" from both limbs and an narrowed the tips to ca. 12 mm (1/2") from the outward twisting sides. Now the stave is some 67" long and and obeys the string properly. It´s now roughly shaped and tillered close to the targeted weight waiting for horn nocks and fine tuning. Looks like this one is finally turning to functional bow.

[Lehtis]

This bow is now ready after all problems during making it. It ended up to rather aggressive little qutie but still fits in longbow categories if used in competitions. Domesticated water buffalo horn nocks and strike plate, handle from a leather bag found from flea market and 16 strands dacron string. Several layers of TruOil as coating. Other specifications can be seen in the pictures.

[Forest_Farmer]

Lehtis,  Thank you for including the build along pics, they are very helpful to those of us who are new to this.  Nice looking bow, well done!
Ed