Another longbow build

rikyrik81

New member
Hi again.

Im going to start my second longbow soon, im going to do a triple laminate this time.

I have 2 questions,

1. for a combination would ash/oak back with a tropical hardwood core and maple belly be a good choice?

2. My last bow bent unbraced in the direction it would if braced, is that called string pull? How do i avoid that?

Thanks


Sent from my iPad using Tapatalk
 
D

Deleted member 7654

Guest
A bow that is permanently bent towards the belly is said to have set. After a day shooting the bend will be even more, but it will recover overnight, the bit of bend that recovers is called string follow.
Most bows take on a litte set during tillering, this can be minimised by gluing up laminates with a little bend in the opposite direction.
Bowyer's Diary: Glue Up
you need to be philosophical about a little set, it shows the wood is working ahrd and it is less bad than a bow breaking or chrysalling* on the belly.
The choice of woods in a laminate can make a big difference too. I can't offer much advice on that tho, as it's not my thing.
I measure set by putting a bow flat on the floor surface belly down. If the tips touch the floor that's ok, if you can get 1 finger under the grip, still ok. 2 fingers is just about ok. 3 fingers is pretty bad. Of course this doesn't apply to deflex reflex designs.
Del
* A chrysal is a fine compression crack on the belly, generally occurring a a group of two or three and often running diagonally.
 

rikyrik81

New member
Thanks thats very helpful.

I changed my mind slightly, ive done 4th laminate using a bamboo strip.
So it is oak 3mm then bamboo 3mm then 6mm tropical hardwood tapered at both ends to form the core then maple belly over thickness, the theory being that bamboo makes a great backing but i dont like the look of it and varnish takes alot longer to dry on it so i will use a sanding machine to bring the oak down to about 0.2 of a mm or whatever which will move the bamboo up to make the backing but leaving a very thin veneer of oak hiding the bamboo, thats makes it 3 laminates and a vaneer.

Its drying in a reflexed form so hopefully i can avoid a set and also ill try not to over stress on the tiller which im pretty sure i did wrong on my last one.

A slight change of subject but can glass/carbon laminate be glued on with contact adhesive? If anybody knows it would be handy to know for future projects, i know epoxy is used commonly but im wondering if its because its just easier to use, contact is used for gluing laminate material to wood so i cant really see why not but interesting to know for sure.

Thanks


Sent from my iPad using Tapatalk
 
D

Deleted member 7654

Guest
Contact adhesive won't be good enough and glass/carbon fibre (spits on floor) will prob be too strong for the timber belly.
You'd need a good quality epoxy.
A back has to stretch in balance with the belly compressing, glass and carbon fibre are too strong. In fact most woods are better in tension than compreesion anyway.
If you want to use glass/carbon, put it on both back and belly.
Keep it simple is still best advice.
Del
 

rikyrik81

New member
Ok thanks, that answers my question perfectly.

Yeah I agree with you, I would only use it on both sides of a flat type bow. I might start making recurve and reflex deflex bows etc

Thanks again





Sent from my Moto G (4) using Tapatalk
 

WillS

New member
You've put your laminations together in the wrong order ;)

Maple is fairly poor belly wood, oak is terrible back wood. With the woods you've got, you would have a much better result using bamboo as the back wood, your tropical hardwood as the core and oak as the belly. Oak isn't great belly wood either but it's the best out of what you've mentioned.

The ideal bow made from your woods would be bamboo or maple backing over the exotic hardwood belly, with nothing else.
 

rikyrik81

New member
I think I mentioned that I'm not using oak as a backing it's a veneer over the bamboo which is the backing
and tropical hardwood is the core :).

I wasn't sure about the Maple but have been previously advised that I should use maple with a backing so thought it might be ok,

Thanks for the advice I will most probably try that for my next build.

Sent from my Moto G (4) using Tapatalk
 

WillS

New member
I think I mentioned that I'm not using oak as a backing it's a veneer over the bamboo which is the backing
and tropical hardwood is the core :).

I wasn't sure about the Maple but have been previously advised that I should use maple with a backing so thought it might be ok,

Thanks for the advice I will most probably try that for my next build.

Sent from my Moto G (4) using Tapatalk
If it's a veneer OVER the backing, then it's the backing...

The back of a bow is the final and outermost part of the bow, and is doing all the tension work. If you glue a thin veneer of oak over the bamboo, then the oak is taking the tension. Oak is poor in tension, so will likely splinter (especially if it's so thin as to be considered a "veneer"!) and the sudden failure of the tension wood will almost certainly cause the bow to fail.

Just get of the oak. Bamboo is a perfect backing wood, and doesn't need anything glued on top of it.
 

rikyrik81

New member
Understood, I didn't realise a thin veneer would have such an effect,

Thanks

Sent from my Moto G (4) using Tapatalk
 
Top