Help with Sideways bending Limb

[Telrasha]

Hi all,

Currently working on building a new bow but need some help as the limbs are bending sideways when strung.

I am still very new so not sure if I made a stupid mistake somewhere but basically I am building a bow out of Manau Rattan stave (very soft and forgiving wood). I only recently picked up bow building again after 2 years and only made 2 bows back then. I wanted to try and make some different designs like recurve/horsebows with more fancy handles but also very limited in terms of space and tools I have currently.

I cut out the basic limb shapes and strung it on a long string and it looked fairly good, limbs were straight and fairly even.
I then cut out the handle (wanted a handle that was thinner than the limbs as I like how those bows look. This is where things went wrong. When I strung it again the limbs, especially the top one, is now bending sideways.

Initially I thought it was because the handle wasn't centered fully (one side was a bit more inset than the other) but tried rectifying that and doesn't seem to do much. Before I go further wanted to check in and see if any of you know why this is happening, how to rectify it (if at all possible) and potentially whether I can easily reinforce the handle to make it stiffer (somehow feel that is why it is bending now).

Below some pics of the bow to show the type of handle and the offset on the string.

[bradsmith2010]

the  handle is too thin,,

[2nocks]

I once copied an old bow in a museum with a similarly notched out handle.
it went out of 'true' and bent exactly as yours is doing.

the problem is the wood that's been removed from the handle grip area.
 
I tried steaming and clamping mine back in a straight line. then I tried steaming and clamping it past a straight line hoping in use it would find it's centre again. Then I gave up and called it part of the design 'flaw' or character of the bow. it shoots well and isn't immediately obvious.

I'd venture a guess that if you thinned the width of the bow's limbs to more closely match the notched out handle or feathered out the shoulders of your grip more gradually that the problem might be minimized. but this will also drastically change the power of bow. Have you shot it a lot and has the problem stabilized ? or does it continue to bend out of line ?

[Telrasha]

Thanks for the replies.

Now that I look at the wood and how it bends it does kinda make sense that the handle is the weak point and it is easier to bend sideways as opposide to straight as that is the thinnest part.

I haven't shot it yet as I was still tillering it and wanted to make it lighter.

The bow before this I gave a similar handle and recurved it. It shot pretty good at 30# before recurve and handle but then after recurving and putting in the handle it became very very light but there is no sideways bend so think you are right that when I carve down the limbs it will make it less pronounced maybe. I will give that a go and come back here with the results, worst case it can be a kids bow.

Another thing I was thinking about is whether putting some fiberglass on the handle would strengthen it enough to prevent the sideways bend but I have never worked with fiberglass so not sure how easy it would be to acquire and apply it would be. Any ideas?

Cheers,
Jelle

[bradsmith2010]

no fiberglass ,, 
you could make the handle stronger by glueing some more wood overlays underlays,, on it,,
or just cut that hande off and splice the limbs together,,
next time dont narrow the handle till the bow is tillered,,

[bownarra]

Just to clarify there is no problem having a handle narrower than your limbs are wide IF the handle gets apprioately thicker as the limbs fade into the handle.
The only way to sort this out is to shape some pieces of hardwood to 'fill in' the width you removed. Don't bother gluing them in place as it is highly unlikely any glue would hold. Maybe you could use one of the 5minute setting epoxies as they are super rubbery when cured, the bond strength of these sort of epoxies is generally pretty poor but...it will fill in any gaps etc. Use a strong cord to bind the pieces in place. Once they are bound in place then coat the cord with slightly watered down pva glue to set it in place.
This will stiffen the handle area enough that the bow won't want to bend sideways. It is a bit of a bodge but I know what it is like when you have put time and effort in!

[Telrasha]

next time dont narrow the handle till the bow is tillered

That explains why my previous one didn't bend sideways even with a narrow handle. I tried doing it before tillering this time to see if it would change the weight of the bow at all as the last one suddenly got very weak. Ah well guess this is all part of the learning process.

Just to clarify there is no problem having a handle narrower than your limbs are wide IF the handle gets apprioately thicker as the limbs fade into the handle.

So just to clarify narrow limb just make sure to do it after the tillering and have a much smoother transition from handle to limbs.

Thanks for all the help on this.

[Tommy D]

So just to clarify narrow limb just make sure to do it after the tillering and have a much smoother transition from handle to limbs.

Thanks for all the help on this.

Yes and remember there is a limit to how narrow a handle you can get away with - so leave them a bit thicker/ wider next time

[Telrasha]

Great thanks all!