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Fibreglass laminated longbow - how to build

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jcs0001:
Some time ago I mentioned making archery bows.  There was some interest by forum members so here is some of the detail involved in building a glass laminated longbow.

I will be talking about “we”.  I have made quite a few dozen glass laminate bows over the last 15 or more years.  This has been a hobby although I have sold a few here and there.  A friend has become involved in the last couple of years and has done more of the final carving and finishing than I have.  Thus the two of us are involved in this project.

First a bit of terminology.  The “handle” area is called the riser of a bow.  The thin tips of the riser (top and bottom) are called the fadeouts.  The side nearest the archer is the belly of the bow and the other side the back.



A 66 in. bow made some time ago with the same mold we will be using.  It is resting on it's belly unstrung.



A closer look at the riser area.  The riser is Kingwood with some decorative veneer in the middle and the overlays are Kingwood Yew and Ebony.



Belly side of the riser.

I will be using inches because all of the components are available in that format. 

This type of bow is made up of fibreglass laminations on the outside with several layers of wood in the middle.  The bow we will make will have 4 thin wood laminations in the core.  One or two pairs of these laminations will be tapered (0.002 in. per foot), the remaining two are parallels.  The wood pieces usually range between 0.040 and 0.110 in thickness as they need to be bent over a form.  Most of the bows made on this form are composed of 4 wood laminations but I have used 5 in some bows.

The glue used to join the laminations and fibreglass together is epoxy, several types are suitable but I have used Smooth On for quite some time and like it's properties.

We will aim for a bow of about 60 lb. pull at a 28 in. draw.  All other things being equal the weight depends upon the shape of the bow, it's length and limb width, the thickness of the wood laminations and thickness of the fibreglass.  To some extent the thickness of the glue lines will effect the weight however we will be keeping them as consistent as possible – you will see this further on.

Our longbow has a complex shape – it isn't straight – in order to improve performance.  The shape will give it good arrow speed along with little hand shock.  I have used bows in the past that had so much hand shock that I had to check my teeth for missing fillings after a few arrows. :bugeye:  Such bows are unpleasant to shoot and can easily lead to wrist and forearm problems. 



The above photo shows the mold we will use along with two shaped risers.  The top surface of the mold in the foreground will become the back of the bow and the bow will end up with that shape when finished.  The top part of the mold along with heat strips is in the background.

In general we want a bow that has decent arrow speed and is consistent.  All things being equal a longer longbow is more consistent so we will be building a 66 in. bow.  If the finished bow weight is low we can cut it down to 64 in., increasing the weight.  Any shorter than 64 in. with this particular design and it doesn't work out well.

I will write this thread as a series of entries and may take a few weeks before being finished.

John.

Jonny:
Great stuff never delved in to bows but intrigued by the layered laminate glueing and setting and retaining the bend.
Been meaning for 16 years to make up a block form of laminated blank but never got round to it.


Have been shown a few times on stocks and how to set them over etc, quite frankly it scares me to death on several thousand £ of stock.

Tried Elm, quite springy and very strong.
So is the birch ply from Rutland Ply but also very stable.
http://pic20.picturetrail.com/VOL15/728921/1243583/228059233.jpg
http://pic20.picturetrail.com/VOL15/728921/1243583/311528971.jpg

Ever thought about pulling the bow up like how V springs should be made?

Gerhard Olivier:
Archery and Bow hunting is one of my many hobbies

Will be following this with lots of interest.


Gerhard

DavidA:
jcs001,

Hate to be picky,  but that isn't a longbow.  It's a recurve bow.

Dave.

jcs0001:
The last photo is missing from my first post so here it is:



Bottom of bow mold in the foreground (along with two riser blanks).  The top of the bow mold is in the background along with the two heat strips.

The bow mold is 2 in. wide and made from high density particle board (rangerboard may be another name).

John.

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