Trilam LB

[pkearney]

Some close ups of the Bamboo Jarrah Merabau Long bow I am working on interestng the differences in the woods (grass)

[Stickbow Hunter]

Looks good and excellent glue lines.

Jeff

[Gringa Bows]

Looks good mate

[bigbob]

ditto the above.Like to see some more 'full frontal' shots

[hazard]

Great work mate

Show us a bit more, this looks like a project to sink your teeth into.

Hazard

[pkearney]

Shall do , I have cut the tapers and I am not sure what draw weight to aim at . with 2 laminations this design is about 45 lbs .

[Dennis La Varenne]

pkearney,

I would be interested in how much set your bow takes with the Merbau (Kwila) belly. It has only moderate mechanical properties and that is a very thick lamination of bamboo you have as a backing for an ELB. How long do you intend to build your bow?

[pkearney]

Hi Dennis the bow is 76 " and this a test run before I try some osage . The bamboo is 4 mm centre and tapers to 3mm at the ends

[Dennis La Varenne]

At that length, the Kwila is probably well within its compression tolerances.

[pkearney]

Removing the rind and ready to start tillering

[longbow steve]

Hi PKearney, Thanks for posting pics of your build. It is a bit risky sanding/violating the nodes on a bamboo backing but as your bow is quite long you may be safe. Cheers Steve

[Dennis La Varenne]

Removing the nodes will be interesting. I noticed that the bamboo backing was very thick, so it may not matter. All worth a try even if it goes against conventional wisdom.

[pkearney]

Thanks Steve I have tried not to remove all the node just smooth it out cheers Phill .

[longbow steve]

Cool, looking forward to the next installment

[perry]

As Dennis eluded too I would be concerned about the compression that such a thick piece of Bamboo will put on the Belly. With a Bamboo backing it is always a good idea to thin the Bamboo after profiling to as near too a Knife edge as possible, 3 mm at the crown at the Centre of the Bow to 1mm at the extremities is not too thin.

A question, Did this piece of Merbau have irridescent green Flecks visable as you Cut it. In my experience Merbau that is very Dark and has these Flecks makes pretty good longer Selfbows and nice heavy Arrows.

At that length and with a moderate draw I think it may be OK. Looking good to this point. Will watch and see how it shoots

regards Jacko

[pkearney]

bow (1 of 1)-2.jpg (55.66 KiB) Viewed 6401 times

Early days yet I have done some tillering and got a even tiller , fired some arrows at a low brace taken a 40mm string follow at rest .Bit more DW than I can handle so only 3/4 draw still looks good

[Dennis La Varenne]

The shape of your tiller at 3/4 draw is very nice indeed, but I am a bit concerned that it has taken 40mm of set already.

bow%20%281%20of%201%29-2.jpg (169.67 KiB) Viewed 6394 times

Because the tiller looks very even and the bends are very well distributed - as close to two beautifully circular arcs as possible (see pic), two things occur to me -

Firstly, the thick bamboo may already be forcing the belly to compress more than it ought to, and
Secondly, you may be bending it past its intended final draw weight which will overcompress the belly and force unnecessary set. If you want a 50lb bow for instance, (or whatever you want it to be), make sure you never bend it past 50lb until it reaches full draw on your tiller.

At 3/4 draw, don't bend it past 3/4 of its intended draw weight and so forth if that makes sense (the Jim Hamm principle of tillering).

You can check this approximately by weighting it at 3/4 draw and adding about 2 1/2 lbs for every inch past that up to your full draw. That total will give you a fair working approximate of what the bow will draw at full draw without actually drawing it out and overcompressing the belly. You then sink it as you tiller it until at 3/4 draw (or whatever stage you have reached) your bow is drawing 3/4 of your intended draw weight.

Your bow is so very well tillered already, I would only be sinking it (taking draw weight off) until it reaches full draw. Full draw length and full draw weight (plus a couple of pounds to allow for shoot sinking) should coincide.

[pkearney]

Thanks Dennis appreciate your help .I have over estimated the set it is really only about 28 mm at present and I think the 3/4 DW is around mid 30s ,need better scales ,so hopeful I can come at 50 @ 29" slowly slowly .

[Dennis La Varenne]

Even 28mm is a bit excessive at that stage of tillering on an ELB. However, if it stays under 40mm after shooting in, you will have a good shooter. Lovely tillering though.

[pkearney]

I think if I allow for natural curve that was in the bow to start the set is looking more like like 23 mm .we shall see .

[Stickbow Hunter]

Lookin' good mate!

Jeff

[ben8763]

Any updates on this one? Ive been checking back almost daily, have a surplus of Kwila so id love to see how this turns out

[pkearney]

I have finished the bow and fired few arrows DW has settled @50 # /29 " the set is more than I would like but 28 mm is ok .
Finished with bees wax I think this is certainly a usable combination .

[Stickbow Hunter]

Great to see you ended up with a shooter - congrats!

Jeff

[longbow steve]

Looks good, congratulations. Cheers Steve

[pkearney]

Thanks , the Merabau is fibrious and thats seems to mate well the jarrah which is a bit flakey and the bamboo holds it all together .
Very happy so far sends the arrows a good distance and has a nice twang on release .Have yet to find the right arrows but 30 " 40-45 5/16 sika went like a scared cat .

[pkearney]

Few more shots of bow still ok but set now 40mm so I feel Quilla is not 100% under compression .Top section shows bit of stiffness I think in last few centimetres . range 150 m easily .

[yeoman]

Top job!

Time to make another, methinks.

Dave

[Stickbow Hunter]

Loose good mate!!!

Jeff